Original HIV Infection Persists in the Body Months After Initial Infection

Researchers at the University of Rochester Medical Center, led by Ha Youn Lee, PhD, have discovered that the original HIV infection that first infects an individual is still present in the body months after initial exposure, despite thousands of changes that the virus undergoes to evade the body's immune system.

The researchers reached these conclusions by applying a mathematical model to data that was originally gathered by at team of the University of Wisconsin at Madison that studies how simian immunodeficiency virus (SIV) evolves. The University of Rochester team, who also published the study in the Journal of Virology, analyzed the genetic features of three key sections of the SIV genome as they evolved in the first few months after infection. Through ultradeep sequencing, the team found that CD8 T-lymphocytes, or cytotoxic T cells, cause the virus to degrade 400 times faster than they would if not in the presence of the CD8 cells.

In addition to this "selective pressure," the researchers discovered that SIV creates mutants in response to the CD8 cells at about the same rate that HIV does. But the researchers say that the most significant finding was that the original viral genetic sequences that cause the initial infection are still present in the body months later, "at a time that scientists call the 'viral set point,' which occurs about two to five months after infection," according to the researchers. They add that this finding is "a signal of just how difficult it is for the body to eradicate HIV from the body - key portions of the virus have managed to survive despite the immense immune assault."

According to Lee, the combination of the new technology of ultradeep sequencing and the discovery that the original infection persists in the body for such a long period of time may be key discoveries for new treatment options.

"The dynamics in the earliest stage of infection by HIV are incredibly complex, and understanding what happens is crucial for developing a vaccine," Lee said. "This new technology is very exciting. It allows us to look at the earliest stages of infection in more depth than we could otherwise, and to quantify exactly what is going on in the body. If we can understand it more completely, we can fine-tune vaccines under development."