Inhibitors of HIV-1 maturation modulate conformational dynamics and heterogeneity of the immature Gag lattice

HIV-1 maturation requires the viral protease to cleave the Gag polyprotein into its constituent domains. Subsequent conformational and morphological changes result in a mature, infectious virion. Prior studies support a hypothesis in which Gag conformational dynamics and the heterogeneity of the immature Gag lattice enable proteolytic and morphological maturation. We developed a single-molecule Forster resonance energy transfer imaging approach to probe, in real time, the conformational dynamics of individual Gag molecules within immature HIV-1 virions. Our results capture Gag's conformational landscape and the spatial heterogeneity of the immature lattice. We evaluated inhibitors of maturation to identify immature lattice features that are modulated to disrupt maturation. Maturation inhibitors that act through diverse mechanisms, including lenacapavir and compounds that alter viral membrane composition, arrest Gag dynamics and reduce the spatial heterogeneity of the lattice. These observations support a model in which Gag dynamics and immature lattice organization regulate HIV-1 maturation.