A top U.S. health official says the first few minutes after HIV infection may be a window of opportunity to prevent the AIDS virus from firmly taking hold in the body.

The HIV that’s present during initial infection is different from the virus that replicates over time.  And that difference is very important.  So says Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health.

"The events that occur within literally minutes to hours from the time a person gets exposed actually determines what's going to happen for that person either getting infected or the nature of the disease and the opportunities to block those early events by either pre-exposure prophylaxis, microbicides or vaccines," he says.

One example of pre-exposure prophylaxis is the use of anti-retroviral drugs as a preventive measure. Currently, the drugs are most often administered after HIV infection is confirmed and the immune system is weakened. Microbicides are a gel, cream or suppository that releases a drug.

Evolution of HIV


Fauci says, "We're getting a very good feel that the virus that transmits to an individual is different a bit from the virus that ultimately evolves after months and years of replication."

He describes the virus initially transmitted as being "very restricted in its diversity...which interestingly, may make it even easier to block than we would have thought. Now having said that, we haven't been successful in blocking anything right now. But the nature of the virus is something that is very important."

Fauci will discuss the "brief window of opportunity and vulnerability" at this month's 18^th International AIDS Conference in Vienna.

"Once the virus establishes itself and truly begins to replicate, it establishes what we call a reservoir that is almost impossible, with the tools that we have now, to eradicate," he says.

Studying those early infections, Fauci says, could lead to insights for better prevention and treatment of HIV/AIDS and the development of a vaccine.

He says test results of a new microbicide will be released at the AIDS conference. Past microbicides have failed to block HIV, but this candidate releases antiretroviral drugs.

Dr. Fauci made his statements at a news conference Wednesday held at VOA