title: An envelope-determined endocytic route of viral entry allows HIV-1 to escape from secreted phospholipase A2 entry blockade.
abstract: Secreted phospholipases A(2) (sPLA(2)s) 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 (HIV(RBV-3)) able to actively infect cells in the presence of sPLA(2)s. HIV(RBV-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 A(1), monensin) and/or endosomal trafficking (nocodazole, latrunculin A) drastically reduced HIV(RBV-3) replication. Using a standardized PCR-assay, we showed that endocytosis inhibitors block HIV(RBV-3) entry just before the reverse transcription step. Concurrently, to identify the viral proteins responsible for the HIV(RBV-3) atypical behaviour, we constructed a HIV-1 molecular chimera bearing different HIV(RBV-3) proteins. We demonstrated that the sole presence of the HIV(RBV-3) envelope glycoprotein is enough, not only to confer the resistance to sPLA(2)s, but also to direct HIV(RBV-3) to the endosomal-dependent entry pathway. Interestingly, HIV(RBV-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.
authors.affiliation: Inserm U526, Laboratoire de Virologie, Faculté de Médecine, Avenue de Valombrose, 06107 Nice cedex 2, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Maurin
authors.forename: David
authors.initials: D
authors.lastname: Fenard
authors.forename: Gérard
authors.initials: G
authors.lastname: Lambeau
authors.forename: Alain
authors.initials: A
authors.lastname: Doglio
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D004705:Endocytosis / Q000187:drug effects; D014644:Genetic Variation; D015497:HIV-1 / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018942:Macrolides / Q000494:pharmacology; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D008985:Monensin / Q000494:pharmacology; D010741:Phospholipases A / Q000502:physiology*; D054467:Phospholipases A2; D017386:Sequence Homology, Amino Acid; D014759:Viral Envelope Proteins / Q000235:genetics / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects
chemical_list: D018942:Macrolides; D014759:Viral Envelope Proteins; C040929:bafilomycin A1; D008985:Monensin; D010741:Phospholipases A; D054467:Phospholipases A2