Thursday, December 2, 2010

Takkan Ustazah tu, tak tahu?

Ramai Muslimah yang menutup aurat tetapi sebenarnya tidak menutup aurat. Perkara ini kelihatannya semakin berleluasa di kalangan para ustazah yang mempunyai pendidikan agama yang bukan setakat di sekolah rendah tetapi sudah sampai ke peringkat universiti. Malah sudah juga bergelar graduan pengajian Islam. Ia adalah sesuatu yang sememangnya tidak sedap di pandang mata. Ini kerana yang sudah tahu itu seolah-olah buat-buat tidak tahu. Malah tidak keterlaluan untuk dikatakan ia adalah satu fenomena yang amat mendukacitakan.

Apabila seorang yang tahu dan faham dengan apa yang dikehendaki oleh syariat meletakkan diri umpama orang awam bagaikan satu musibah dalam institusi pembelajaran agama. Agama dicemarkan dan dirosakkan dengan pencampuran antara yang bukan agama dengan yang agama menyebabkan masyarakat Islam keliru yang mana satu agama dan yang mana satu bukan agama. Akhirnya masyarakat Islam yang seringkali cenderung beramal dengan amalan seorang agamawan itu melihat yang bukan agama itulah agama. Akibatnya timbullah kata-kata seperti ini: 'Ustazah tu pun pakai macam ni? Kalau agama kata tak boleh dan salah, kenapa dia pakai. Takkan ustazah tu tak tahu..." Sedih, bukan? Ketahuilah, semua ini berlaku dek kejahilan dan ketidakmahuan mempraktikkan ajaran agama oleh orang agama itu sendiri. [Ini baru sahaja dalam bab penutupan aurat seorang Muslimah belum lagi dalam bab-bab lain dalam hal akidah dan ibadah].





Saya tidak berniat untuk menyindir sesiapa, malah bukan juga berniat untuk mengutuk 'usaha murni' muslimah-muslimah dalam mempelbagaikan pemakaian tudung dan memperkenalkan pakaian-pakaian yang kononnya adalah 'busana Muslimah'. Cumanya saya prihatin, mungkin dalam keghairahan untuk melakukan kebaikan kita terlupa dengan kehendak asal syariat itu sendiri.
Ada kata: "Keimanan aku bukan terletak pada labuhnya tudung aku".
Ya, benar..siapalah kita untuk menilai keimanan seseorang dari sudut pemakaiannya. Memang kita tidak layak. Tetapi menutup aurat dengan sempurna dan melabuhkan tudung itu adalah SATU KEWAJIPAN yang dituntut dalam agama tidak kira kamu itu baik atau tidak. Jika kita kata kita beriman, tentu sahaja kita bertindak sesuai dengan kehendak Allah dan Rasul-Nya,bukan?

Mungkin ada antara akhawat Muslimah saya yang bergelar ustazah terlupa, Allah s.w.t telah berfirman:




Maksudnya: "Wahai nabi, Katakanlah kepada isteri-isterimu, anak-anak perempuanmu dan isteri-isteri orang mukmin: Hendaklah mereka mengulurkan jilbabnya ke seluruh tubuh mereka yang demikian itu supaya mereka lebih mudah untuk dikenal, kerana itu mereka tidak di ganggu dan Allah adalah Maha Pengampun lagi Maha Penyayang" [al-Quran, al-Ahzab:59].

Nabi s.a.w pula bersabda yang mana maksudnya:
"Dua jenis ahli neraka: (1) Orang yang mempunyai cemeti seperti ekor lembu untuk memukul manusia (2) Wanita yang berpakaian seolah-olah tidak berpakaian. Mereka condong semasa berjalan dan mencondongkan orang yang melihat. Kepala mereka seperti bonggol unta. Mereka tidak akan masuk syurga dan mencium baunya....." [H.R Muslim].


Akhawat bergelar ustazah yang saya kasihi, belajar agama menuntut kita memahami dan mempraktikkannya lebih-lebih lagi bila mana ianya WAJIB. Dalam hal-hal yang JELAS DAN TERANG seperti ini, kita tidak boleh beramal mengikut 'rasa', adakah beriman dengan al-Quran dan hadis Nabi s.a.w yang sahih itu perlu separuh-separuh? Mana yang kita suka dan mengikut selera kita, kita laksanakan. Manakala mana yang kita tidak sukai dan tidak menepati citarasa kita [dan peredaran zaman], kita tinggalkan?

Dalam hal ini, saya tidak perlu berbual panjang lebar dan berjela-jela. Cukuplah penulisan ringkas ini sekadar mengetuk minda kita yang terlupa barangkali agar tersedar supaya perkara ini dilihat semula berdasarkan tuntutan syariat. Suka untuk saya katakana bahawa aurat perlu ditutup sebagaimana yang dikehendaki oleh Allah dan Rasul-Nya bukan sebagaimana yang dikehendaki oleh peredaran zaman dan trend yang melanda dunia fesyen. Moga perkara ini dapat kita muhasabahkan bukan sahaja untuk diri yang sedang membaca tetapi diri saya juga.
Wallahu'alam.

adapted from Sakinah Saptu

Wednesday, November 24, 2010

Insya Allah

Every time feel like you cannot go on
You feel so lost
That you're so alone
All you see is night
And darkness all around
You feel so helpless
You can’t see which way to go
Don’t despair and never loose hope
Cause Allah is always by your side

Insya Allah

Insya Allah
Insya Allah you’ll find your way


Insya Allah
Insya Allah
Insya Allah you’ll find your way


Every time you commit one more mistake

You feel you can’t repent
And that its way too late
You’re so confused, wrong decisions you have made
Haunt your mind and your heart is full of shame 


Don’t despair and never loose hope

Cause Allah is always by your side
Insya Allah

Insya Allah
Insya Allah you’ll find your way 


Insya Allah

Insya Allah
Insya Allah you’ll find your way

Turn to Allah

He’s never far away
Put your trust in Him
Raise your hands and pray


Ooo Ya Allah
Guide my steps don’t let me go astray
You’re the only one that showed me the way,
Showed me the way

Showed me the way
Showed me the way

Insya Allah

Insya Allah
Insya Allah we’ll find the way

Insya Allah
Insya Allah
Insya Allah we’ll find the way 

Insya Allah
Insya Allah
Insya Allah we’ll find the way

Insya Allah
Insya Allah
Insya Allah we’ll find the way

Insya Allah
Insya Allah
Insya Allah we’ll find the way

Tuesday, November 9, 2010

Adab Menziarah

Sentiasalah mengingati mati dan menziarahi kubur
Adab Menziarahi Kubur
  • Beri salam kepada semua ahli kubur
  • Baca al-Fatihah dan niatkan pahala bacaan kepada orang tertentu
  • Bersihkan persekitaran kubur
  • Ambil iktibar bahawa kematian datang bila-bila masa
  • Selalu ziarahi kubur orang-orang soleh

Adab Menziarahi Orang Sakit
  • Berziarah selang sehari jika mampu
  • Jangan berziarah terlalu lama kerana dikhuatiri mengganggunya
  • Melahirkan rasa kasihan dan simpati kepadanya
  • Jangan terlalu banyak bertanya tentang sakitnya
  • Mendoakan pesakit agar segera sembuh
  • Tidak melihat auratnya dan cuba elakkan
  • Membisikkan kalimah syahadah di telinga pesakit itu dan menghadapkannya ke arah kiblat.

