title: The pH independence of mammalian retrovirus infection.
abstract: The pH dependence of early steps in the infection of human and other cells by mammalian retroviruses and retroviral pseudotype particles of vesicular stomatitis virus (VSV) was investigated for 10 strains of retrovirus, including C-type and D-type oncoviruses and human lentiviruses. When cells were treated with weak bases (NH4Cl and amantadine) to raise the pH of endocytic vesicles, only ecotropic murine leukaemia virus (MLV-E) and VSV showed pH-dependent entry. Pretreatment of retrovirus stocks in media below pH 5.0 did not reduce their titres but inactivated VSV to less than 10(-8) of the initial titre. VSV (MLV-E) pseudotype infection in five out of six mouse and rat cell lines was inhibited by NH4Cl, indicating that infection proceeds via receptor-mediated endocytosis. In contrast, NH4Cl treatment has no effect on the infection of XC cells in which MLV-E induces syncytia. It is postulated that the pH-independent entry and cell fusion of XC cells by MLV-E may result from the activity of a cell surface proteinase that cleaves viral gp70 at neutral pH.
authors.affiliation: Chester Beatty Laboratories, Institute of Cancer Research, London, U.K.
authors.forename: M O
authors.initials: MO
authors.lastname: McClure
authors.forename: M A
authors.initials: MA
authors.lastname: Sommerfelt
authors.forename: M
authors.initials: M
authors.lastname: Marsh
authors.forename: R A
authors.initials: RA
authors.lastname: Weiss
mesh_terms: D000547:Amantadine / Q000494:pharmacology*; D000643:Ammonium Chloride / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D002461:Cell Line, Transformed; D003470:Culture Media; D004279:DNA, Viral / Q000096:biosynthesis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008985:Monensin / Q000494:pharmacology*; D012190:Retroviridae / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D014721:Vesicular stomatitis Indiana virus / Q000187:drug effects / Q000502:physiology*; D014764:Viral Proteins / Q000096:biosynthesis / Q000187:drug effects
chemical_list: D003470:Culture Media; D004279:DNA, Viral; D014764:Viral Proteins; D000643:Ammonium Chloride; D008985:Monensin; D000547:Amantadine