Sexual networks and the transmission of drug-resistant HIV

Purpose of review We investigate the role that sexual networks may play in the dynamics of transmitted drug resistance (TDR) in human immunodeficiency virus (HIV) infection. Recent findings Studies examining individual correlates of TDR have generally failed to find strong predictors of TDR, with most only examining basic demographics and risk groups. Ecological studies that compare potential transmitters of drug resistance and the frequency of TDR in drug naive individuals have demonstrated that declines in TDR in some populations are mirrored by increasing efficacy of antiretroviral therapy and that the frequency of TDR is low given the number of potential transmitters; sexual networks may play a role in these phenomena. Phylogenetic approaches are becoming increasingly used to examine transmission networks of HIV but have yet to convincingly demonstrate clustering of sequences by drug resistance. Summary There are relatively few studies that suggest a role of sexual networks in the transmission of drug-resistant HIV. We believe that this is due to the difficulty in collecting sexual network data. Studies that integrate genotypic and behavioral data collection on recently HIV-infected individuals, potential transmitters, and their partners are needed in order to establish causal links between the structure of the sexual network and transmission of drug-resistant HIV.