Do Not Do After Eating

Don’t do these things after meal…
  1. Don’t smoke- Experiment from experts proves that smoking a cigarette after meals is comparable to smoking 10 cigarettes (chances of   cancer is higher).
  2. Don’t eat fruits immediately – Immediately eating fruits after meals will cause stomach to be bloated with air. Therefore take fruits 1-2 hours after meal or 1 hour before meal
  3. Don’t drink tea – Because tea leaves contain a high content of acid. This substance will cause the Protein content in the food we consume to be hardened thus difficult to digest
  4. Don’t loosen your belt – Loosening the belt after a meal will easily cause the intestine to be twisted & blocked.
  5. Don’t bathe – Bathing will cause the increase of blood flow to the hands, legs & body thus the amount of blood around the stomach will therefore decrease.   This will weaken the digestive system in our stomach
  6. Don’t walk about – People always say that after a meal walk a hundred steps and you will live till 99. In reality this is not true. Walking will cause the digestive system unable to absorb the nutrition from the food we intake
  7. Don’t sleep immediately – The food we intake will not be able to digest properly. Thus will lead to gastric & infection in our intestine
From: nazrichik.com

Monday, November 8, 2010

Malaysia to design own EV71 vaccine

September 16, 2010
 



KUALA LUMPUR, Sept 16 – A Malaysian biotech start-up is developing a vaccine to combat the Enterovirus 71 (EV71) virus which causes Hand, Foot and Mouth Disease (HFMD), a common illness which afflicts infants and children with fever, blister-like eruptions in the mouth, and skin rash.
The BioNexus-status company, Sentinext Therapeutic Sdn Bhd, said the development of the vaccine was important because children who contract HFMD from the EV71 virus face a higher risk of developing severe — and potentially fatal — neurological diseases.
Sentinext Theurapeutics was established by CEO Peter Wulff and chief scientific officer Jane Cardosa in 2009.
Wulff said the development of the new vaccine was an important step in the company’s effort to combat infectious illnesses.
Prof Mary Jane Cardosa

.
“Solutions for infectious diseases such as malaria, dengue and HFMD have been woefully inadequate despite the fact that these diseases affect billions of the world’s population — particularly the poor,” Wulf said in a press statement.
In July, Taiwan announced that it has started human clinical trials of its own HFMD vaccine, which should be ready for use by early 2011. Its first clinical trial is scheduled to be launched this month with 30 adults as trial subjects.
China also began its clinical trial earlier this year.
Sentinext, however, is adopting a different approach in developing its vaccines by constructing virus-like particles (VLPs), as opposed to conventional vaccines which use weakened or inactivated viruses.
Wulff said the “look-alike” particles mimic the shape of the real virus, triggering the production of the antibodies to fight the bug.
“Compared to older methods, this avoids introducing the real virus into the body which could cause side effects. However, it’s technically very challenging. Engineering the VLP requires not just good science but out-of-the-box conceptualisation as well as rigorous lab technique. It takes deep knowledge, creativity and thoroughness,” he added.
The Sentinext founder also confirmed that the company will proceed with its pre-clinical animal studies for its vaccine.
“The company has just completed the making of its first EV71 vaccine candidate and initial experiments have shown good immune response to the VLP. To prove safety and efficacy, the vaccine candidate must go to pre-clinical animal studies and, subsequently, human clinical trials,” he said.


This is good that we will developed our own vaccine against the virus.  Right now, researchers from USM (Prof Zainul Fadziruddin Zainuddin, Head Project) are doing the challenge study of EV71 in a mouse model. They are using the recombinant BCG and subunit vaccine which both expressing VP1 of EV71 in enhancing the immune response and antibodies production in mice in stead of VLP. The study is still in progress. From the preliminary results, it showed that immunized mice with both vaccines produced a significant of antibody.The projects were collaborated by the other institutions i.e UM (Prof Wong Kum Thong), UPM (Prof Khatijah Yusoff) and UNIMAS (Prof Mary Jane Cardosa).

Monday, November 1, 2010

Doa

Bacalah doa-doa ini semasa menghadapi sakit fizikal, mental dan iman.

كان رسول الله صلى الله عليه وسلم إذا اشتكى منا إنسان مسحه بيمينه ثم قال اِذْهَبِ البَأْسَ رَبَّ النَّاسِ وَاشْفِ أَنْتَ الشَّافِي لاَ شِفَاءً إِلَّا شِفَاؤُكَ شِفَاءً لَا يُغَادِرُ سَقَماً  ) رواه مسلم(  
Ertinya : Nabi s.a.w ketika didatangi aduan (sakit) oleh seseorang, nabi akan menyapunya dengan tangan kanan baginda sambil membaca " Jauhkanlah dia dari kesakitan, wahai Tuhan sekalian manusia, sembuhkanlah dia, dan engkaulah maha penyembuh yang tidak akan datang kesembuhan kecuali datang dariMu, kesembuhan dari jenis yang tidak akan kembali penyakitnya"( Riwayat Muslim)
 كان النبي صلى الله عليه وسلم يعوذ الحسن والحسين ويقول : إن أباكما كان يعوذ بها إسماعيل وإٍسحاق أَعُوذُ بِكَلِمَاتِ اللهِ التَّامَّةِ مِنْ كُلِّ شَيْطاَنٍ وَهَامَّةٍ وَمِنْ كُلِّ عَيْنٍ لَامَّة } . رواه البخاري(
Ertinya : Nabi s.a.w ketika sedang meminta perlindungan untuk Al-Hasan dan Al-Husain berkata : Sesungguhnya kedua-dua ibubapamu meminta perlindungan dengan (bacaan) yang dibuat oleh Nabi Ismail dan Ishak iaitu : "Aku berlindung dengan kalimah-kalimah Allah yang sempurna, daripada setiap Syaitan dan mahkluk berbisa dan dari setiap pandangan mata dengki & hasad yang berniat jahat" ( Riwayat Al-Bukhari)

 أن جبرائيل أتى النبي صلى الله عليه وسلم فقال يا محمد اشتكيت ؟ قال نعم , قال : بِسْمِ اللهِ أُرْقِيْكَ مِنْ كُلِّ شَيْئٍ يُؤْذِيْكَ مِنْ شَرِّ كُلِّ نَفْسٍ أَوْعَيْنٍ أَوْ حَاسِدٍ , اللهُ يُشْفِيْكَ بِسْمِ اللهِ أُرْقِيْكَ } . صحيح سنن " ابن ماجه)

Ertinya : Telah datang Jibrail kepada nabi sa.w dan berkata : Wahai Muhammad, adakah kamu mengadu kerana sakit? . Jawab Nabi " Ya". Jibrail membalas " Bacalah "Dengan nama Allah yang mengubatimu, dari segala perkara yang menyakitimu, dan juga dari kejahatan setiap jiwa,mata dan hasad. Allah akan menyembuhkanya dan dengan namaNya engkau disembuhkan" 


Baca tujuh kali dengan tangan diletak di tempat sakit , kemudian baca Bismillah tiga kali dan terus baca doa berwarna merah di bawah:  
أنه شكا إلى رسول الله صلى الله عليه وسلم وجعا يجده في جسده منذ أسلم فقال له رسول الله صلى الله عليه وسلم ضع يدك على الذي تألم من جسدك وقل باسم الله ثلاثا , وقل سبع مرات : أَعُوذُ بِاللهِ وَقُدْرَتِهِ مِنْ شَرِّ مَا أَجِدُ وَأُحَاذِرُ } . رواه مسلم
Ertinya : Seorang sahabat datang mengadu kepada Nabi berkenaan kesakaitan yang terdapat ditubuhnya sejak dari ia masuk Islam, lalu nabi mengajarkan berkata : " Letakkan tanganmu ditempat yang kamu merasai sakit itu dan bacalah Bismillah tiga kali dan kemudian bacalah tujuh kali : " Aku berlindung dengan kuasa Allah dari segala kejahatan  yang telah menimpaku dan yang aku ingin hindari
(Riwayat Muslim)

  قال رسول الله صلى الله عليه وسلم من عاد مريضا لم يحضر اجله فقال عنده سبع مرارٍ أَسْأَلُ اللهَ العَظِيْمَ رَبَّ العَرْشِ العَظِيْمِ أَنْ يُشْفِيَكَ إلا عافاه الله من ذلك المرض } . صحيح " سنن الترمذي "
Ertinya : Nabi telah berkata " Barangsiapa melawat orang yang sakit yang belum kelihatan akan tiba ajalnya (sakit yang dikira boleh sembuh), bacalah di sisinya tujuh kali : " Aku memohon kepada Allah yang maha agung, tuhan bagi arasy yang agung agar menyembuhkanmu". Tiadalah dibacakah itu kecuali akan disembuhkan dengan izin Allah dari sakit tersebut. ( At-Tirmidzi : hadis Sohih)



Adapted from original article from:

Zaharuddin Abd Rahman

Friday, October 1, 2010

Sifat orang lahir -Oktober

Sifat Bulan Lahir untuk bulan Oktober yang dikaji oleh Dato Dr Fadzilah Kamsah:

[][] Suka berbual. 


