I am often asked why HIV/AIDS is such a problem and why there isn’t a vaccine or even a cure in sight after 30+ years of the epidemic. The simple answer regarding a preventative vaccine is that although it is fairly simple to generate a vaccine using the wonders of modern genetic engineering, it is very difficult to ethically test a vaccine to demonstrate that it works! Think about it. Would you volunteer to be a recipient of a new experimental HIV vaccine? Even if the vaccine carried no risks of untoward side effects, exposure to it would render your immune system no longer virgin territory, so that testing for the possibility of HIV infection by surveying for HIV antibodies would no longer be possible. Also, it is unethical to test the efficacy of the vaccinees by exposure to HIV! Therefore, the only avenue available for vaccine experimenters is to wait to see whether you might become infected ‘naturally’. That might take a decade, a lot of volunteers and a lot of money! Therein lies the HIV vaccine problem. The solution lies in devising a therapeutic vaccine a la Pasteur’s rabies vaccine, because it is much easier to test vaccine efficacy in individuals who are already infected, by simply discontinuing their anti-retroviral drugs for a brief period, 3-6 months, to see if the immune system can contain the residual virus, and prevent it from replicating. If so, then this would be the vaccine to move into prophylactic clinical rials in normal volunteers.
The ‘cure’ problem is even more vexing. Most current HIV scientists and clinicians feel a priori that a cure is impossible, in that if one has become infected, it is because the natural immune system has failed, and therefore one cannot hope to ever eradicate the virus from the body. However, therein lies the problem. After many infections, especially from the herpes virus family, the immune system never completely clears the virus. Instead, the immune system keeps the virus in a latent, or hidden state. Thus, in order to work towards a cure, the therapy must be directed toward repairing and enhancing the function of the immune system, so that after the anti-retroviral drugs have reduced the viral ‘load’ to a very low level, the immune system can keep it that way, in a latent, non-dangerous state.