Since joining the UW faculty, he has collaborated with Drs. Connie Celum and Jared Baeten within the Department of Global Health International Clinical Research Center to conduct HIV-1 prevention clinical trials and observational studies in African heterosexual HIV-1 discordant couples. More recently, he has focused on conducting translational research studies to understand the pathogenesis of HIV-1 sexual transmission and particularly to identify host biological correlates for risk of HIV-1 infection. In this context he collaborates with numerous international researchers to apply genomics, proteomics and microbiome laboratory studies with state-of-the-art statistical analyses to identify factors that may be of particular relevance for public health interventions.