[][] Suka orang yang sayang padanya. 


[][] Suka ambil jln tengah. 


[][] Sangat menawan & sopan santun. 


[][] Kecantikan luar & dalam.


[][] Tidak pandai berbohong & berpura-pura. 


[][] Mudah rasa simpati, baik dan mementingkan kawan. 


[][] Sentiasa berkawan. 


[][] Hatinya mudah terusik tetapi merajuknya tak lama. 


[][] Cepat marah. 


[][] Macam pentingkan diri sendiri. 


[][] Tidak menolong orang kecuali diminta. 


[][] Suka melihat dari perspektifnya sendiri. 


[][] Tidak suka terima pandangan orang lain. 


[][] Emosi yang mudah terusik. 


[][] Suka berangan & pandai bercakap. 


[][] Emosi yang kelam kabut. 


[][] Daya firasat yang sangat kuat (terutamanya perempuan). 


[][] Suka melancong, bidang sastera & seni. 


[][] Pengasih, penyayang & lemah lembut. 


[][] Romantik dalam percintaan. 


[][] Mudah terusik hati & cemburu. 


[][] Ambil berat tentang orang lain. 


[][] Suka kegiatan luar. 


[][] orang yang adil. 


[][] Boros & mudah dipengaruhi persekitaran. 


[][] Mudah patah semangat. 

Saturday, August 28, 2010

kenapa ALLAH temukan kita dengan orang yang salah

Memang sakit bila cinta yg kita dambakan selama ini tak dihargai oleh insan yg bernama kekasih,apatah lagi kita dibuang begitu saja... tapi,itulah juga petanda terbaik untuk diri dan kehidupan kita pada masa akan datang.

1. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya apabila kita bertemu jodoh yg sebenar,masih ada rasa syukur kita pada ketentuanNYA.

2. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita dapat menjadi penilai yg baik.

3. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita sedar bahawa kita hanyalah makhluk yg sentiasa mengharapkan pertolongan ALLAH.

4. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita dapat KASIH SAYANG YANG TERBAIK,KHAS UNTUK DIRI KITA.

5. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita sedar bahawa ALLAH MAHA PEMURAH & PENYAYANG kerana mengingatkan kita bahawa dia bukanlah pilihan yg hebat untuk kita dan kehidupan kita pada masa depan...

6. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita dapat mengutip pengalaman yg tak semua orang berpeluang untuk mengalaminya.

7. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita jadi MANUSIA YG HEBAT JIWANYA.

8. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita lebih faham bahawa CINTA YG TERBAIK HANYA ADA BERSAMA ALLAH.

9. memang ALLAH sengaja menemukan kita dengan orang yg salah supaya kita LEBIH MENGENALI KEHIDUPAN YG TAK SELAMANYA KEKAL.

Wahai sahabat yg kecewa,menderita dan sengsara kerana cinta, fahamilah bahawa kehidupan kita makin sampai ke penghujungnya.

Hari esok pun kita sendiri tak pasti samada menjadi milik kita. Gapailah keredhaan ALLAH dengan melaksanakan suruhanNYA, dan meninggalkan laranganNYA..

PERCAYALAH sesungguhnya ALLAH malu untuk menolak permintaan hambaNYA yg menadah tangan meminta dengan penuh pengharapan HANYA kepadaNYA..

Friday, August 27, 2010

Neonatal and early life vaccinology

Preclinical and human vaccine studies indicate that, although neonatal immunization does not generally lead to rapid and strong antibody response, it may result in an efficient immunological priming, which can serve as an excellent basis for future responses. The apparent impairment of CD4 and CD8 T-cell function in early life seems to results from suboptimal antigen-presenting cells-T cell interactions, which can be overcome by use of specific adjuvants or delivery systems. Although persistence of maternal antibodies may limit infant antibody responses, induction of T-cell responses largely remain unaffected by these passively transferred antibodies. Thus, neonatal priming and early boosting with vaccine formulations optimised for sufficient early life immunogenicity and maximal safety profiles, could allow better control of the huge infectious disease burden in early life.


Reviewed by: Claire-Anne Siegrist
Vaccine 19 (2001) 3331-3346

Monday, August 23, 2010

Calculator Fun

Think of FOUR numbers...


For example 8 ; 3 ; 4 ; 2.


Now combine them to make the largest and the smallest number 8432 ; 2348.


Take the smaller from the larger

8432-2348 = 6084...


Make the largest and the smallest combination of this new number,
8640 ; 0468.


Subtract the smaller from the larger.
Answer: 8172.

Now do it again...

8721-1278 = 7443...

7443-3447 = 3996..

Keep going. Will you ever end at 0?



Now try these numbers 8 ; 3 ; 2 ; 6. What happens?



Friday, August 13, 2010

Vaccination Principles

IMMUNOLOGICAL PRINCIPLES OF VACCINATION

General Points
  1. B cells antigen receptors predominantly sees 3-Dimensional conformations.
  2. T cells sees processed antigen in association with MHC molecules again as a 3-D conformation.
  3. In an Antigen Presenting Cell, such as a macrophage, non-infectious proteins were endocytosed and degraded in lysosomes to peptides (endosomal pathway), some of which bound specifically to MHC II molecules. In contrast, if an agent such as a virus infected the macrophage, some newly synthesized viral antigens are likewise degraded in the cytoplasm to peptides (the cytoplasmic pathway), but these are associated with class I MHC molecules.
The different components of the immune response to infection
Antibody has 3 important functions; -
  1. It is the only means to prevent an infection by neutralization of viral infectivity. The generation of protective Ab has usually been the only response measured by vaccine developers. Generally neutralizing Ab reacts with just a few epitopes on one or two surface antigens of the infecting agent. It is ineffective if the protective epitopes are subject to pronounced antigenic drift.
  2. Infected cells which express viral antigen on their cell surface may be lysed by 2 antibody-dependent mechanisms - (a) complement pathway, or (b) antibody-dependent cell cytotoxicity.
  3. Antibody may facilitate the removal of debris (a scavenging mechanism)
The main function of effector T cells, in particular Tc cells, is to clear an infection. Although antibody can contribute to recovery from infection, T cells are the main mechanism for achieving this. The most important feature of CMI, in direct contrast to Ab, is that it responds to many peptides from an agent. Some come from proteins that are not subject to antigenic variation. This broad T cell response is an important mechanism for overcoming antigenic variation of an agent and the genetic variability of the host population. Although such an agent may bypass the protection afforded by a preformed Ab after vaccination, the cell-mediated immune response allows most people to recover from an acute infection. Infectious agents causing chronic persistent infections have found a way of escaping a cell-mediated immune response. The mechanisms include;
  1. Generation of cells that escape a cell-mediated immune response.
  2. Down regulation of MHC production in infected cells so that they are not recognized and destroyed by T cells.
  3. Infection of cells in immunoprivileged sites such as the brain.  
The typical events that occurs after an acute virus infection eg. murine influenza is as follows ;-
  1. Virus replicates in the lungs, reaches maximum titres in 4 - 5 days,and decreases thereafter. About 12 days virus can no longer be recovered.
  2. Effector Tc cell activity reaches a maximum activity after 6 - 8 days, becomes undetectable after 14 days. Tc memory cells reaches their highest level 2 - 6 weeks after infection and remain constant or decrease only slowly.
  3. The number of Ab producing cells,producing first IgM then IgG and IgA peak at about 6 weeks and then steadily decline. Maximum B cell memory is found 10 - 15 weeks after infection but decreases thereafter but some are present at 18 months.
Both Ab-secreting and memory B cells are present after infection. In contrast Tc activity is generated only whilst infectious virus is present. Memory T cells persist but require further exposure to infectious virus for reactivation. 

