The World AIDS Conference is in full swing in Vienna, Austria this week, with the leading researchers in HIV/AIDS gathered to present their most recent research. We spoke yesterday with our esteemed HIV/AIDS expert, Dr. Raphael Landovitz, MD, Assistant Professor in the Division of Infectious Diseases at the Center for Clinical AIDS Research & Education at the University of California, Los Angeles, who is at the conference. We asked him about the findings being presented there, and where the next developments in HIV/AIDS research are likely to appear.
The highlight of the week was a study called CAPRISA 004 (CAPRISA stands for Center for the AIDS Program of Research in South Africa), which tested an antimicrobial gel containing an antiretroviral medication called tenofovir. Says Dr. Landovitz, "This study was conducted at two sites in South Africa, one urban and one rural. It followed 889 women in a placebo-controlled, randomized trial, meaning that the women were randomly assigned to receive either the tenofovir gel or a placebo. They received montly HIV testing and sexual risk-reduction counseling. They were instructed to use the gel within 12 hours of anticipating having sex, then as soon as possible within 12 hours after having sex.
After 30 months, the researchers found that there was an overall 39% reduction in HIV transmission, which was highly satistically significant." And, Dr. Landovitz tells us, in the people who adhered most closely to the protocol, and used the gel with the greatest regularity, the effect was even higher. "In people who used it at least 80% of the time," Dr. Landovitz says, "the gel was 54% effective. This suggests that perhaps with better adherence you could get even greater results—and it’s probably not reasonable to expect a product to provide protection if you don’t use it."
The study had a second very promising finding: "In addition, there was an unexpected finding of a 50% protection against Herpes type 2, or HSV-2. This is important because people who have HSV-2 double the risk of acquiring HIV infection; because it causes “ulcers,” or breaks in the genital lining, it compromises the body's natural defenses, making HIV infection more likely. So if we can prevent HSV-2, we may get even better HIV prevention. In fact, this suggests that the 30-month result may actually be an underestimate of what is possible from the combination of HIV prevention immediately, and longer term HIV protection which not having HSV-2 confers.”
Though the CAPRISA study was conducted only with women, its findings are very important for gay men, both in the US and in the developing world. "This study," Dr. Landovitz says, "is a first proof of principle that topical application of a lubricant-based antiviral around the time of sex can actually prevent HIV and HSV-2." Previously developed microbicides—remember nonoxynol-9?—were disappointments, even in some cases increasing the risk of infection. This new study is, Dr. Landovitz says, the first time anyone has demonstrated that this method can be effective. "What we don't yet know," he says, "is whether this can work in a rectal environment as well; the rectum, unlike the vagina, is not a closed system. And, whereas the vagina has a very developed set of immune defenses, the rectal lining is only one cell-layer thick and therefore much more vulnerable. So the next step will be to try to find out this kind of lubricant can have a protective effect with anal sex—in both men and women—and those studies are in progress, or being designed." And even if it does, Dr. Landovitz warns, this will not be a replacement for condoms, rather a supplement to them.
Research presented at the conference concerning men who have sex with men (MSM) sheds light on the importance of the CAPRISA study. Dr. Joseph Barker of the Centers for Disease Control and Prevention (CDC) presented research conducted in Uganda, where homosexuality is illegal. This was, Dr. Landovitz says, potentially very dangerous research for both scientists and subjects, and was conducted on an MSM population about whom very little is known, precisely because they face such risks. "This research found," Dr. Landovitz says, "that in Kampala, HIV prevalence in men is 4.5%; in women it's 8.5%; and in MSM it's 14%." That is a devastating number—but consider this: "Of those men, about a third were married, and many lived with women and/or had sex with women on an ongoing basis." Access to effective antiretroviral gel that men and women alike could use privately, without needing to negotiate with a partner (of either sex), could prove substantially effective in slowing the spread of HIV in both the MSM and heterosexual populations.
The limitation, though, may be education. "In a country like Uganda," Dr. Landovitz says, "MSM may be an important bridge population in HIV transmission, and they're only beginning to be assessed. This is a complicated and difficult process, and will remain so as long as MSM are criminalized. MSM are not even part of some countries' AIDS strategies, which means that there is little access to accurate epidemiologic information, and an alarming finding in Dr. Barker’s study was that MSM have quite poor literacy on HIV and how it is transmitted. This may fuel high HIV transmission rates and makes education that much more important; it also makes this kind of research really critical, because in order to change policy toward MSM in Africa, you first have to prove that they are there, and at risk." Overall, Dr. Landovitz says, accumulating that evidence is an ongoing coordinated effort of NGOs (non-governmental organizations) and the CDC working in these countries along with MSM communities and civil and human rights groups.
In general, these two findings reflect what Dr. Landovitz sees as a progressive sea-change in emphasis within the HIV/AIDS research community. "Overall, there's been a shift in focus at the large AIDS conferences," he says, "which used to be heavily concentrated in new treatments. We’ve gotten quite good at treating HIV, and studies now demonstrate incremental refinements and improvements in treatment, and improvements in our understanding of side effects, both long and short term. But there's less new drug development. Instead, you see more focus on HIV prevention strategies, which is very exciting, and even cure—though we remain far from that." But every day a little closer.