Application of mouse model for evaluation of recombinant LpxC and GmhA as novel antigenic vaccine candidates of Glaesserella parasuis serotype 13

Glaesserella parasuis (G. parasuis) has been one of the bacteria affecting the large-scale swine industry. Lack of an effective vaccine has limited control of the disease, which has an effect on prevalence. In order to improve the cross-protection of vaccines, development on subunit vaccines has become a hot spot. In this study, we firstly cloned the lpxC and gmhA genes from G. parasuis serotype 13 isolates, and expressed and purified their proteins. The results showed that LpxC and GmhA can stimulate mice to produce IgG antibodies. Through testing the cytokine levels of interleukin 4 (IL-4), IL-10 and interferon-γ (IFN-γ), it is found that recombinant GmhA, the mixed LpxC and GmhA can stimulate the body to produce Th1 and Th2 immune responses, while recombinant LpxC and inactivated bacteria can only produce Th2 immune responses. On the protection rate for mice, recombinant LpxC, GmhA and the mixture of LpxC and GmhA can provide 50%, 50% and 60% protection for lethal dose of G. parasuis infection, respectively. The partial protection achieved by the recombinant LpxC and GmhA supports their potential as novel vaccine candidate antigens against G. parasuis.