Requirements of a vaccine
To be effective a vaccine should be capable of eliciting the following ;-
  1. Activation of Antigen-Presenting Cells to initiate antigen processing and producing interleukins.
  2. Activation of both T and B cells to give a high yield of memory cells.
  3. Generation of Th and Tc cells to several epitopes, to overcome the variation in the immune response in the population due to MHC polymorphism.
  4. Persistence of antigen, probably on dendritic follicular cells in lymphoid tissue, where B memory cells are recruited to form antibody-secreting cells that will continue to produce antibody.
Live vaccines fulfill these criteria par excellence. Neutralizing Abs are very important. Subunit vaccines induce poor immune responses and several doses with adjuvant are required to get an adequate response. The two main functions of the adjuvant antigen are to keep the antigen at or near the injection site and to activate antigen-presenting cells to achieve effective antigen processing and interleukin production. Vaccines composed simply of one T-cell epitope and one B- cell epitope is unlikely to be effective. This is exemplified by attempts to develop a malaria vaccine.

General Principles 
The most successful immunization programs have been those directed against viral diseases such as smallpox, poliomyelitis and measles. Before embarking on any vaccination program, the need for a vaccine in a community must be evaluated. An epidemiological assessment of the incidence and severity of an infection will determine whether it is worth preventing. No vaccine is completely safe and potential benefits from immunization should be weighed against the risk of side effects. Two ingredients are needed for a successful immunization program.
  1. A safe and effective vaccine
  2. An appropriate strategy with adequate vaccine coverage
The strategy required depend on whether the aim of the program is eradication, elimination or containment. Eradication is the complete extinction of the organism in question. In elimination, the disease disappears but the organism remains. Containment is the control of the disease to the point at which it no longer constitutes a public health problem. 

When eradication or elimination is the aim, mass immunization in early life of both sexes is usually necessary. In practice, it is very difficult to achieve 100% coverage and the success of the program depends on the ability of the vaccine to interrupt transmission of the wild virus, thereby protecting the unvaccinated. When containment is the aim, selective immunization of those most at risk is normally sufficient. The usual indications for selective immunization are travel, occupational risk, outbreak control and for individuals at special risk of severe illness. Herd immunity plays little part, as the virus continues to circulate widely among the unvaccinated. In theory, selective immunization is less expensive than mass immunization. In practice, it is not always easy to identify and vaccinate those most at risk and mass immunization may be an easier option. 

Vaccination policy
  1. Varies between different countries
  2. Maternal antibodies present up to 6 months after birth, which may interfere with the induction of an effective immune response against the vaccine by the infant. This should be duly taken into account when formulating a vaccination policy.
WHO expanded program for immunization (EPI)
  1. Aimed at developing countries and initiated in 1974.
  2. Aims to control and not eradicate 6 common disease through national health programs.
  3. The six diseases are TB, DPT, polio and measles.
   
Different Types of Vaccine
Whole virus vaccines. either live or killed, constitute the vast majority of vaccines in use at present. However, recent advances in molecular biology had provided alternative methods for producing vaccines. Listed below are the possibilities;-  
  1. Live whole virus vaccines
  2. Killed whole virus vaccines
  3. Subunit vaccines;- purified or recombinant viral antigen
  4. Recombinant virus vaccines
  5. Anti-idiotype antibodies
  6. DNA vaccines
1. Live Vaccines
Live virus vaccines are prepared from attenuated strains that are almost or completely devoid of pathogenicity but are capable of inducing a protective immune response. They multiply in the human host and provide continuous antigenic stimulation over a period of time. Primary vaccine failures are uncommon and are usually the result of inadequate storage or administration. Another possibility is interference by related viruses as is suspected in the case of oral polio vaccine in developing countries. Several methods have been used to attenuate viruses for vaccine production. 

Use of a related virus from another animal - the earliest example was the use of cowpox to prevent smallpox. The origin of the vaccinia viruses used for production is uncertain. 

Administration of pathogenic or partially attenuated virus by an unnatural route - the virulence of the virus is often reduced when administered by an unnatural route. This principle is used in the immunization of military recruits against adult respiratory distress syndrome using enterically coated live adenovirus type 4, 7 and (21). 

Passage of the virus in an "unnatural host" or host cell - the major vaccines used in man and animals have all been derived this way. After repeated passages, the virus is administered to the natural host. The initial passages are made in healthy animals or in primary cell cultures. There are several examples of this approach: the 17D strain of yellow fever was developed by passage in mice and then in chick embryos. Polioviruses were passaged in monkey kidney cells and measles in chick embryo fibroblasts. Human diploid cells are now widely used such as the WI-38 and MRC-5. The molecular basis for host range mutation is now beginning to be understood. 

Development of temperature sensitive mutants - this method may be used in conjunction with the above method. 
 
2. Inactivated whole virus vaccines
These were the easiest preparations to use. The preparation was simply inactivated. The outer virion coat should be left intact but the replicative function should be destroyed. To be effective, non-replicating virus vaccines must contain much more antigen than live vaccines that are able to replicate in the host. Preparation of killed vaccines may take the route of heat or chemicals. The chemicals used include formaldehyde or beta- propiolactone. The traditional agent for inactivation of the virus is formalin. Excessive treatment can destroy immunogenicity whereas insufficient treatment can leave infectious virus capable of causing disease. Soon after the introduction of inactivated polio vaccine, there was an outbreak of paralytic poliomyelitis in the USA use to the distribution of inadequately inactivated polio vaccine. This incident led to a review of the formalin inactivation procedure and other inactivating agents are now available, such as Beta-propiolactone. Another problem was that SV40 was occasionally found as a contaminant and there were fears of the potential oncogenic nature of the virus.
 
Live vs Dead vaccines
 
Feature                 Live         Dead
Dose low high
no. of doses             single         multiple
need for adjuvant         no               yes
Duration of immunity     many years        less
antibody response         IgG,          IgA IgG
CMI                       good             poor
Reversion to virulence   possible not     possible
 
Because live vaccines replicate inside host cells, bits of virus antigen are presented to the cell surface and recognized by cytotoxic cells.

Potential safety problems
 
Live vaccines
  1. Underattenuation
  2. Mutation leading to reversion to virulence
  3. Preparation instability
  4. Contaminating viruses in cultured cells
  5. Heat lability
  6. Should not be given to immunocompromized or pregnant patients
Killed vaccines
  1. Incomplete inactivation
  2. Increased risk of allergic reactions due to large amounts of antigen involved
Present problems with vaccine development include
  1. Failure to grow large amounts of organisms in laboratory
  2. Crude antigen preparations often give poor protection. eg. Key antigen not identified, ignorance of the nature of the protective or the protective immune response.
  3. Live vaccines of certain viruses can  (1) induce reactivation, (2) be oncogenic in nature  
3._Subunit Vaccines
Originally, non-replicating vaccines were derived from crude preparations of virus from animal tissues. As the technology for growing viruses to high titres in cell cultures advanced, it became practicable to purify virus and viral antigens. It is now possible to identify the peptide sites encompassing the major antigenic sites of viral antigens, from which highly purified subunit vaccines can be produced. Increasing purification may lead to loss of immunogenicity, and this may necessitate coupling to an immunogenic carrier protein or adjuvant, such as an aluminum salt. Examples of purified subunit vaccines include the HA vaccines for influenza A and B, and HBsAg derived from the plasma of carriers.   

4. Recombinant viral proteins
Virus proteins have been expressed in bacteria, yeast, mammalian cells, and viruses. E. Coli cells were first to be used for this purpose but the expressed proteins were not glycosylated, which was a major drawback since many of the immunogenic proteins of viruses such as the envelope glycoproteins, were glycosylated. Nevertheless, in many instances, it was demonstrated that the non-glycosylated protein backbone was just as immunogenic. Recombinant hepatitis B vaccine is the only recombinant vaccine licensed at present. 

