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GUEST EDITORIAL
Year : 2003  |  Volume : 21  |  Issue : 4  |  Page : 224
 

AIDS vaccine - Is there light at the end of the tunnel?


Jhaveri Microbiology Centre, L.V. Prasad Eye Institute, L.V. Prasad Marg, Banjara Hills, Hyderabad - 500 034, India

Correspondence Address:
Jhaveri Microbiology Centre, L.V. Prasad Eye Institute, L.V. Prasad Marg, Banjara Hills, Hyderabad - 500 034, India



How to cite this article:
Hari R. AIDS vaccine - Is there light at the end of the tunnel?. Indian J Med Microbiol 2003;21:224


How to cite this URL:
Hari R. AIDS vaccine - Is there light at the end of the tunnel?. Indian J Med Microbiol [serial online] 2003 [cited 2019 Nov 19];21:224. Available from: http://www.ijmm.org/text.asp?2003/21/4/224/8032


HIV infection has made deep inroads as a major threat to global health and development. Combating HIV has become an overwhelming focus in healthcare policies for many Governments particularly in the developing world and their economies. Several publications on HIV in this issue of IJMM in a way point to the magnitude of the problem in India. In the present issue, two articles on HIV seroprevalence among intravenous drug users who are a high risk population, has been highlighted from Delhi and Orissa, while a follow-up study done on HIV patients under HAART therapy has been evaluated from CMC, Vellore, Tamil Nadu. It is well known that AIDS kills more people than any other infectious disease, and in view of the problems seen with antivirals against HIV, only an AIDS vaccine can prevent the HIV pandemic. In the present context, the article on HIV vaccines - a ray of hope, published in the present issue, highlights the various vaccines which have been evaluated and also the studies and trials currently going on in our country.
The major barriers that thwart the production of HIV vaccines are the fact that HIV mutates rapidly and does not express itself in all the cells. Moreover, the virus is not completely cleared by the host immune response after primary infection. HIV isolates from different geographical regions show variation in their envelope antigens and this has resulted in many neutralization resistant mutants. The recent focus of development of HIV vaccines is targeted towards developing neutralizing antibody responses. The inability of developing broadly neutralizing antibodies in HIV vaccines might also be due to the unusual structures of the antibodies, which are generated against gp120 of HIV.
Among the animal viruses that are currently under study, SIV virus 89.6P is used as the challenge strain in non-human primate studies.[1] This strain is being used because it produces a typical course and ease of neutralization, but it may not be predictive of protection against clinical isolates. Macaques immunized with adenovirus vectors encoding SIV Gag and SIV Env gene provide better protection than that with either antigen alone. These studies on non-human primates although encouraging, lead us to the question of whether it can be extrapolated to humans. Recently, few of the research groups in Japan are now studying NKT cell Ligand (a Galcer) and fusion proteins of CTLA4 and SIV Gag as potential molecular adjuvants.
In addition to extensive research on prophylactic vaccination, therapeutic vaccination in combination with recombinant vectors expressing HIV-1 env, gag, and nef genes is also being studied. The initial results are encouraging but clinical benefits have to be realized. Another important concern is the emergence of CTL escape mutants of the virus, which may nullify the effect of the vaccine. Induction of virus specific CD4 and T cell responses in absence of effective immune response might accelerate or impede disease progression, which is another concern that has to be addressed in our quest for an AIDS vaccine.
Among the vaccines that are currently being evaluated are the Vaxgen and the Merck vaccine study which has entered the phase III stage. DNA priming with recombinant adenovirus vector boost are promising encouraging results but still efficacy trials are several years away.
Are we addressing the question of HIV subtypes adequately in our quest for developing a vaccine, which can be used throughout the world? Should we not focus on newer targets on the virus for a much better vaccine? Are we trying to develop HIV vaccines that can be suitable to tropical countries in terms of stability and cost?
These are some of the prime questions, which needs to be addressed in order to develop an HIV vaccine for Asia, particularly India. India too is in the reckoning towards developing a HIV vaccine against subtype C, which is the more prevalent subtype. Even a partially effective vaccine would still be advantageous as Salk Polio vaccine introduced in 1955 proved to be only 60% effective in prevention of polio. Can newer approaches, like HIV negativity observed in highly exposed persistently seronegative individuals (HEPS) and development of a conditional live virus where replication can be switched on and off at will, provide answers for the elusive HIV vaccine, only time will tell. It is therefore, pertinent that a pandemic like AIDS can be prevented only with a safe and effective vaccine, which is very near yet so far. At last, will there be light at the end of the tunnel? 

 ~ References Top

1.Kaur A, Johnson RP. HIV pathogenesis and vaccine development. In: Topic in HIV Medicine . Conference highlights - International AIDS Soceity - USA. Vol.II Issue 3, May/June 2003.  Back to cited text no. 1    
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2004 - Indian Journal of Medical Microbiology
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