HIV-1, the main strain of HIV carried by humans, was believed to have come from chimpanzees. But research published in Nature Medicine has uncovered a woman who carries a strain of HIV-1 that traces back to gorillas, Bloomberg reports.

A new strain of AIDS-causing HIV virus has been found in a 62-year-old woman from Cameroon. A study by French researchers in the academic journal Nature Medicine suggests that the new strain of HIV resembles that found in gorillas, a subtype of the simian immunodeficiency virus.

The known strains of HIV originated in chimpanzees. Scientists say gorilla-to-human transmission is the most likely reason for the emergence of the new strain. The spread of the new strain of HIV remains unknown, although scientists say the virus is well-adapted to replicate in human cells. The existing HIV anti-virals are still expected to be useful in treating the new HIV strain.

French doctors treating the 62-year-old Cameroonian woman who was living in Paris said they initially spotted some discrepancies in routine viral load tests.

Further analysis of the HIV strain she was infected with showed it was more closely related to SIV from gorillas than HIV from humans.

She is the only person known to be infected with the new strain but the researchers expect to find other cases.

The researchers reported their findings in the journal Nature Medicine and concluded: "The discovery of this novel HIV-1 lineage highlights the continuing need to watch closely for the emergence of new HIV variants."