title: Cathepsin L and cathepsin B mediate reovirus disassembly in murine fibroblast cells.
abstract: After attachment to receptors, reovirus virions are internalized by endocytosis and exposed to acid-dependent proteases that catalyze viral disassembly. Previous studies using the cysteine protease inhibitor E64 and a mutant cell line that does not support reovirus disassembly suggest a requirement for specific endocytic proteases in reovirus entry. This study identifies the endocytic proteases that mediate reovirus disassembly in murine fibroblast cells. Infection of both L929 cells treated with the cathepsin L inhibitor Z-Phe-Tyr(t-Bu)-diazomethyl ketone and cathepsin L-deficient mouse embryo fibroblasts resulted in inefficient proteolytic disassembly of viral outer-capsid proteins and decreased viral yields. In contrast, both L929 cells treated with the cathepsin B inhibitor CA-074Me and cathepsin B-deficient mouse embryo fibroblasts support reovirus disassembly and growth. However, removal of both cathepsin B and cathepsin L activity completely abrogates disassembly and growth of reovirus. Concordantly, cathepsin L mediates reovirus disassembly more efficiently than cathepsin B in vitro. These results demonstrate that either cathepsin L or cathepsin B is required for reovirus entry into murine fibroblasts and indicate that cathepsin L is the primary mediator of reovirus disassembly. Moreover, these findings suggest that specific endocytic proteases can determine host cell susceptibility to infection by intracellular pathogens.
authors: Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors: Daniel H
authors: DH
authors: Ebert
authors: Jan
authors: J
authors: Deussing
authors: Christoph
authors: C
authors: Peters
authors: Terence S
authors: TS
authors: Dermody
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000187:drug effects / Q000235:genetics; D002401:Cathepsin B / Q000235:genetics / Q000378:metabolism*; D056668:Cathepsin L; D002403:Cathepsins / Q000235:genetics / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000821:virology; D017353:Gene Deletion; D007700:Kinetics; D007739:L Cells; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D030102:Orthoreovirus, Mammalian / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011487:Protein Conformation; D013379:Substrate Specificity; D010948:Viral Plaque Assay; D014771:Virion / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: C400541:CA 074 methyl ester; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L; C534278:Ctsl protein, mouse