Weak Strain of AIDS Virus Gives Hope That Live Vaccine May Work

An Australian with the AIDS virus who unknowingly infected that country’s blood supply 14 years ago has given scientists stronger evidence that a live AIDS vaccine might work.

The blood donor and six people infected by his plasma have remained healthy longer than a decade and even have normal immune systems because they have a genetically weak strain of the AIDS virus, Australian scientists report in today’s edition of the journal Science.

Coincidentally, the HIV infecting the Australians is almost identical to a man-made strain U.S. researchers have developed as a possible AIDS vaccine--one many scientists fear could be deadly even though weakened. Until now, only one other person in the world had been found living with weak HIV.

“The Australians provide additional information that these kinds of strains can be safe over the long run,” said Dr. Ronald Desrosiers of the New England Primate Research Center. He developed the potential vaccine.

Dr. Anthony S. Fauci, chief of the National Institute of Allergy and Infectious Diseases, said: “This extraordinary experiment of nature . . . makes you think again about the feasibility of a live attenuated vaccine.

“But it doesn’t necessarily take us any closer to having an attenuated live vaccine,” he warned.

The findings help explain why some people maintain healthy immune systems beyond the 10 years it typically takes HIV to turn deadly, wrote study author Nicholas Deacon of the Macfarlane Burnet Centre for Medical Research.

The Australians’ HIV is missing parts of a gene called nef. Scientists believe nef spurs HIV to reproduce frantically until it overwhelms patients’ immune systems--and if nef doesn’t work right, immune cells can control HIV just as they fight most viruses.