The variant, discovered in a New York City patient, may have raced from infection to full-blown AIDS in as little as four months, doctors said at the 12th Annual Retrovirus Conference. Typical strains can take 10 years to progress to full-blown AIDS.
Many new infections are resistant to treatment with common HIV drugs, and a small number of HIV variants have quickly progressed to the disease. But the New York patient's doctors said the case combines both characteristics in a worrisome way.
"The unique feature of this case is the convergence of ... the transmission of a remarkably drug-resistant HIV-1 variant and the extremely rapid clinical course to AIDS," the patient's doctors said in a review of his case.
The team is led by Dr. David Ho at Rockefeller University in New York.
Aspects of the HIV variant suggest it is especially deadly. It is capable of using both main entry points to infect cells, and it grows well in the lab, unlike most drug-resistant strains. It also causes cells that it infects to clump together, allowing them to kill other uninfected cells.
The patient, in his late 40s, was diagnosed in December and has lost 10 pounds in the past three weeks alone. It took him between four and 20 months to develop AIDS, Ho said.
Lab tests showed the patient was resistant to three of the four classes of AIDS drugs. He is taking other AIDS drugs now in the hope of vanquishing the infection.
Scientists are still trying to find the source of the man's disease. New York City health authorities have alerted doctors and begun to trace the patient's sexual contacts. The patient, whose name has been withheld, had unprotected anal sex with many other men, often in conjunction with methamphetamine use.
Some researchers have suggested that the patient may simply be unusually susceptible to AIDS, but his doctors said they have found no sign that his immune system is particularly vulnerable.
San Diego health officials have said they are studying a similar strain found there in a patient.
"We don't know whether this is a single isolated event or whether in fact there are other cases out there," said Ho, who is a paid consultant to ViroLogic Inc., which makes resistance tests.
Up to 950,000 people have the AIDS virus in the United States. About 18,000 die annually.
By Jeff Donn