A single immunization with a rhabdovirus-based vector expressing severe acute respiratory syndrome coronavirus (SARS-CoV) S protein results in the production of high levels of SARS-CoV-neutralizing antibodies

Abstract

Foreign viral proteins expressed by rabies virus (RV) have been shown to induce potent humoral and cellular immune responses in immunized animals. In addition, highly attenuated and, therefore, very safe RV-based vectors have been constructed. Here, an RV-based vaccine vehicle was utilized as a novel vaccine against severe acute respiratory syndrome coronavirus (SARS-CoV). For this approach, the SARS-CoV nucleocapsid protein (N) or envelope spike protein (S) genes were cloned between the RV glycoprotein G and polymerase L genes. Recombinant vectors expressing SARS-CoV N or S protein were recovered and their immunogenicity was studied in mice. A single inoculation with the RV-based vaccine expressing SARS-CoV S protein induced a strong SARS-CoV-neutralizing antibody response. The ability of the RV-SARS-CoV S vector to confer immunity after a single inoculation makes this live vaccine a promising candidate for eradication of SARS-CoV in animal reservoirs, thereby reducing the risk of transmitting the infection to humans.

Fig. 1

Construction of recombinant RVs containing the SARS-CoV N gene (SN) and SARS-CoV S gene (SS).

Fig. 2

Immunofluorescence analysis of NA cells infected with SPBNGA (a), SPBNGA-SN (b) or SPBNGA-SS (c). Magnification ×20.

Fig. 3

(a) Western blot analysis of lysates from uninfected (control), SPBNGA-infected and SPBNGA-SN-infected BSR cells using a human SARS convalescence serum. (b) SDS-PAGE of immunoprecipitates prepared with a commercial anti-SARS-CoV S antibody and lysates of [³⁵S]methionine-labelled SPBNGA-infected or SPBNGA-SS-infected NA cells.

Fig. 4

SDS-PAGE of immunoprecipitates prepared with sera obtained from SPBNGA-SS-immunized mice and lysates of [³⁵S]methionine-labelled SPBNGA-infected or SPBNGA-SS-infected NA cells.