An alternative application of recombinant DNA technology is the production of hybrid virus vaccines. The best known example is vaccinia; the DNA sequence coding for the foreign gene is inserted into the plasmid vector along with a vaccinia virus promoter and vaccinia thymidine kinase sequences. The resultant recombination vector is then introduced into cells infected with vaccinia virus to generate a virus that expresses the foreign gene. The recombinant virus vaccine can then multiply in infected cells and produce the antigens of a wide range of viruses. The genes of several viruses can be inserted, so the potential exists for producing polyvalent live vaccines. HBsAg, rabies, HSV and other viruses have been expressed in vaccinia.
Hybrid virus vaccines are stable and stimulate both cellular and humoral immunity. They are relatively cheap and simple to produce. Being live vaccines, smaller quantities are required for immunization. As yet, there are no accepted laboratory markers of attenuation or virulence of vaccinia virus for man. Alterations in the genome of vaccinia virus during the selection of recombinant may alter the virulence of the virus. The use of vaccinia also carries the risk of adverse reactions associated with the vaccine and the virus may spread to susceptible contacts. At present, efforts are being made to attenuate vaccinia virus further and the possibility of using other recombinant vectors is being explored, such as attenuated poliovirus and adenovirus.   

5. Synthetic Peptides
The development of synthetic peptides that might be useful as vaccines depends on the identification of immunogenic sites. Several methods have been used. The best known example is foot and mouth disease, where protection was achieved by immunizing animals with a linear sequence of 20 aminoacids. Synthetic peptide vaccines would have many advantages. Their antigens are precisely defined and free from unnecessary components which may be associated with side effects. They are stable and relatively cheap to manufacture. Furthermore, less quality assurance is required. Changes due to natural variation of the virus can be readily accommodated, which would be a great advantage for unstable viruses such as influenza.
Synthetic peptides do not readily stimulate T cells. It was generally assumed that, because of their small size, peptides would behave like haptens and would therefore require coupling to a protein carrier which is recognized by T-cells. It is now known that synthetic peptides can be highly immunogenic in their free form provided they contain, in addition to the B cell epitope, T- cell epitopes recognized by T-helper cells. Such T-cell epitopes can be provided by carrier protein molecules, foreign antigens. or within the synthetic peptide molecule itself.
Synthetic peptides are not applicable to all viruses. This approach did not work in the case of polioviruses because the important antigenic sites were made up of 2 or more different viral capsid proteins so that it was in a concise 3-D conformation.   

Advantages of defined viral antigens or peptides include:
  1. Production and quality control simpler
  2. No NA or other viral or external proteins, therefore less toxic.
  3. Safer in cases where viruses are oncogenic or establish a persistent infection
  4. Feasible even if virus cannot be cultivated
Disadvantages:
  1. May be less immunogenic than conventional inactivated whole-virus vaccines
  2. Requires adjuvant
  3. Requires primary course of injections followed by boosters
  4. Fails to elicit CMI.  
6. Anti-idiotype antibodies
The ability of anti-idiotype antibodies to mimic foreign antigens has led to their development as vaccines to induce immunity against viruses, bacteria and protozoa in experimental animals. Anti-idiotypes have many potential uses as viral vaccines, particularly when the antigen is difficult to grow or hazardous. They have been used to induce immunity against a wide range of viruses, including HBV, rabies, Newcastle disease virus and FeLV, reoviruses and polioviruses.
 
7. DNA vaccines
Recently, encouraging results were reported for DNA vaccines whereby DNA coding for the foreign antigen is directly injected into the animal so that the foreign antigen is directly produced by the host cells. In theory these vaccines would be extremely safe and devoid of side effects since the foreign antigens would be directly produced by the host animal. In addition, DNA is relatively inexpensive and easier to produce than conventional vaccines and thus this technology may one day increase the availability of vaccines to developing countries. Moreover, the time for development is relatively short which may enable timely immunization against emerging infectious diseases. In addition,  DNA vaccines can theoretically result in more long-term production of an antigenic protein when introduced into a relatively nondividing tissue, such as muscle. 

Indeed some observers have already dubbed the new technology the "third revolution" in vaccine development—on par with Pasteur's ground-breaking work with whole organisms and the development of subunit vaccines. The first clinical trials using injections of DNA to stimulate an  immune response against a foreign protein began for HIV in 1995. Four other clinical trials using DNA vaccines against  influenza, herpes simplex virus, T-cell lymphoma, and an additional trial for HIV were started in 1996. 

The technique that is being tested in humans involves the direct injection of plasmids - loops of DNA that contain genes for proteins produced by the organism being targeted for immunity. Once injected into the host's muscle tissue, the DNA is taken up by host cells, which then start expressing the foreign protein. The protein serves as an antigen that stimulate an immune responses and protective immunological memory. 

Enthusiasm for DNA vaccination in humans is tempered by the fact that delivery of the DNA to cells is still not optimal, particularly in larger animals. Another concern is the possibility, which exists with all gene therapy, that the vaccine's DNA will be integrated into host chromosomes and will turn on oncogenes or turn off tumor suppressor genes. Another potential downside is that extended immunostimulation by the foreign antigen could in theory provoke chronic inflammation or autoantibody production.

Presentation of immunogenic proteins and peptides
Proteins separated from virus particles are generally much less immunogenic than the intact particles. This difference in activity is usually attributed to the change in configuration of a protein when it is released from the structural requirements of the virus particle. Many attempts have been made to enhance the immunogenic activity of separated proteins.   

Adjuvants
Used to potentiate the immune response
  1. Functions to localize and slowly release antigen at or near the site of administration.
  2. Functions to activate APCs to achieve effective antigen processing or presentation
Materials that have been used include;-
  1. Aluminum salts
  2. Mineral oils
  3. Mycobacterial products, eg. Freud's adjuvants
Immunostimulating complexes (ISCOMS)
  1. An alternative vaccine vehicle
  2. The antigen is presented in an accessible, multimeric, physically well defined complex
  3. Composed of adjuvant (Quil A) and antigen held in a cage like structure
  4. Adjuvant is held to the antigen by lipids
  5. Can stimulate CMI
  6. Mean diameter 35nm
In the most successful procedure, a mixture of the plant glycoside saponin, cholesterol and phosphatidylcholine provides a vehicle for presentation of several copies of the protein on a cage-like structure. Such a multimeric presentation mimics the natural situation of antigens on microorganisms. These immunostimulating complexes have activities equivalent to those of the virus particles from which the proteins are derived, thus holding out great promise for the presentation of genetically engineered proteins. 

Similar considerations apply to the presentation of peptides. It has been shown that by building the peptide into a framework of lysine residues so that 8 copies instead of 1 copy are present, the immune response induced was of a much greater magnitude. A novel approach involves the presentation of the peptide in a polymeric form combined with T cell epitopes. The sequence coding for the foot and mouth disease virus peptide was expressed as part of a fusion protein with the gene coding for the Hepatitis B core protein. The hybrid protein, which forms spherical particles 22nm in diameter, elicited levels of neutralizing antibodies against foot and mouth disease virus that were at least a hundred times greater than those produced by the monomeric peptide.   

Immunization and Herd Immunity  
The following questions should be asked when a vaccination policy against a particular virus is being developed.
  1. What proportion of the population should be immunized to achieve eradication.
  2. What is the best age to immunize?
  3. How is this affected by birth rates and other factors
  4. How does immunization affect the age distribution of susceptible individuals, particularly those in age-classes most at risk of serious disease?
  5. How significant are genetic, social, or spatial heterogeneities in susceptibility to infection?
  6. Hoe does this affect herd immunity?
A basic concept is that of the basic rate of the infection R0. for most viral infections, R0 is the average number of secondary cases produced by a primary case in a wholly susceptible population. Clearly, an infection cannot maintain itself or spread if R0 is less than 1. R0 can be estimated from as B/(A-D);B = life expectancy, A = average age at which infection is acquired, D = the characteristic duration of maternal antibodies. 

The larger the value of R0, the harder it is to eradicate the infection from the community in question. A rough estimate of the level of immunization coverage required can be estimated in the following manner: eradication will be achieved if the proportion immunized exceeds a critical value pinc = 1-1/R0. Thus the larger the R0, the higher the coverage is required to eliminate the infection. Thus the global eradication of measles, with its R0 of 10 to 20 or more, is almost sure to be more difficult to eradicate than smallpox, with its estimated R0 of 2 to 4. Another example is rubella and measles immunization in the US. Rubella (A = 9 years) has an Ro roughly half that of measles (A = 5 years) and indeed rubella has been effectively eradicated in the US while the incidence of measles have declined more slowly. 

