HIV Vaccine?

The gold standard in HIV research has always been to find a preventive treatment, like a vaccine, which would thwart the virus before it could do harm. Many attempts at vaccines and chemoprophylaxis showed mixed and uninspiring results. These poor results caused many to feel that a successful HIV vaccine was impossible. However, results from a recent study in which two HIV vaccines were combined to give a synergistic effect showed moderate success in preventing HIV transmission to uninfected individuals in Thailand.
The trial combined two vaccines which previously failed in clinical tests, AIDSVAX and ALVAC, and resulted in only 51 of the 8197 HIV negative volunteers being infected with the virus (as opposed to 74 of the 8198 administered placebo injections). ALVAC contains three synthetic HIV genes attached to a bird virus vector, and is used to “prime” the human immune system, while AIDSVAX consists of an engineered protein present on HIV’s surface, which is thought to “boost” the immune response. While the 30% efficacy rate is encouraging, it is far from being clinic ready, especially since researchers do not fully understand the pharmacology of the two vaccines in tandem.
ALVAC is intended to activate the immune system by eliciting a T cell response (probably killer T cells), while AIDSVAX is designed to produce an antibody response to the synthetic epitope it presents. The combination can therefore seemingly stimulate the immune system to get ready for a fight (ALVAC) and then show the system’s competitor (AIDSVAX). However, many more experiments need to be done to show that this is indeed the pharmacological mechanism.
Additionally, a major concern is that the trial was down entirely with Thai people, with vaccines targeted at the virus mutation most often seen in that country. Before the vaccine can be world ready, it must be tested in different ethnic populations, and it must be shown that different region-specific virus mutations can be incorporated and be effective in the vaccines. Finally, although a 30% benefit is encouraging, the vaccine combination must be closer to 80 or 90% effective before it can be considered clinic ready.


Unfortunately, the article presenting this data has yet to be published (to my knowledge). Information and statistics taken from two online news articles: http://blog.newsweek.com/blogs/thehumancondition/archive/2009/09/24/good-news-from-the-hiv-vaccine-trial-the-maybe-cure-that-almost-wasn-t.aspx and http://www.startribune.com/lifestyle/health/61062722.html?elr=KArks:DCiUMEaPc:UiacyKU7DYaGEP7vDEh7P:DiUs