A 54-year-old human tissue sample was discovered to carry a strain of HIV, according to Live Science.
The sample was taken and preserved in 1966 from the Democratic Republic of Congo and its gene sequence, or genome, contained a mutation of HIV. The finding is now considered the oldest genome with an HIV strain — 10 years older than the most previous finding. HIV was not observed and studied by scientists until the early 1980s.
Researchers believe the disease known as HIV, which batters the immune system and progresses to AIDS if untreated, originated in humans in the early 20th century after infecting chimpanzees. Finding the 1966 genome helps scientists track how HIV mutated and turned into a disease that, so far, has killed over 32 million people.
American, Belgian, and DRC biologists have over 1,600 tissue specimens from the 1950s and 1960s. The scientists specifically sought HIV strains among the tissues but found it in only one biopsy sample, from a 38-year-old man. Older HIV strains than the 1966 finding have been uncovered, but "those pieces aren't as complete, and thus can't offer as much information about the virus' mutations," Live Science reports.
The findings were detailed in a recent edition of the Proceedings of the National Academy of Sciences for the United States of America.