Why do we not require 100% coverage to eradicate an infection? Immunization has both a direct and indirect effect. The susceptible host population is reduced by mass immunization so that the transmission of infection has become correspondingly less efficient and eventually, the infection will be unable to maintain itself. 

Average age
of infection
Epidemic
period
R0
Critical
coverage
Measles      4-5       2        15-17      92-95
Pertussis   4-5         3-4      15-17    92-95
Mumps 6-7   3 10-12  90-92
Rubella   9-10  3-5  7-8  85-87
Diptheria  11-14  4-6 5-6  80-85
Polio


 
12-15


3-5


5-6



80-85


adapted from: http://virology-online.com

Thursday, August 12, 2010

Viral Immunology

Viruses are strongly immunogenic and induces 2 types of immune responses; humoral and cellular. The repertoire of specificities of T and B cells are formed by rearrangements and somatic mutations. T and B cells do not generally recognize the same epitopes present on the same virus. B cells see the free unaltered proteins in their native 3-D conformation whereas T cells usually see the Ag in a denatured form in conjunction with MHC molecules. The characteristics of the immune reaction to the same virus may differ in different individuals depending on their genetic constitutions. 

Humoral response is responsible for blocking the infectivity of the virus (neutralization). Those of the IgM and IgG class are especially relevant for defense against viral infections accompanied by viraemia, whereas those of the IgA class are important in infections acquired through a mucosa. (the nose, the intestine) In contrast, the cellular response kills the virus-infected cells expressing viral proteins on their surfaces, such as the glycoproteins of enveloped viruses and sometimes core proteins of these viruses.   

Humoral Response
Abs are elicited by the surface components of intact virions as well by the internal components of disrupted virions. Also they are elicited by viral products built into the surface of infected cells or released by the cells. Antibodies provide the key to protection against many viral infections. Sometimes, they are also pathogenic e.g. immune complexes are thought to be responsible for causing the rash in rubella. Interactions of virions with Abs to different components of their coats have different consequences. 

Neutralization
virus neutralization consists of a decrease in the infectious titre of a viral preparation following its exposure to Abs. The loss of infectivity is bought about by interference by the bound Ab with any one o the steps leading to the release of the viral genome into the host cells. the consequences of the virion-Ab interaction therefore depends on many factors;-
  1. The structure of the virions
  2. The target of the Ab e.g. Abs against the HA but not the NA of influenza virus are neutralizing.
  3. Mutations affecting surface molecules that may alter the susceptibility to certain Abs
  4. The type of Ab, especially its affinity for the components of the virions
  5. The number of Ab molecules attached to the virions
Reversible neutralization - The neutralization process can be reversed by diluting the Ab-Ag mixture within a short time of the formation of the Ag-Ab complexes (30 mins). It is thought that reversible neutralization is due to the interference with attachment of virions to the cellular receptors. The process requires the saturation of the surface of the virus with Abs. 

Stable neutralization - with time, Ag-Ab complexes usually become more stable (several hours) and the process cannot be reversed by dilution. Neither the virions nor the Abs are permanently changed in stable neutralization, for the unchanged components can be recovered. The neutralized virus can be reactivated by proteolytic cleavage. Intact Abs can be recovered by dissociating the Ab- Ag complexes at acid or alkaline pH. 

Stable neutralization has a different mechanism to that of reversible neutralization. It had been shown that neutralized virus can attach and that already attached virions can be neutralized. The number of Ab molecules required for stable neutralization is considerably smaller than that of reversible neutralization, Kinetic evidence shows that even a single Ab molecule can neutralize a virion. Such neutralization is generally produced by Ab molecules that establish contact with 2 antigenic sites on different monomers of a virion, greatly increasing the stability of the complexes. 

Virion sites for neutralization - only epitopes on molecules involved in the release of the viral genome into the cells are targets of neutralization. In influenza viruses, only the HA and not the NA are targets for neutralization. In polioviruses, all antigenic sites recognizable on the capsid are targets for neutralization, because the capsid is a unit for releasing the nucleic acid. For adenoviruses, the main targets are the hexons rather than the pentons, as the hexons are strongly interconnected and work together for the release of the viral DNA. Occasionally, Abs bound to non-neutralizing epitopes can be detected by neutralization in the presence of complement, whereby the viral enveloped is attacked by the complement cascade. 

Protective role of neutralizing antibodies - the neutralizing power of a serum usually reflects the degree of protection in an infected animal. The correlation, however, is not always perfect. Discrepancies may be generated by differences in the neutralizability of a virus in the cells used for assay in vitro compared to those that the virus infects in vivo. e.g. the sera of mice protected from yellow fever did not neutralize the virus in vero cells but did so in a mouse neuroblastoma cell line. Another possible reason for discrepancy is that an Ab that does not neutralize in cultures may act in vivo by activating host responses against the virus or virus-infected cells. e.g. complement or macrophages. In addition, neutralizing Abs may fail to protect because rapid viral multiplication overcomes the neutralizing power. In the early period of immunization, low affinity Abs act predominantly by activating complement and have low neutralizing power in cultures. The degree of neutralization in cultures is probably best estimated by carrying out neutralization in the presence of complement.  

Evolution of viral antigens
Viral evolution must tend to select for mutations that change the antigenic determinants involved in neutralization. In contrast, other antigenic sites would tend to remain unchanged because mutations affecting them would not be selected for and could even be detrimental. A virus would thus evolve from an original type to a variety of types, different in neutralization (and sometimes in HI) tests, but retaining some of the original mosaic of antigenic determinants recognizable by CFTs. 

These evolutionary arguments are consistent with the observation that the clearest differentiation of types within a family is present in viruses of rather complex architecture, in which the Ags involved in the interaction with the cell vary more than other proteins. Thus enveloped viruses have a strain-specific envelope but a cross-reactive internal capsid; adenoviruses have type-specific fibers and family-specific (and also type-specific) capsomers. Moreover, the C Ag of polioviruses, which appears only after heating, reveals antigenic sites that are normally hidden and hence are not affected by selective pressure. The extent of antigenic variation differs widely among viruses and is most extensive with lentiviruses and influenza viruses.  

Types of virus-specific antibodies
Different types of viral preparations elicit the formation of different Abs;-
  1. Killed virus preparations elicit Abs predominantly directed against the surface of the virions. These Abs have neutralizing and HI activities against the virions as well as CF and precipitating activities against the Ags of the viral coat.
  2. Live virus preparations elicit antibodies against all the viral antigens, including both external and internal antigens.
  3. Immunization with internal components of the virions produces CF and precipitating Abs active only toward the Ags of these components.
  4. Immunization with peptides reproducing segments of virion proteins elicit Abs, the properties of which depend both on the protein and the specific sequences reproduced.    
Specificity of test methods
The Abs that react in the different tests may overlap though they may not be altogether identical. Neutralization is primarily caused by Ab molecules specific for the sites of the virion that are involved in the release of viral nucleic acid into the cell. CF usually involves additional surface or internal Ags. Neutralization probably requires molecules with a higher affinity for virions than do HI and CF. After viral infection, the titres of Abs to different components rise and fall with quite different time courses. 

Because of their high specificity, immunological methods can differentiate not only between viruses of different families but also between closely related viruses of the same family or subfamily. By these means, family Ags may be identified. Usually, antibodies detected by neutralization tend to be less cross-reactive and thus are useful in defining the immunological type. Whereas those detected by CF tend to be more cross-reactive and the useful in defining the family. By proper procedures, however, such as immunization with purified Ags, highly specific CF Abs can be prepared. 

The resolving power of Abs is maximized by the use of monoclonal Abs. Whereas all the methods for measuring viral antigens are needed for classifying a new isolate, the method of choice for diagnostic purposes is ELISA, for its high sensitivity and low cost.    

Cell-Mediated Immunity 
Cytotoxic T lymphocytes
CMI is very important in localizing viral infections, in recovery, and in the pathogenesis of viral diseases. In experimental animals, primary CTLs reach maximal abundance about 6 days after a viral infection and then disappears as infection subsides. However, memory T cells persists and can be recognized by culturing spleen cells with virus-infected cells where within a few days, secondary CTLs appear in culture with much greater activity than in the initial response. 

