Mucosal and systemic immunity in mice after intranasal immunization with recombinant Lactococcus lactis expressing ORF6 of PRRSV

• The Nisin controlled expression (NICE) system of Lactococcus lactis was selected as vector.
• The M protein of PRRSV is provided with good immunogenicity in cellular immunity.
• The mucosal vaccine can induce mucosal immune, humoral and cellular immunity.

The purpose of the study was to construct mucosal vaccine of a recombinant Lactococcus lactis expressing PRRSV ORF6 gene and evaluate mucosal and systemic immune response against PRRSV in mice after intranasal immunization. The result show that the vaccine can stimulate mice to produce specific IgG in serum and remarkable special s-IgA in lung lavage fluid, at the same time, the contents of cytokines IL-2 and IFN-γ of the experimental group were significant higher than those of the control group (P < 0.01), however, the contents of cytokines IL-4 was not different to the all groups. In summary, the constructed mucosal vaccine can significantly induce mucosal immune, humoral immunity and cellular immunity involved Th1 type cytokines, which will lay a theoretical foundation on immune mechanism and new efficient vaccines for PRRSV.