Plasma RNA viral load in HIV-1 group O infection by real-time PCR.

HIV-1 group O strains are highly divergent, and are found mainly in central Africa. The clinical course of group O infection is identical to that of HIV-1 group M infection, with rapid onset of immunodeficiency. The important divergence of the HIV-1 group O strains lead to high limitations of the commercial tests. We describe here a method based on real-time polymerase chain reaction (PCR) to quantify plasma HIV-1 group O RNA. Primers amplify both HIV-1 group O and HIV-1 group M strains. Conversely, the probe is HIV-1 group O-specific. The standard used to quantify the clinical samples is an RNA solution resulting from the transcription of a plasmid including the amplified fragment of PCR. Our technique is capable of amplifying a wide range of HIV-1 group O strains belonging to the three current clades. This technique can be used to monitor HIV-1 group O viral load, which has previously been difficult.