To classify a new subtype, three cases must be discovered independently, according to guidelines issued in 2000.
Group M is the most prevalent form of the HIV-1 virus. Subtype L is now the 10th of this group and the first to be identified since the guidelines were issued.
Antiretroviral drugs, which today can reduce the viral load of an HIV carrier to the point at which the infection is both undetectable and cannot be transmitted further, have generally performed well against a variety of subtypes, according to research. But there is also some evidence of subtype differences in drug resistance.
"Since subtype L is part of the major group of HIV, Group M, I would expect current treatments to work with it," Mary Rodgers, a principal scientist and head of the Global Viral Surveillance Program at Abbott told AFP.