Prevalence and circulation patterns of variant, atypical and resistant HIV in Los Angeles County (2007-2009).

The prevalence of transmitted HIV drug resistance (TDR) in Los Angeles County remains unknown, due in part to the absence of reliable genotypic data. The specific objectives of this study are to estimate the prevalence of TDR, to describe the demographic characteristics associated with TDR and to investigate the distribution of HIV-1 subtypes among persons newly diagnosed with HIV in Los Angeles County. From 2007 through 2009, 1,414 sequences were obtained from 7,100 persons newly diagnosed with HIV through HIV resistance surveillance. Overall, 257 (18%) sequences had some genetic evidence of drug resistance. Of these, 122 (9%) exhibited evidence of resistance to non-nucleoside reverse transcriptase inhibitors, 121 (9%) to nucleoside reverse transcriptase inhibitors and 76 (5%) to protease inhibitors. Subtype B was dominant (97%), followed by subtypes C (1.2%), CRF01_AE (0.8%), CRF02_AG (0.4%), A (0.3%), and F (0.1%). With a TDR prevalence of 18%, Los Angeles County ranks high compared with other jurisdictions across the nation. The prevalence of TDR in recent (19%) and long-standing (17%) HIV cases were similar, thus providing additional support for the notion that TDR-associated mutations may persist well beyond the period of recent infection. HIV-1 CRF01_AE, observed historically in central Africa and Asia, was observed to be circulating among men who have sex with men and heterosexuals in Los Angeles County. These findings underscore the need for continued and expanded HIV resistance surveillance to inform healthcare providers, policy makers and at-risk populations of emerging trends in HIV drug resistance.