Nothing wakes me up on a rainy Monday morning like viral nomenclature!
So we have two kinds of HIV. HIV-1 we got from chimpanzees. HIV-2 we got from sooty mangabeys.
HIV-1 is further divided into Group M, N, and O, each resulting from a different zoonotic event from chimpanzees.
Several years ago, we identified SIV in wild gorillas. It groups with HIV-1 Group O.
Scientists have just published their findings from a patient they identified in 2004, who was infected with a ‘new’ kind of HIV. It clusters closer to SIVgorilla than anything else in a phylogenetic tree.
But instead of calling this ‘new’ variant HIV-3 (1 from chimpanzee, 2 from sooty mangabeys, 3 from gorilla), we are calling it HIV-1 Group P, because SIVgorilla groups with Group O, even though this patients sequences cluster closer to SIVgorilla than Group O clusters to SIVgorilla.
They identified this woman when her initial HIV test was positive, and a subsequent Western Blot yielded odd results– her antibodies kinda recognized envelope, but not gag. Okay… so they did PCR with several kits to see if they could find viral genomes in her blood. Group M specific PCR reagents couldnt see anything. A nonspecific Group O kit could. Like… a LOT of virus. 25,000 to 200,000 copies per ml. But shes still doing okay– CD4 T-cell count is fine.
Anyway, no point in freaking out over this ‘new’ HIV-1. Its just a different HIV-1, and we have lots of different HIV-1s. If allovasudden a ton of people start turning up with this ‘new’ HIV-1 and dying in a week, thats trouble. But this is just something different, and highlights the necessity of understanding the limitations of clinical tests, and the need to be on the lookout for viruses your tests cant see.