Long after sex, the HIV virus sticks around and finds ways to replicate inside the body. Once an individual is infected with HIV, the virus’ DNA will reside in the body indefinitely. But some of the mechanisms behind HIV acquisition via male-to-female heterosexual contact are poorly understood. New findings, however, help unravel how HIV infects females, long after the act of heterosexual sex occurs.
A new study suggests that certain cells called vaginal epithelial dendritic cells “are potentially both infected early during heterosexual transmission and retain virus during treatment.” Version 1 of the study was published in The Journal of Clinical Investigation on May 3. CD4 or T cells aren’t present in the outermost regions of the female anatomy, which is why the team of investigators explored other methods of how HIV acquisition takes place.
Dr. Manish Sagar is the principal investigator of the study and is an infectious disease specialist at Boston Medical Center. Sagar and nine other investigators observed data from tissue samples and used a series of processes to separate the cells.
HIV is found in bodily fluids either as a free particle or inside other cells that have been infected such as CD4+/T cells, macrophages and dendritic cells. Investigators focused their findings specifically on vaginal epithelial dendritic cells.
“These cells are significant for two reasons,” Dr. Sagar told Plus. “First, HIV can replicate in these cells. Second, these cells are located in the outermost part of vagina. While HIV primarily replicates in T cells, T cells are not present in the outermost part of the vaginal mucosa, so they do not have direct exposure to an incoming virus. Thus, T cells are probably not the first cell infected during sexual exposure. Vaginal epithelial dendritic cells are most likely to encounter HIV when women are exposed to the virus during sexual contact. We think these are probably the first cells infected because of these two reasons.”
With so much focus always on T cells, it’s easy to overlook other the ways HIV can replicate.
Even with religious adherence to antiretrovirals, HIV finds places to hide within the body. “Our finding that HIV DNA is found in vaginal epithelial dendritic cells suggest that these cells are also one reason why HIV can persist forever even with effective treatment,” Sagar warned.
Researchers hope to build upon already-known aspects of the virus. “The basic cellular biology of male-to-female transmission is poorly understood,” Sagar said, but not HIV behavior in general. “Identifying the first infected cells opens new avenues into developing novel strategies to prevent HIV acquisition.”
Understanding the relationship between vaginal epithelial dendritic cells and HIV-1 is key to the possible introduction of other investigational medications. The team’s discoveries “may possibly lead to female specific prevention drug. Stopping infection of vaginal epithelial dendritic cells may prevent acquisition,” Sagar hopes.
Sagar’s team is also working on other projects which are not limited to the female sexual anatomy. They are also exploring how HIV acquisition takes place among men. “We are starting to explore if there are similar cells in foreskins,” Sagar said. “This is important because it has been well documented that circumcision reduces risk of HIV acquisition. We hypothesize that circumcision eliminates the epithelial dendritic cells and thus HIV transmission is lower.”
The recent findings surrounding HIV acquisition in the female body helps us understand how HIV DNA persists in the vaginal areas. It could lead, in theory, to female-specific approached to controlling the HIV virus.