Intranasal administration with recombinant Bacillus subtilis induces strong mucosal immune responses against pseudorabies

Abstract

BackgroundPseudorabies caused by pseudorabies virus (PRV) mainly infects the swine and seriously threatens the biosafety of the other animals, including humans. Since 2011, the outbreaks of PRV mutants have caused enormous economic losses in the swine industry, and traditional vaccines cannot offer enough protection. PRV can transmit by direct contact, aerosol transmission and pollutants. PRV mainly transmit through the nasal mucosa. After infecting the nasal epithelial cells, PRV can quickly infect the olfactory nerve and establish a potential infection of sensory neurons. Therefore, nasal immunity can effectively prevent viral colonization infection. Recombinant Bacillus subtilis has been widely used to deliver antigen and achieve adequate protective immune responses.ResultsThe present study successfully constructed recombinant Bacillus subtilis (B. subtilis) expressing the dominant antigen regions of PRV gC and gD proteins (named B. subtilis-gCa and B. subtilis-gDa). Furtherly, we evaluated the immunogenicity of the two recombinant B. subtilis in mice. The mice intranasal administration with B. subtilis-gCa and B. subtilis-gDa effectively stimulated IgA and IgG immune responses, further regulated specific T lymphocytes proliferative response by IFN-γ and IL-10, and ultimately produced high titers of neutralizing antibodies against PRV infection. In particular, B. subtilis-gDa possessed more excellent immune effect than B. subtilis-gCa in mice.ConclusionsThese results suggested that B. subtilis-gCa and B. subtilis-gDa could trigger high levels of mucosal and systemic immune responses and would be potential candidates for developing PRV vaccines.