NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS BLOCK THE INCORPORATION OF VIRAL GLYCOPROTEINS INTO HIV-1 VIRIONS

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a key component of antiretroviral therapy that block reverse transcription in newly infected cells. NNRTIs have also been reported to induce premature activation of the HIV-1 protease in virus-producing cells, an activity that has been optimized in a class of NNRTIs known as targeted activators of cell kill (TACK). In this study, we used the TACK compound Pyr01 to investigate how NNRTI-induced premature protease activation affects virion composition and infectivity. We found that Pyr01 treatment markedly reduces the incorporation of the HIV-1 envelope (Env) glycoprotein into virus particles in an Env cytoplasmic tail-independent manner. Pyr01 treatment also disrupts the virion incorporation of foreign viral glycoproteins and causes a substantial loss of the viral enzymes from virions. Virions produced from NNRTI-treated cells exhibit reduced membrane order. The defect in viral glycoprotein incorporation requires an active protease, implicating premature protease-mediated disruption of the Gag lattice and resulting changes in membrane properties as the primary mechanism underlying these effects. These findings reveal that NNRTI-induced premature protease activation during virus assembly fundamentally changes the protein composition and membrane order of HIV-1 virions to markedly reduce particle infectivity. These results have implications for the use of TACK compounds therapeutically and provide basic insights into the properties of the viral membrane that promote viral glycoprotein incorporation.