Researchers have found what they believe is the earliest case of HIV infection yet discovered. A sample taken in 1959 from a man living in what was then the Belgian Congo was shown to have been infected by an apparent ancestor of several subtypes of HIV (human immunodeficiency virus) now found around the world. The finding, by Dr David Ho and colleagues at the Aaron Diamond AIDS Research Centre in New York and published in the current issue of Nature, pushes back the previous earliest know case by over a decade.
The man was a Bantu living in Leopoldville, now Kinshasa in the Democratic Republic of Congo. A sample of the man's blood was kept in a serum bank.
Researchers from around the world are testing retained frozen serum samples in an effort to find early cases of HIV infection, the virus which causes AIDS. Early HIV versions could provide clues about the original source of the virus, according to a genetics researcher in Dublin.
The 1959 virus was studied and compared with current subgroups. The work suggested that the virus evolved from a single introduction into the African population not long before 1959. "This virus in the family tree sits pretty close to the centre and if we go and do statistics and genetics we realise that we could estimate the initial introduction to be in the time frame of 1940 to 1950," according to Dr Ho.
"It is really consistent with the picture that HIV was introduced to the human population in that time frame, probably from a monkey and then the virus evolved from there."
The fate of the 1959 victim was unknown. "There were no records . . . We don't even know if he was sick," Dr Ho said.
The finding refutes the suggestion that an early HIV version was responsible for AIDS-like syndromes noted in the 1930s in various European populations.
Scientists have yet to learn how HIV arose in humans. A similar viral illness in monkeys, simian immunodeficiency virus, has been known for many years. SIV could have crossed spontaneously to humans through a bite or close contact and then mutated or recombined to create a new pathogen, according to the Dublin researcher. Monkeys are also eaten as food and the transfer of viral material could have occurred in this way.
