Characteristics of patients recently infected with HIV-1 non-B subtypes in France: a nested study within the mandatory notification system for new HIV diagnoses.

The presence of HIV-1 non-B subtypes in Western Europe is commonly attributed to migration of individuals from non-European countries, but the possible role of domestic infections with non-B subtypes is not well investigated. The French mandatory anonymous reporting system for HIV is linked to a virological surveillance using assays for recent infection (<6 months) and serotyping. During the first semester of years 2007 to 2010, any sample corresponding to a non-B recent infection was analyzed by sequencing a 415-bp env region, followed by phylogenetic analysis and search for transmission clusters. Two hundred thirty-three recent HIV-1 infections with non-B variants were identified. They involved 5 subtypes and 7 circulating recombinant forms (CRFs). Ninety-two cases (39.5%) were due to heterosexual transmissions, of which 39 occurred in patients born in France. Eighty-five cases (36.5%) were identified in men having sex with men (MSM). Forty-three recent non-B infections (18.5%) segregated into 14 clusters, MSM being involved in 11 of them. Clustered transmission events included 2 to 7 cases per cluster. The largest cluster involved MSM infected by a CRF02_AG variant. In conclusion, we found that the spread of non-B subtypes in France occurs in individuals of French origin and that MSM are particularly involved in this dynamic.