Who was patient zero that started the AIDS epidemic? For a long time, one person was considered the culprit of the infection, which covered all the inhabited continents of the planet - a homosexual, who had many promiscuous relationships. Researchers from Arizona State University and Cambridge University have struck a blow at this view.
Scientists have reconstructed the genome of the HIV strain, from which the epidemic of human immunodeficiency flared up in North America in the early 70s, and then around the world. It turned out that the epicenter of the spread of AIDS was New York, from where the virus began its triumphant march across the American continent. The scientists presented their findings in an article published in the journal Nature. They managed to determine how HIV entered the United States and what channels the virus found to spread to other territories.
New data confirmed the assumption that it was the Caribbean countries that became the gates through which the "plague of the 20th century" ended up in New York, from where it spread throughout the North American continent. In addition, the researchers reconstructed the genome of a virus that was in the blood of a person known as patient zero. It turned out that Gaetan Duga, an Air Canada flight attendant, was not at all the cause of the epidemic - the one who spread HIV across America.
New York for the virus was like dry grass for the fire. He managed to infect many people who belong to risk groups - drug addicts, gay barebackers (practicing unprotected anal sex), prostitutes and their clients, as well as all those who gravitate towards promiscuous sex. One of the branches of the infection stretched to Los Angeles, where doctors noticed a strange disease. The US Centers for Disease Control and Prevention (CDC) reported that five homosexual men were diagnosed with Pneumocystis pneumonia, a disease that predominantly affects immunocompromised people. It seemed strange to specialists that the patients turned out to be people with a similar lifestyle.
Although the patients were not familiar with each other, later studies have identified a suspect in the spread of AIDS (the disease received its name in 1982). It turned out to be Gaetan Duga, an Air Canada flight attendant. He had many homosexual partners. Malcolm Gladwell, author of Tipping Point: How Little Change Leads to Global Change, said there were about 2,500 across North America. Experts agreed that Duga was the center of the HIV network cluster.
Interestingly, the very term "patient zero" was erroneous, because in fact Dugas was "patient O". Specialists from the CDS have come up with a coding system to designate each of the patients. For example, in the sequence "LA 1, LA 2, NY 1, NY 2," the letters represent the cities in which the patients lived, and the numbers represent the order in which symptoms appeared. The O meant "Out (side) -of-California". However, "O" as a result of the encoding misunderstood by some researchers turned into "0".
HIV (yellow particles) infect a T cell
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Image: NIH / NIAID
The journalist Randy Shilts popularized the mistaken idea of Duga's involvement in the epidemic in his book And the Orchestra continued to play. However, HIV was found in the United States even before 1981, when AIDS was first described by the Centers for Disease Control and Prevention. Researchers Michael Worobey, who specializes in the evolution of the virus, and Richard McKay, an expert in public health history, have reconstructed the history of the latent epidemic by finding a way to reconstruct genetic samples that made analysis impossible with existing methods.
The hereditary information of HIV is contained in an RNA molecule with a length of 10 thousand nucleotides, which is very fragile and breaks with careless movement. Therefore, the scientist developed a technique called "RNA jackhammering" (English RNA jackhammering). RNA of the virus was isolated from blood serum and treated with enzymes that destroy DNA accidentally found in the sample. Then the ribonucleic acids were carefully broken into separate pieces, which were copied many times and converted into DNA using reverse transcriptase. After that, the whole genome was assembled from the fragments.
The spread of HIV in the United States
Image: Worobey et al./Nature
Scientists analyzed more than two thousand blood serum samples taken from men in the period 1978-1979. All of them deteriorated over time, but molecular biologists managed to restore eight almost complete genomes of the virus. Thus, the researchers obtained evidence that the epidemic was caused by various strains of HIV. The infection, which was originally located on the African continent, crossed the Atlantic Ocean and quickly spread throughout the Caribbean, and from there it reached New York.
It was established that the inhabitants of the metropolis began to become infected with the virus around 1970, from there HIV went to San Francisco and other cities in California, so that the culprit of the epidemic was not one person, but a great many, whose names do not matter. Randy Shilts's attempt to name Gaetan Dugas responsible for her can hardly be called justified from the point of view of both science and morality.
According to scientists, the results of the study will help to understand how various pathogens are spread in the human population. This will allow developing more effective strategies for preventing epidemics and eliminating dangerous infections.
Alexander Enikeev
