Mouse hepatitis virus spike and nucleocapsid proteins expressed by adenovirus vectors protect mice against a lethal infection

Abstract

Infection with the mouse hepatitis coronavirus (MHV) provides an excellent model for the study of viral diseases of the central nervous system and the gastrointestinal tract. With the ultimate aim of studying mucosal immunity to MHV we have cloned the genes encoding the structural proteins of MHV strain A59 (MHV-A59) into the E3 region of a human adenovirus type 5 vector. Infection of HeLa cells with the resulting recombinant adenoviruses AdMHVS, AdMHVN and AdMHVM revealed the correct expression of the spike (S), nucleocapsid (N) and membrane (M) proteins, respectively. Intraperitoneal inoculation of BALB/c mice with the recombinant viruses elicited serum antibodies which specifically recognized the respective MHV proteins in an immunoprecipitation assay. Only antibodies to the S protein neutralized MHV-A59 in vitro but titres were low. When analysed by ELISA or by immunofluorescence only the antibody response to the N protein was significant; weak responses or no detectable response at all were found for S and M, respectively. Upon intracerebral challenge with a lethal dose of MHV-A59 we found that a significant fraction of animals vaccinated with adenovirus vectors expressing either the S protein or N protein were protected. This protective effect was significantly stronger when the animals were given a booster immunization with the same vector prior to challenge. No protection was induced by AdMHVM. Interestingly, enhanced protection resulted when AdMHVS and AdMHVN were applied in combination as compared to survival after single immunizations. The results indicate that both the N and S proteins generate a protective immune response and suggest that this response is enhanced by combined expression of the two proteins.

Identification of Immunodominant Sites on the Spike Protein of Severe Acute Respiratory Syndrome (SARS) Coronavirus: Implication for Developing SARS Diagnostics and Vaccines

“…In the case of murine hepatitis virus, its immunodominant sites responsible for eliciting protective humoral responses are mainly located in the S protein S1 domain (21,22). The S protein of transmissible gastroenteritis virus contains four major antigenic sites (A to D), and site A on the S1 subunit is the main inducer of neutralizing Abs (23)(24)(25).…”

Severe acute respiratory syndrome vaccine efficacy in ferrets: whole killed virus and adenovirus-vectored vaccines

“…Studies from other animal CoV vaccines have shown that the CoV nucleocapsid (N) protein may represent another antigen candidate for vaccine development (Anton et al, 1996;Olsen, 1993). Although antibodies to CoV N proteins have no virus-neutralizing activity, there is evidence that the protein may provide protection in vivo by induction of cell-mediated immunity, although it has also been suggested to induce eosinophilic infiltrates resulting in immunopathology (Deming et al, 2006;Enjuanes et al, 1995;Stohlman et al, 1995;Wesseling et al, 1993). N protein has been shown to generate CoV-specific CD8 + T cells (Boots et al, 1991;Seo et al, 1997;Stohlman et al, 1993Stohlman et al, , 1995; it also provides protection in animals in response to infection by animal CoV (Collisson et al, 2000;Seo et al, 1997).…”

An adenovirus recombinant expressing the spike glycoprotein of porcine respiratory coronavirus is immunogenic in swine

“…A live recombinant Ad5 vector has been demonstrated to be an effective rabies vaccine when administered to skunks and foxes by the oral route (Charlton et al, 1992). Ad5 has been used successfully for expression of the S protein of the coronavirus mouse hepatitis virus (Wesseling et al, 1993).…”