Scientists at the NIH National Institute of Allergy and Infectious Diseases, USA, have come closer to explaining the genetic differences that can pick out some early-transmitting Human Immunodeficiency Viruses (HIVs) from those that are isolated later on – specifically, viruses found in the patient within the first four weeks after infection.
Experts say their findings could pave the way for new vaccines and prevention tools to block HIV during the early stages of sexual transmission, effectively preventing an infection from gaining a footing.
The genetic characteristics that they identified help HIV bind tightly to α4β7, a molecule, making some HIVs better at completing the many steps of sexual transmission, they become “founder” viruses that establish infection in a human.
The study also sheds light on CD4+ T cells, the primary immune cell targeted by HIV. The authors previously reported that gp120, an HIV surface protein, can bind to integrin α4β7 via a receptor that may be present on the surface of the CD4+ T-cell. α4β7 helps direct HIV-infected CD4+ T cells into the gut, where the virus can then begin to replicate quickly.
Given the new finding that certain early-transmitting isolates of HIV can have an affinity for α4β7, the scientists believe it is likely that CD4+ T cells with the α4β7 receptor play an important role in the sexual transmission of HIV.
Source: Laura Sivitz Leifman, NIH/National Institute of Allergy and Infectious Diseases