Formation of CTLs is elicited by cell-associated Ags present at the cell surface, not only for enveloped viruses, but also for other viruses whose core or nonvirion proteins reach the cell surface. As in humoral immunity, type specific and group specific responses can be seen. Even noninfectious or inactivated viruses can elicit a cellular response because their envelopes fuse with the cell plasma membrane in the initial stage of viral penetration. Moreover, the virions themselves may also be able to elicit the response after absorbing to the macrophages. Both internal virion proteins and nonvirion proteins are often recognized by CTLs. An example is the nucleocapsid proteins of enveloped viruses, fragments of which reach the cell surface by an unknown route and are recognized very efficiently, giving rise mainly to cross-reactive CTLs. Often, Abs to viral surface proteins do not block their interaction with CTLs, because the humoral and cellular responses recognize different epitopes.

Antibody-dependent cell-mediated cytotoxicity
The K cells are the effector cells in ADCC. In vitro, these cells kill virus-infected cells sensitized by IgG from immune donors but not unsensitized targets. ADCC is very efficient in vitro against HSV or VZV infected cells, preventing the usual spread of the virus from infected to neighboring uninfected cells. Therefore, it may play a role in the defense against human infection with these viruses. K cells had been shown to mediate immunity to vaccinia infection rather than Tc cells.   

Natural Killer (NK) cells
In man, the principal NK cell is the large granular lymphocyte (LGL) which comprise 2-5% of peripheral blood lymphocytes. However, not all lytic cells are LGLs and not all LGLs are NK cells. There is overlap of the NK population with K cells. The Fc receptor of the NK cell is however, not involved in the lytic process. There are also mechanistic differences and K cell activity is less consistently augmented by interferon and other immune modulators. NK activity is subject to both positive and negative regulation in vivo and in vitro. Interferon gamma and IL-2 are potent inducers. Besides producing lysis, NK cells can produce alpha-interferon. 

The target molecules recognized but NK cells have not been defined but it appears that some determinants are ubiquitous whilst others have a more restricted distribution. An alternative suggestion is that NK cell susceptibility depends on the absence of normal cell surface antigens such as MHC molecules. The importance of NK cells in viral infection is partially understood. It had been shown that mice depleted of NK cells by treatment with Ab against asialo GM1 show an increased susceptibility to CMV.


adapted from: http://virology-online.com/general/Immunology.htm

Monday, August 2, 2010

Panduan Dasar Hafazan Al-Quran

Di sini disertakan panduan dasar untuk hafazan al-Quran. Antara panduannya:

1. Tanamkan di hati kepentingan al-Quran.

Ulasan : Mulakan niat yang waja untuk menghafal ayat-ayat al-Quran sehingga sepanjang hayat. Niat pun sahaja dah dapat pahala.

2. Mesti sentiasa bersikap positif, sebaliknya jangan sekali-kali menyatakan susah.
Ulasan : Sebenarnya, apa yang fikir dan cakap adalah dianggap doa. Anda adalah apa yang anda fikirkan. Anda adalah apa yang anda cakapkan. Itulah anda!

3. Hafaz satu ayat secara perlahan-lahan dan baca dengan jumlah yang banyak ... sekurang-kurangnya 60 kali.

Ulasan : Kemahiran mengulang dalam hidup anda perlu dihidupkan semula. Ramai orang tak suka mengulang.Mengulang yang baik adalah digalakkan.

4. Jangan berpindah ke ayat yang lain sebelum ayat yang dihafaz betul-betul lancar.

5. Jangan tergesa-gesa hendak menghafaz kerana ini akan menjadi musuh kepada istiqamah atau berterusan.


6. Bersabar, bersabar dan terus bersabar. Menghafaz melatih kita bersabar. Satu latihan yang bernilai bagi kita untuk menghadapi cabaran hidup.

7. Tujuan menghafaz supaya ianya kukuh dan mudah diulang yang mana meningkatkan nikmat membaca.

8. Kuatkan azam dan tekad untuk menghafaz ayat-ayat al-Quran.


Sumber Rujukan: Mohd. Shafie Md. Amin.2001. Kaedah Sistematik Menghafaz. Ampang: Penerbitan Salafi.

Saturday, July 31, 2010

Solat, Ubat Mujarab Pengusir Kesedihan

Apabila ketakutan meliputi kita, juga kesedihan menghimpit kita dan kerisauan mencengkam jiwa kita, maka bersegeralah kita mendirikan solat, nescaya jiwa kita akan kembali tenteram dan tenang. Sesungguhnya, solat itu-atas izin Allah-mudah-mudahan boleh menjaga kita dengan menghilangkan kesedihan dan kerisauan yang menghimpit kita selama ini.

Sesungguhnya apabila setiap kali dirundung kegelisahan, Rasulullah s.a.w. selalu meminta kepada Bilal ibn Rabbah, "Tenangkanlah kami dengan solat, wahai Bilal." (Hadith). Begitulah, solat benar-benar merupakan penyejuk hati dan sumber kebahagiaan bagi Rasulullah s.a.w.

Bagi generasi umat manusia yang sedang banyak menderita penyakit kejiwaan seperti saat ini, sebaiknya hendaklah sering mengunjungi masjid dan menghamparkan keningnya di atas lantai tempat sujud dalam rangka meraih keredhaan Allah. Dengan demikian, nescaya ia akan selamat dari pelbagai himpitan hidup. Jika tidak, tangisannya itu tentu akan membakar kelopak matanya dan kesedihan akan menghancurkan urat sarafnya. Maka jelaslah bahawasanya, seseorang itu tidak memiliki kekuatan pun untuk meraih ketenangan dan ketenteraman hati selain dengan mendirikan solat.

Salah satu daripada nikmat Allah yang paling besar (sekiranya kita berfikir) ialah pelaksanaan solat wajib lima waktu dalam sehari semalam, yang merupakan ubat yang paling mujarab untuk mengubati pelbagai kesedihan dan pelbagai macam penyakit yang kita deritai. Betapapun, solat mampu meniupkan ketulusan iman dan kejernihan iman ke dalam relung hati, sehinggalah hati selalu redha dengan apa jua ketentuan Allah.

Adapun bagi mereka yang menjauhi masjid dan meninggalkan solat, maka mereka hanya akan beralih dari kesusahan yang satu kepada kesusahan yang lain, dari goncangan jiwa yang satu kepada goncangan jiwa yang lain dan dari kesengsaraan yang satu kepada kesengsaraan yang lain.


dipetik dari kitab LA TAHZAN, Dr. Aidh Abdullah Al-Qarni.

Friday, July 30, 2010

Menghargai Pengorbanan Pahlawan

Pahlawan adalah benteng negara, tanpa pahlawan, negara sentiasa terdedah dengan ancaman musuh, maka kerana itu kalau kita sayangkan negara, kita mestilah sanggup memberi pengorbanan untuk mempertahankan negara daripada musuh yang menggugat keselamatan dan segala bentuk pencerobohan dan penjajahan.

Tanggungjawab menjaga keselamatan negara adalah tanggungjawab setiap rakyat. Islam mengajar kita supaya cintakan negara, kerana cintakan negara itu sebahagian daripada tanda adanya iman. Menjaga negara tidak hanya sekadar menjaganya dari serangan musuh yang menggugat keamanan, tetapi juga dalam pengertian yang lebih luas, iaitu menjaga maruah negara dari segala anasir yang boleh merosakkan akidah, syariah, akhlak dan pemikiran rakyat, yang akhirnya akan menghancurkan kebahagiaan hidup seluruhnya.

Islam banyak menampilkan serikandi pahlawan muslimatnya, seperti Aisyah Ummu Salim, Ummu Ruqaidah, Ummu Ziyad, Asiah dan Ummu 'Attiya dan anak perempuan Mu'az (Rabi') yang menjadi pahlawan serikandi dalam Peperangan Khaibar dan tujuh peperangan yang lain. Dalam Peperangan Khandaq, Safiah (ibu saudara Rasullullah s.a.w.) dengan sebatang kayu tampil menyerang dan membunuh Yahudi Bani Quraizah. Sabda Rasullullah s.a.w. yang bermaksud:

"Berjuang di jalan Allah satu hari, lebih baik daripada dunia dan apa yang ada di atasnya."
(Riwayat Al-Bukhari)
Hadith tersebut membuktikan bahawa mereka yang gugur dalam mempertahankan akidah, syariah, akhlak Islam, dan kedaulatan hukum-hakam Allah, sebagai syahid dan kehidupan mereka dinilai tinggi lebih dari nilai dunia dan segala isinya.

