A small group of prostitutes in Africa each turn several tricks a day, never using condoms, but they have not become infected. John from Houston had receptive anal intercourse for several years with his HIV+ lover, no condoms. The lover has died of AIDS, but John shows no evidence of HIV. Two dozen people in a study have been seriously exposed to HIV but remain HIV-negative. Could these people be immune to HIV infection?
Several years ago if someone asked about immunity to the AIDS virus, medical researchers’ answer was “No!”, because immunity is generally dependent on those very body mechanisms which are wrecked by HIV. More recently, however, laboratory and epidemilogic evidence both suggest that indeed some people do have the ability to be exposed and remain HIV-free. The primary factors being examined currently are genetic ones.
Over a decade ago, science identified the protein molecule CD4 as the “docking site” on T-4 cells, onto which HIV attaches. But hooking on is one thing; getting inside is something else. Therefore, it was suspected there had to be something additional which enabled HIV entry into the T4 cell (also called CD4 cells).
Last year, Dr. Edward Berger identified another surface protein which in conjunction with CD4 permits the virus to fuse onto the T4 cell, enter, and infect the cell. He named it “fusin” and observed that it seemed to work in the later stages of infection. About the same time another protein, CCR5, was identified as performing a similar role in enabling viral entry, but it seemed to work earlier in the infection.
If a person’s body doesn’t make these proteins, they have a form of immunity, or at least have a better chance to fight off the infection. The trait, however, is not evenly spread through the human population. And no one knows whether they have the trait or not, so people shouldn’t drop their guard about risk behavior.
Next week, we’ll look at how we get this immunity and where it is found in the population.
— Sandy Bartlett
Community Education/Information Coordinator
ASA Info Line: 458-AIDS
This article appears in May 30 • 1997 and May 30 • 1997 (Cover).