AIDS Research Reaches Turning Point
Siliciano warns that it remains to be seen how long vaccine-elicited immune responses can keep HIV in check. "The vaccination gives the immune system a head start on the virus," he says. "It's not entirely clear that this vaccine-induced head start will have a significant effect over the long term. It is hard to know. On the one hand, you might say that because you are able to protect against such a highly pathogenic virus in the monkeys, the vaccine may do well against HIV. But another way to look at it is that over the long course of HIV infection, the little head start isn't going to make that much of a difference."
Ahmed, however, believes that what works in monkeys against the fast-acting monkey/human virus is likely to work against the slower HIV in people. "For something to work against a strong virus and not to work against a wimpy virus -- that goes against everything we know about vaccinology," he says.
Also impressed by the Letvin team's results is Harriet Robinson, PhD, chief of microbiology and immunology at Yerkes Regional Primate Research Center in Atlanta. "I think it's a very solid study -- and very encouraging," Robinson tells WebMD.
Using a DNA vaccine similar to Letvin's -- but using an HIV-carrying smallpox vaccine instead of the immune-boosting protein -- Robinson's team recently reported early results suggesting that vaccinated animals remained healthy despite infection with the same monkey/human virus.