Pahlawan terbilang bukan sahaja dari kalangan tentera bersenjata, tetapi ia juga dari kalangan pemimpin-pemimpin yang ikhlas berjuang di jalan Allah, ulama'-ulama' yang bertanggungjawab dan amanah dalam menyedarkan masyarakat tentang mulianya berjihad mempertahankan negara atas dasar agama tanpa mengira bangsa, keturunan dan pangkat. Akan tetapi perjuangan atas dasar fahaman 'assabiyah dan perkauman dilarang oleh Islam, perjuangan kerana merebut harta, nama atau kedudukan yang baik, tidak kira sebagai pahlawan yang berjuang di jalan Allah.

Sabda Rasullullah s.a.w.:

"Katakan kepada Rasulullah s.aw. ada pahlawan yang berperang kerana mengharapkan harta, ada pahlawan yang berperang untuk mendapat kemasyhuran dan ada pahlawan yang berperang supaya diberi jawatan atau kedudukan yang baik, maka yang mana satukah pejuang di jalan Allah? Nabi menjawab; sesiapa yang berperang meninggikan kalimah Allah yang tinggi, maka dialah sebenar-benar pahlawan yang berjuang di jalan Allah."

sedutan khutbah JAIS

Tuesday, July 27, 2010

Memelihara Lidah

Antara anggota penting manusia yang wajib diberikan perhatian adalah lidah. Tanpa lidah manusia tidak dapat menuturkan kata-kata dengan baik. Dengan lidah juga manusia dapat bermain kata-kata. Dengan lidah juga manusia dapat menghancurkan segala-galanya. Kerana pentingnya lidah, ia harus dijaga supaya tutur kata yang keluar daripada lidah tidak mendatangkan kesan buruk kepada orang ditutur dan tidak memperondak-randakan masyarakat.


Walaupun lidah hanya anggota yang kecil dan tidak bertulang, tetapi ia mempunyai peranan yang besar dalam kehidupan manusia. Lidah boleh memartabatkan seseorang manusia. Seringkali manusia dimuliakan kerana lidahnya. Lidah juga boleh menjatuhkan seseorang manusia dan seringkali manusia hina kerana lidahnya.


Pendek kata, lidah boleh menaikkan imej seseorang dan lidah juga boleh menjatuhkan seseorang dalam sekelip mata. Sebab itu lidah boleh membawa kebahagiaan dan lidah juga boleh membawa kebinasaan kepada seseorang. Bak kata pepatah, "sebab pulut santan binasa, sebab mulut badan binasa."  


Jika kita perhatikan kepada perbualan para remaja dan muda-mudi kita sekarang, kita akan dapati bahawa perbualan mereka tidak lengang dari perkataan lucah dan kotor, memaki satu sama lain, mencarut, sama ada secara sedar atau tidak sedar, sama ada secara sungguh-sungguh atau main-main.


Kemudian kita bandingkan pula perbualan kita sesama kawan rapat kita di pejabat. Kita perhatikan kadang-kadang perkataan-perkataan yang kita ucapkan tersebut juga mempunyai unsur-unsur umpatan dan pembohongan ataupun seumpamanya. Kemudian kita juga perhatikan perbualan dan percakapan masyarakat kita seharian. Nescaya kita akan dapati percakapan mereka bercampur dengan unsur-unsur kata-mengata, umpat-mengumpat, caci-mencaci, fitnah-memfitnah dan sebagainya yang boleh menyakitkan hati orang yang diumpat.


Dalam hal ini, Allah s.w.t berfirman di dalam surah An-Nisaa, ayat 114 bermaksud:


"Tidak ada gunanya pada kebanyakan dari bisikan-bisikan mereka melainkan sesiapa yang menyuruh memberi sedekah, atau berbuat baik, ataupun mengadakan perdamaian antara bangsa manusia. Dan barangsiapa yang melakukan demikian kerana mengharapkan keredhaan Allah maka Kami (Allah) akan memberinya ganjaran yang besar."


Allah s.w.t dengan tegas mengatakan bahawa perbualan dan percakapan manusia menjadi sia-sia saja kecuali pada tiga perkara iaitu:

  1. Menyuruh orang memberi sedekah
  2. Menyuruh orang berbuat baik
  3. Mendamaikan antara dua pihak yang bergaduh.

Sebab itu, perbualan umum antara manusia seperti berborak-borak, bergurau-senda yang berlebihan, menceritakan hal orang dan sebagainya adalah satu perbuatan yang sia-sia, malah boleh mendatangkan dosa. Mungkin antara punca mengapa bangsa kita masih tidak bersatu dan bersepakat, kerana punca lidah kita sendiri yang mendoakan agar diri kita diberikan bencana. Tutur kata kita yang melahirkan permintaan begitu.

Perbualan seharian kita diselangi dengan perkataan kotor, kita sulami dengan maki-hamun. Walaupun ia tidak disengajakan, walau ia tidak dimaksudkan, akan tetapi secara tidak langsung kita telah mendoakan sesuatu keburukan kepada saudara kita. Ini bukanlah ajaran Islam. Ini bukan juga adab seorang Muslim. Dan ini bukanlah dari didikan Rasulullah s.a.w.


Kita mengaku bahwa kita cintakan Rasulullah s.a.w. Kitalah orang pertama sekali menentang jika ada sesiapa yang cuba merendah-rendahkan serta menghina Rasulullah s.a.w. Akan tetapi cinta kepada Rasulullah s.a.w. itu tidak disertakan dengan perbuatan kita. Kita ketepikan sifat-sifat baik yang ada pada Rasulullah s.a.w. yakni kita tidak meniru adab dan akhlak-akhlak terpuji Rasulullah s.a.w.


Kerana itu, kita seharusnya menjaga lidah kita agar tidak mengeluarkan perkataan yang sia-sia, apatah lagi kata-kata yang boleh menjatuhkan maruah seseorang dan meninggalkan kesan yang mendalam terhadap dirinya. Ini jelas dari hadith Rasulullah s.a.w. yang bermaksud:

"Jagalah lidahmu kecuali bila berkata yang baik. Dengan berlaku demikian engkau akan mengalahkan syaitan."

Dan sabda Rasulullah s.a.w. lagi:
"Barangsiapa beriman kepada Allah dan Hari Akhirat, maka berkatalah yang baik ataupun berdiam saja."


Antara bencana lidah adalah berbohong. Memang kita sudah ketahui akan dosa berbohong tetapi kadang-kadang kita melakukannya apabila kita berborak-borak dengan teman-teman. Kita mengada-adakan cerita untuk menjadi bahan ketawa. Kita menambah-nambah cerita orang lain untuk menjadi lebih menarik. Ini bukan sahaja membawa dosa mengumpat, bahkan ia membawa dosa fitnah.


Dan fitnah itu adalah lebih besar dosanya dari membunuh. Lihatlah contoh Rasulullah s.a.w. BAginda juga bergurau-senda dan bergembira dengan isteri-isterinya, tetapi baginda tidak pernah mengadakan suatu yang palsu dalam gurau sendanya. Rasulullah s.a.w. bersabda:

"Aku pun turut bergurau-senda, tetapi aku tidak mengatakan sesuatu melainkan yang benar belaka."


Inilah akhlak Rasulullah s.a.w. Maka kita seharusnya cuba mencontohi baginda. Marilah kita jauhkan diri kita dari berkata-kata yang sia-sia, berkata yang tidak benar dalam senda gurau. Berkata Ibnu As kepada puteranya:

"Wahai anakku! Jangan engkau berani bergurau-senda dengan orang yang berpangkat kelak ia akan memusuhi kamu.  Dan jangan pula kepada orang yang rendah budi, kelak ia akan kurang ajar terhadapmu."


sumber: www.baheis.islam.gov.my