Coverage of CROI 2008 (Conference on Retroviruses and Opportunistic Infections)

February 4–6, 2008, Boston, MA

 

Several studies reveal sobering information
on genital herpes and HIV

February 6, 2008

Several studies have shown that having the herpes simplex virus-2 (HSV-2), more commonly called genital herpes, increases the chance to get HIV by 2–3 times. HIV has a better chance of being passed when there’s a genital ulcer present, and HSV-2 is the most common sexually transmitted infection that causes genital ulcers, accounting for 3 out of 4 of these types of ulcers. Therefore, a good deal of research has assessed the relationship of HIV and HSV-2 on HIV transmission and disease progression. The study results below were presented at CROI 2008.

Study 1
The HPTN 039 study looked at whether controlling HSV-2 with the common drug, oral acyclovir, would reduce the sexual transmission of HIV. It followed more than 3,000 people—women in Africa and men who have sex with men (MSM) in North and South America. At the start of the study, all volunteers tested negative for HIV and 26% of women and 12% of MSM tested positive for genital herpes. They all reported high-risk sexual behavior. Each took either 400mg acyclovir twice a day or a placebo. Volunteers reported a high level of taking acyclovir as prescribed.

Unfortunately, this large study showed that taking acyclovir to control genital herpes did not lower the risk of HIV infection. A smaller study reported similar results last year. There were no significant differences between the groups based on sex, adherence or history of genital ulcers. However, in those taking acyclovir, the study did show a decrease in ulcers in one out of three people with a history of genital ulcer disease.
                                               
Study 2
A second small study reported findings on 20 women who were infected with both HIV and HSV-2, a common co-infection in HIV disease. This 18-week study assessed whether controlling HSV-2 lowers the blood and genital levels of HIV, which then would lower the chance of passing HIV onto others. The women took either 500mg valacyclovir (an anti-HSV drug) twice a day or a placebo. They had CD4 counts above 200 and were not taking HIV therapy.

For the women taking the drug, their HIV viral loads were found to be lower in both blood and genital samples. The differences were quite small, but large enough to be considered statistically significant.  Those on placebo showed a higher level of HIV in their blood and genital fluids. Therefore, controlling the levels of HSV-2 with anti-herpes drugs has the potential to lower the chance of passing HIV onto others and perhaps lower the rate of HIV disease progression. Other studies are currently examining these issues.

Study 3
A third study looked at how HIV and HSV-2 interact. The researchers infected human tissues with both viruses in the lab and examined the effects on each. The herpes virus was found to easily replicate in the tissue while HIV helped in that process. The researchers also found that HSV-2 impaired the production of the cell protein, CCR5, while another protein, CCXR4, was mildly affected.

HIV that uses R5 to enter cells is generally believed to be less aggressive than the HIV that uses X4. Therefore, these results show that having HSV-2 not only may aid in the transmission of HIV, it may actually help in the switch from R5 HIV to the more aggressive X4 HIV. These interactions may strongly affect the course of a person’s HIV disease.

Commentary
For people living with HIV, these results point to the importance of discussing all health issues with their health providers. These studies not only show how having HSV-2 can affect HIV prevention, they also show that having both viruses may affect the course of HIV disease progression. Since living with both viruses is common in people with HIV, how they interact and to what degree they affect HIV disease is a great concern.

At the least these sobering results may lead to other research, including ones of higher doses of acyclovir, new drugs or combinations of them. At best, they may lead to developing an effective herpes vaccine.