For more than 30 years, U.S. scientists touted the idea that a French Canadian flight attendant known as “Patient 0” brought HIV to the country. But new evidence suggests the theory is wrong.
New genetic evidence revealed that Gaetan Dugas, who was widely blamed for the HIV/AIDS epidemic which has killed about 700,000 Americans, is innocent. The news, however, comes more than three decades after his death.
In a new paper, a group of researchers claims Dugas is not the first person with the infection in the U.S. The new theory suggests the Canadian patient was just one among many others that had the HIV virus in their system in the late ‘70s.
Researchers say they have evidence thousands of U.S. residents carried the virus during that period. And the genetic analysis also shows that the virus reached the U.S. through the Caribbean, not Canada. From the Caribbean, the infection spread to New York City in the early ‘70s and from there it dispersed across the country. But it needed about five years before it could depart from the Big Apple.
Lead author Michael Worobey said his team has no doubt on the “geographical direction of movement.”
Researchers came across new evidence after they sifted through a hepatitis B study among NYC and San Francisco gay men in the late ‘70s. The study’s participants agreed to donate serum for the research. After more than 30 years, scientists put the serum samples to new use.
The gay men weren’t screened for HIV as the disease was unknown back then. But if they did have the infection, the antibodies in their blood should reveal it. Study investigators analyzed the serum samples from New York City and learned 6.6 percent of volunteers had HIV antibodies in their blood. In San Francisco’s case, 3.7 percent of participants had the telltale proteins in their system.
Worobey explained that the presence of antibodies is a clear sign of the presence of a virus. But that’s about it. Antibodies cannot reveal more details on the virus. So, the research team had to dig even deeper.
They looked for pieces of HIV RNA in the samples. Scientists were aware that their endeavor was risky as the samples were decades-old. But they took their chances and analyzed 53 samples. In eight cases, the team was able to obtain the full HIV genome: three from SF and five from NYC.
“It took a mixture of patience and insanity, but these old sequences are as good as a time machine,”
the study’s lead author said.
Next, the research team tracked the virus’ evolution over time by considering the number of mutations in its genome. The same process had allowed other researchers estimate that a chimp in sub-Saharan Africa transmitted the infection to a human nearly 100 years ago.
Geneticists can tell how may mutations happen in the HIV genome within a specific time period. The number of mutations also revealed the virus reached the Caribbean in the late ‘60s. From there the strain jumped to New York City in 1970, or possibly a year later.
Researchers believe that from New York the infection spread to the West, Europe, Japan, Australia, and Latin America.
The findings appeared this week in the journal Nature.
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