A discovery changes the date of the first HIV infection
though it was first isolated in the 1980s, it is generally accepted that the aids virus was rampant in the 1950s. A theory supports this premise: the disease spread when an experimental polio vaccine, cultured in primate cells, was tested on the people in Africa. There are other theories to explain the virus crossing over to humans. An evolutionary biologist has now claimed proof that the virus has been with us for more than a century--since much before the polio vaccine experiment.
The proof lay in 813 tissue samples from 1958-1962 in the archives of the Department of Anatomy and Pathology at the University of Kinshasa. Most of these samples had been treated and embedded in paraffin for microscopic studies. The chemical treatment preserved the samples. Among the sample was a lymph node biopsy taken in 1960 from a woman from Kinshasa, capital of the Democratic Republic of Congo.
The treatment process had broken down the genetic material. Michael Worobey, evolutionary biologist from the University of Arizona in Tucson, usa, led a group that sequenced these bits and pieces. The results showed the presence of the small bits of the hiv-1 genome. Using a database of hiv-1 sequences, the researchers figured out when the virus first surfaced.
Their results showed the most likely date for hiv's emergence was about 1908, when Kinshasa, earlier called Lopoldville, was emerging as a centre for trade under the colonial administration. Though an earlier study on a blood sample from a Kinshasa man, taken in 1959, had also put back the time of origin, the results were not conclusive.
The group will continue to study the samples. The team, with support from vaccine companies, is trying to develop a vaccine from ancestral viral sequences. The discovery has opened other options, too: reconstructing the ancient virus, and forecasting its future evolution using a computer model.
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