An Envelope-determined Endocytic Route of Viral Entry Allows HIV-1 to Escape from Secreted Phospholipase A2 Entry Blockade

Secreted phospholipases A2 (sPLA2s) represent a new class of human immunodeficiency virus (HIV) inhibitors that block the early steps of virus entry into cells. Here, we applied an in vitro evolution/selection procedure to select, from primary HIV isolates, an emerging variant (HIVRBV-3) able to actively infect cells in the presence of sPLA2s. HIVRBV-3 represents a very atypical HIV-1 isolate because, in contrast to others, this virus requires a functional endocytic machinery to infect cells. Indeed, endocytosis inhibitors that affect endosome acidification (bafilomycin A1, monensin) and/or endosomal trafficking (nocodazole, latrunculin A) drastically reduced HIVRBV-3 replication. Using a standardized PCR-assay, we showed that endocytosis inhibitors block HIVRBV-3 entry just before the reverse transcription step. Concurrently, to identify the viral proteins responsible for the HIVRBV-3 atypical behaviour, we constructed a HIV-1 molecular chimera bearing different HIVRBV-3 proteins. We demonstrated that the sole presence of the HIVRBV-3 envelope glycoprotein is enough, not only to confer the resistance to sPLA2s, but also to direct HIVRBV-3 to the endosomal-dependant entry pathway. Interestingly, HIVRBV-3 envelope glycoprotein sequencing revealed an unusual structural pattern with the presence of rare mutations in the N-terminal region and V1–V2 envelope loop sequence extensions. Taken together, we conclude that HIV-1 may escape from entry inhibitors, such as sPLA2s, through the selection of a particular HIV-1 envelope glycoprotein that allows HIV to infect cells via an alternative entry route that relies on endosome trafficking.