Newsday - February 4, 1998
Laurie Garrett - Staff Correspondent

The finding, scientists said, not only dates the emergence of the AIDS virus, but genetically appears to be the mother strain, the ancestor of the most common forms of HIV-1 seen in the world today, including Type B, which dominates in the United States.

Though older claims of pre-epidemic HIV-positive blood samples have been made, none from before 1971 have held up to sophisticated laboratory scrutiny. A sample taken in 1971 from a Norwegian sailor contained a very rare form of HIV called Type O, not the form seen most regularly around the world.

The discovery was presented yesterday at the International Retrovirus Conference here by Dr. Toufo Zhu of the University of Washington in Seattle, a co-author on the paper along with Dr. David Ho of the Aaron Diamond AIDS Center in Manhattan.

The researchers said it could have two critical consequences: It suggests how and why the human immunodeficiency virus emerged, pointing experts to ways in which it might be possible to prevent future viral epidemics; and it suggests how rapidly HIV is evolving, giving a glimpse of what is yet to come.

Zhu said the finding suggests that all the HIV subtypes evolved from one introduction of HIV into people, rather than from many crossovers from animals to humans, as some have speculated. And given the steady rate at which HIV mutates, it also means the virus probably first got into people sometime in the 1940s or early '50s.

About 1 percent of the virus' genetic material changes each year. So the scientists compared the genes from the 39-year-old sample of HIV with those carried by current versions of HIV.

"We realized that if we had an old sequence" of HIV genes, "it would serve as a yardstick to measure the evolution of the current HIV," Ho said.

The 1959 strain was originally discovered in 1986 by Dr. Andre Nahmias of Emory University in Atlanta, along with 1,213 suspected HIV-positive blood samples drawn in Africa in the late 1950s and early 1960s.

He sent the samples to Dr. Max Essex of the Harvard School of Public Health who confirmed that this particular sample was HIV-positive, using then state-of-the-art technology.

But the Nahmias sample soon fell into disrepute amid allegations of errors and contaminations in the Essex lab. Nahmias then carefully stowed away the remainder of the tiny blood sample, drawn in 1959 from an unidentified male patient who died of a then-undiagnosable disease.

"I felt I would wait until the technology got better," Nahmias explained.

In 1994, Ho met Nahmias at a meeting and Nahmias agreed to supply him with half of his sample for analysis. Ho's lab then used its updated technologies to determine the sample's precise genetic code.

The question of just how HIV developed in humans has been controversial. For instance, Dutch virologist Jaap Goudsmit at the University of Amsterdam has argued against the contention that this finding supports the idea that the main body of HIV strains resulted from a single introduction into the African human population sometime before 1959.

Goudsmit says he believes there were at least two emergent events into the human population.

Meanwhile, Ho's analysis has been supported by both Bette Korber of the Los Alamos National Laboratory, who studied the sample's genetic sequence analysis with the lab's supercomputer; and viral ancestry expert Paul Sharp of the Department of Genetics at the University of Nottingham in England.

"From our paper we can't say what caused the [HIV] spread into the human population," Ho said. "We can only put a time on it - introduction in late 1940s, early 1950s which spread in the '60s."

The three scientists speculated, however, that widespread use of non-sterile syringes during mass vaccination campaigns may have been responsible.

But Dr. Peter Piot, the United Nations AIDS Program director, is skeptical. He points out that HIV remains a highly urbanized disease in most of Africa, not one that's evenly distributed. A vaccination program, he said, would probably result in a more widespread pattern.

The 1959 HIV ancestor - if accepted in the general scientific community - also offers a benchmark for timing the rate at which new strains of HIV have subsequently appeared.

HIV has mutated over the years to form 10 distinct subtypes, lettered A through J and an outlier, called O.

"I think we're still in a very dynamic stage of the epidemic because the virus is still evolving," Piot said. "Whether this means it will develop new modes of transmission, greater powers of [drug] resistance, we don't know."
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