Prevalence and response to antiretroviral therapy of non-B subtypes of HIV in antiretroviral-naive individuals in British Columbia.

In North America, the B subtype of the major group (M) of HIV-1 predominates. Phylogenetic analysis of HIV reverse transcriptase and protease sequences isolated from 479 therapy-naive patients, first seeking treatment in British Columbia between June 1997 and August 1998, revealed a prevalence of 4.4% non-B virus. A range of different subtypes was identified, including one subtype A, 11 C, two D, five CRF01―AE, and one sample that could not be reliably subtyped. Baseline CD4 counts were significantly lower in individuals harbouring the non-B subtypes (P=0.02), but baseline viral loads were similar (P=0.80). In this study, individuals infected with non-B variants did not have a significantly different virological response to therapy after up to 18 months.