title: Inhibition or deficiency of cathepsin B leads defects in HIV-1 Gag pseudoparticle release in macrophages and HEK293T cells.
abstract: Human immunodeficiency virus type 1 (HIV-1) egresses from infected cells through utilizing the host membrane budding mechanisms. Assembly of HIV-1 Gag particles occurs on membranes where the Gag multimers subsequently bud off and form enveloped viral particles. In certain cell types such as macrophages, HIV-1 Gag particles have shown to be released into intracellular virus containing compartments (VCC) such as late endosomes, multivesicular bodies (MVBs) or invaginated plasma membrane pockets. Here, we showed that macrophages or HEK293T cells treated with the cathepsin B (CTSB)-specific inhibitor CA-074Me or cells deficient in CTSB failed to release HIV-1 Gag pseudoparticles into the extracellular environment. Based on immunofluorescence and electron microscopy, these cells retained the pseudoparticles in heterogeneous intracellular VCC. CA-074Me was also able to inhibit propagation of two enveloped viruses, herpes simplex virus and influenza A virus, but not non-enveloped enterovirus. These results suggest that CTSB is required for the efficient release of HIV-1 Gag pseudoparticles and targeting CTSB can be a new therapeutic strategy for inhibiting egress of HIV-1 and other enveloped viruses.
authors.affiliation: Department of Microbiology and Immunology and Centre for Human Immunology, Siebens-Drake Research Institute, University of Western Ontario, London, Ontario, Canada N6G 2V4.
authors.forename: Soon-Duck
authors.initials: SD
authors.lastname: Ha
authors.forename: Sangwook
authors.initials: S
authors.lastname: Park
authors.forename: Clayton James
authors.initials: CJ
authors.lastname: Hattlmann
authors.forename: Stephen Dominic
authors.initials: SD
authors.lastname: Barr
authors.forename: Sung Ouk
authors.initials: SO
authors.lastname: Kim
mesh_terms: D000818:Animals; D002401:Cathepsin B / Q000037:antagonists & inhibitors* / Q000172:deficiency*; D002460:Cell Line; D004151:Dipeptides / Q000494:pharmacology; D004770:Enterovirus / Q000187:drug effects; D057809:HEK293 Cells; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000821:virology*; D051379:Mice; D008810:Mice, Inbred C57BL; D021381:Protein Transport / Q000187:drug effects; D018139:Simplexvirus / Q000187:drug effects; D060149:Tetraspanin 30 / Q000378:metabolism; D014771:Virion / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D019065:Virus Assembly / Q000187:drug effects; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: C400541:CA 074 methyl ester; D004151:Dipeptides; D060149:Tetraspanin 30; D054301:gag Gene Products, Human Immunodeficiency Virus; D002401:Cathepsin B