Competitive HIV budding suggests that a self-packaging gRNA:Gag-Pol complex directs HIV assembly and enforces infectivity.

To resolve the assembly mechanism of infectious HIV virions, we tested the ability of HIV to assemble infectious virions in the presence of a titrated mix of infectious/ non-infectious proviral genomes. The analysis of our assembly competitions shows that during translation, 15 {+/-} 5 Gag-Pols bind back to their parental gRNA creating a gRNA1: Gag-Pol15 complex. This complex initiates the infectious virion assembly through interactions mediated by cis packaged Gag/Gag-pols and the plasma membrane. Our analysis also shows the number of Gag-Pol and Env proteins packaged in an infectious HIV virion and the minimum functional units of these proteins required for viral infectivity. We suggest that aside from orchestrating the infectious virion assembly the gRNA1: Gag-Pol15 complex plays a major role in HIV evolution and likely hampers effectiveness of antiviral therapies. One-Sentence SummaryCompetitive HIV budding reveals gRNA1: Gag-Pol15 complex orchestrating viral assembly.