Scientists from four continents screened multiple tissue samples and uncovered the world’s second-oldest genetic sequence of HIV-1 group M, dating from 1960.
They then used the information to draw up an HIV-1 family tree for the viral strain, and estimated the age of each branch.
Calculations based on genetic mutation rates showed group M took root around the turn of the 20th century.
Results were backed by 48 year-old gene fragments from a wax-embedded lymph node tissue biopsy from a woman in Kinshasa in the Democratic Republic of Congo.
This was compared with the oldest known blood sample, taken in 1959 from a man from Kinshasa. Comparison of the two samples confirmed that the amount of genetic divergence between the two samples took more than 40 years to evolve.
Nature DOI: 10.1038/nature07390 (2008).