The Highly Inducible Member of the 70 kDa Family of Heat Shock Proteins Increases Canine Distemper Virus Polymerase Activity

• Published in: Journal of general virology 1996-09, Vol.77 (9), p.2125-2135
• Main Authors: Oglesbee, Michael J, Liu, Zheng, Kenney, Hai, Brooks, Charles L
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - pharmacology; Animals; Cercopithecus aethiops; Distemper Virus, Canine - enzymology; DNA-Directed RNA Polymerases - metabolism; Dogs; HeLa Cells; HSP70 Heat-Shock Proteins - biosynthesis; HSP70 Heat-Shock Proteins - immunology; Humans; Nucleocapsid - metabolism; Vero Cells; Viral Proteins - metabolism
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-77-9-2125

Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, Ohio 43210, USA Author for correspondence: Michael J. Oglesbee. Fax + 1 614 292 6473, e-mail oglesbee.1 {at}osu.edu The cellular stress response is characterized by the production of heat shock proteins (HSP) which serve important cytoprotective functions. Paradoxically, in vitro induction of the stress response promotes cytopathic effect mediated by infection with canine distemper virus (CDV). The stress-mediated increase in cytopathic effect is correlated to the formation of complexes between the viral nucleocapsid (NC) and the major inducible member of the 70 kDa family of HSP (hsp72). The objective of the present study was to document the functional significance of CDV NC-HSP interaction. Cytoplasmic NC was purified from Vero cells lytically infected with the Onderstepoort strain of CDV. Both ultrastructural variants of CDV NC interacted with both hsp72 and the constitutively expressed member of the 70 kDa family of HSP (hsp73) in a reversible and ATP-dependent manner. An effect of hsp72/73 on NC polymerase activity was demonstrated using cell-free assays derived from either Vero or HeLa cell lines. Antibody specific to hsp72 suppressed both basal and stress-enhanced polymerase activity whereas hsp73-specific antibody had no affect. Supplementation of purified hsp72/73, but not hsp73 alone, enhanced basal polymerase activity in a dosage-dependent manner. Using purified NC variants, polymerase activity was demonstrated in pre-formed hsp72/73-NC complexes but not in NC devoid of HSP. These results suggest that the stimulatory effect of the stress response upon CDV gene expression may, in part, be mediated by a reversible and direct interaction between hsp72 and the viral core particle. Received 5 February 1996; accepted 4 June 1996.