Induction of Caspase Activation and Cleavage of the Viral Nucleocapsid Protein in Different Cell Types during Crimean-Congo Hemorrhagic Fever Virus Infection

• Published in: The Journal of biological chemistry Vol. 286; no. 5; pp. 3227 - 3234
• Main Authors: Karlberg, Helen, Tan, Yee-Joo, Mirazimi, Ali
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.02.2011; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Apoptosis; Caspase; Caspase 3 - metabolism; Caspase inhibitors; Caspase-3; CCHFV; Cell Line; Cell Line, Tumor; Cell survival; Chlorocebus aethiops; Conserved sequence; Crimean-Congo Hemorrhagic Fever Virus; Data processing; Defense mechanisms; Enzyme Activation; Hemorrhagic fever; Hemorrhagic Fever Virus, Crimean-Congo - pathogenicity; Hemorrhagic Fever, Crimean - immunology; Hemorrhagic Fever, Crimean - pathology; Host-Pathogen Interactions - immunology; Humans; Hydrolysis; Infection; Microbiology; Negative-strand RNA Viruses; Nucleocapsid Protein; Nucleocapsid Proteins - metabolism; Nucleocapsids; Pathogens; Peptide Hydrolases; Progeny; Protein Assembly; Proteolysis; Replication; RNA; Site-directed mutagenesis; Vero Cells; Viral Replication; Viral Replication; Negative-strand RNA Viruses; CCHFV; Nucleocapsid Protein; Caspase; Crimean-Congo Hemorrhagic Fever Virus; Apoptosis; Protein Assembly
• DOI: 10.1074/jbc.M110.149369
• ISSN: 0021-9258; 1083-351X

Regulation of apoptosis during infection has been observed for several viral pathogens. Programmed cell death and regulation of apoptosis in response to a viral infection are important factors for host or virus survival. It is not known whether Crimean-Congo hemorrhagic fever virus (CCHFV) infection regulates the apoptosis process in vitro. This study for the first time suggests that CCHFV induces apoptosis, which may be dependent on caspase-3 activation. This study also shows that the coding sequence of the S segment of CCHFV contains a proteolytic cleavage site, DEVD, which is conserved in all CCHFV strains. By using different recombinant expression systems and site-directed mutagenesis, we demonstrated that this motif is subject to caspase cleavage. We also demonstrate that CCHFV nucleocapsid protein (NP) is cleaved into a 30-kDa fragment at the same time as caspase activity is induced during infection. Using caspase inhibitors and cells lacking caspase-3, we clearly demonstrate that the cleavage of NP is caspase-3-dependent. We also show that the inhibition of apoptosis induced progeny viral titers of ∼80–90%. Thus, caspase-3-dependent cleavage of NP may represent a host defense mechanism against lytic CCHFV infection. Taken together, these data suggest that the most abundant protein of CCHFV, which has several essential functions such as protection of viral RNA and participation in various processes in the replication cycle, can be subjected to cleavage by host cell caspases.