Treatment Issues: Newsletter of Current Issues in HIV/AIDS - Volume 20, Numbers 8, 9, 10, 11, & 12, August / December 2006
Bob Huff

The Conference on Retroviruses and Opportunistic Infections (CROI) is the most important AIDS science meeting of the year. The conference organizers run a tight ship, with attendance generally limited to working scientists and a sprinkling of community members involved with treatment advocacy and education. But exceptions are made. There are no pharmaceutical company pavilions, free pens, or slick sales pitches at CROI, but at $10,000 a head, pharma marketing personnel are allowed to purchase the right to register alongside the scientists and discreetly haunt the conference corridors offering gentle spin. I recognized at least a quarter-million dollars worth of pharma folk inside the hall. Considering that a single company's graffiti-proof exhibition can cost that much, CROI's low-profile access plan must seem like a bargain.

Yet as exclusive at CROI is, it is also the most accessible HIV meeting of the year, owing to a commitment to Webcast nearly every important session on the Internet. This year over 61 hours of plenary talks, symposiums, and special sessions are available for free viewing at www.retroconference.org. The Webcasts offer audio and synchronized slides for those with slow Web connections and streaming video plus slides on speedier hookups. New this year are MP3 and iTunes-compatible audio downloads for your podcast listening pleasure as you sit in traffic during the drive to work.

If you want to lift the veil on the state of HIV research, these Webcasts let you see and hear the people and ideas that represent the latest understanding on nearly every aspect of the virus and the immune system. You may not understand everything you hear, but if you are truly curious about what makes HIV and your immune system tick, then many of these sessions will be fascinating and informative.

Here are some random samples of CROI 2007 on the Web:

Workshop for New Investigators, Parts 1 & 2
Sunday, 8:00 a.m.
Each year a group of leading HIV researchers organizes a special session designed to acquaint younger scientists with some of the critical unanswered questions about HIV and to entice them into making HIV their career. These presentations offer a capsule overview of some of this year's hot topics, including how the body innately combats HIV, and how HIV sidesteps these defenses.

Breast Is Best
Plenary
Monday, 8:30 a.m.
Hoosen Coovadia created a buzz when he proposed that—despite the mounting, month-by-month risk of HIV transmission to infants through breastfeeding after escaping HIV infection at birth—the alternative to population-wide breastfeeding is a dramatic increase in childhood diarrhea and death. In fact, at six months, the risk of acquiring HIV through breast milk is roughly equal to the risk of having life-threatening diarrhea from formula feeding. Another surprising fact is that women with higher CD4 cell counts are less likely to transmit HIV to their infant; therefore antiretroviral therapy for the mother who breastfeeds is an effective way of protecting her infant. And exclusive breastfeeding (no water, no juice) during the first six months of life is more healthful—and more protective from HIV—than mixed feeding. The challenge, he says, is to make breastfeeding safe for HIV-positive women.

Issues in Prevention of HIV Transmission and ART
Monday, 10:00 a.m.
Eileen Dunne reported on a placebo-controlled trial in Thailand that found reduced levels of HIV shedding in vaginal fluids in women who were receiving acyclovir as suppressive therapy for herpes simplex virus. Despite a significant reduction in HIV shedding while on acyclovir, the potential impact of this intervention on preventing HIV transmission is speculative. Nevertheless, the possibility of reducing infectiousness with a simple and inexpensive drug in women without access to antiretrovirals is provocative.

Kate Scott reported on a study of San Francisco gay men that found a predictable prevalence of untreated Chlamydia and gonorrhea in men with newly acquired HIV infection. In the era of rapid HIV testing, Scott says the data argues for presumptive treatment of these sexually transmitted infections in all men testing positive for HIV without waiting for delayed test results. At least one audience member was skeptical that this practice would have any impact on subsequent transmission of HIV by the treated men.

Pathogenic Factors Affecting HIV-Specific Immune Responses
Monday, 10:00 a.m.
In the past two years it has become near dogma that within days of a new HIV infection in a body, there is massive and permanent destruction of CD4 cells and lymphoid tissue in the gut. Derek Shenefelt presented a study that found significant reconstitution of CD4 cells and lymphoid architecture in the gut after antiretroviral therapy and argued that previous studies that did not find this reconstitution had used the wrong method. But method is everything in science, and a parade of researchers took advantage of the Q&A period following his talk to raise doubts over the thoroughness of his group's methods.

Drivers of the HIV Epidemic and Potential Interventions
Monday, 4:00 p.m.
Frits Van Griensven reported on factors driving the worldwide HIV epidemic among men who have sex with men (MSM). In the United States in 2005, 67% of newly diagnosed men were MSM, and the proportion of cases among MSM has increased in the nation, even as those among heterosexuals and drug injectors have declined. In 2005, 42% of the diagnosed MSM were white and 36% were black. An analysis of multiple community-based studies produced an estimated annual incidence rate of 1.9% among MSM. There is evidence that the incidence rate among young black MSM may be twice as high, and historical data from the early epidemic in San Francisco suggests that HIV prevalence among African-American MSM may have always been higher than in whites.

In Latin America, estimated HIV prevalence among MSM ranges from 8% to 25%, far higher than in female sex workers, probably because there are few prevention efforts aimed at MSM in the region. A few recent studies have identified groups of MSM in African cities with HIV prevalence rates far higher than in the background population. In low-prevalence countries, with only modest rates of MSM activity, these groups could be contributing substantially to the overall epidemic. Similar patterns may be seen in Southeast Asia.

The factors that drive the epidemic among MSM have remained consistent for several decades: multiple partners, unprotected anal sex, drug use, sexually transmitted infections, and low socioeconomic status. Unfortunately, homophobia, discrimination, stigma, and poor access to effective prevention services have also been consistent realities for MSM at home and around the world.

Novel Approaches for Pharmacokinetic Assessment
Monday, 4:00 p.m.
Monica Gandhi walks you through the inherent difficulty of accurately measuring the measuring concentration of protease inhibitors in the blood. There is a lot of variation between individuals and within individuals hour by hour and day by day. But did you know that ARV drugs accumulate in the hair and that drug concentrations can be determined with only a dozen or so strands? Gandhi's group did a study that evaluated drug levels in the hair of 70 women taking a regimen containing Kaletra and in 154 women taking Reyataz. Remarkably, hair levels strongly predicted treatment success even when adherence was less than optimal. Interestingly, since drug levels remain in the hair as it grows at a rate of about one centimeter per month, it might be possible to trace a person's treatment history, including drug switches and lapses in adherence. I can't imagine why you would want to do that, but now you know.

Latest Concepts in HIV Drug Resistance
Monday, 4:00 p.m.
Jonathan Schapiro explains that the wide genetic variation of HIV found throughout the world can be thought of as a spectrum with boundaries imposed to create the divisions known as subtypes. Subtype C is associated with half the HIV infections worldwide.

Subtype B HIV represents about 10% of the HIV in the world, although because it was responsible for the AIDS epidemic in the United States and Europe, much more is known about Subtype B and its interactions with antiretroviral drugs. It is now becoming clear that different subtypes may have different frequencies of genetic mutations that are known as minor drug resistance mutations in Subtype B. Fortunately, no major drug resistance mutations have been associated with any particular subtype. One factor that complicates the study of drug resistance across multiple HIV subtypes is that the major genotypic, phenotypic, and replication capacity assays were designed with Subtype B in mind, since that's where the major market was. Fortunately, mounting clinical evidence from around the world suggests that antiretroviral drugs are generally very effective, no matter which HIV subtype is being suppressed.

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