A tissue sample dating back to the 1960s harbors a near-complete sample of HIV, IFLScience reports, noting that this appears to be the oldest known nearly full-length sample of the virus.
The University of Arizona's Michael Worobey and his colleagues sifted through 1,645 formalin-fixed paraffin-embedded tissue specimens that were collected in Central Africa between 1958 and 1966. As they report in the Proceedings of the National Academy of Sciences, their RT-PCR assay detected HIV-1 within a sample that was collected in Kinshasa in 1966. LiveScience notes that while this is the oldest near-complete HIV genome, there are older, but less complete HIV genomes from 1959 and 1960.
Previously, scientists estimated that HIV arose in the early 1900s in Central Africa, and when Worobey and his colleagues added their new sample into a molecular clock analysis, it further confirmed that HIV likely emerged between 1881 and 1918.
"This is nice to know, because it means that our evolutionary models that we are always applying to our virus sequence work well," first author Sophie Gryseels from the Catholic University of Leuven tells LiveScience. "We didn't have big surprises."