HIV surveillance combining an assay for identification of very recent infection and phylogenetic analyses on dried spots.

BACKGROUND:Transmitted/founder viruses isolated at the early stage of infection are indicators of the variants that are spreading within a population. The French reporting system for new HIV diagnoses is linked to a virological surveillance using dried serum spots. METHODS:We combined an immunoassay for very recent infection (less than 31 days) to a phylogenetic analysis of transmitted/founder viruses and sociodemographic information to analyze the dynamics of the HIV-1 epidemic during a 3-year period. Bayesian coalescent-based methods were used to explore the temporal and spatial dynamics of the identified clusters. RESULTS:Of 17 010 dried serum spots collected, 549 very recent infections were identified for which both env sequences and sociodemographic data were available. Non-B transmitted/founder viruses were found in 196 cases (35.7%), belonging to six subtypes and seven circulating recombinant forms. Forty-three dyads/clusters were identified (range 2-11 cases), including 107 individuals (19.5%), mainly MSM. The largest cluster involved MSM infected by a CRF02_AG variant. Reconstruction of viral migrations across time suggests that Paris was the major hub of dissemination. CONCLUSION:The study shows the feasibility of the surveillance of the HIV epidemic using this methodology. The observation of actively growing spatiotemporal clusters allows identification of specific networks that may be targets for intervention.