Immunopotentiation effect of recombinant protein P60 and LLO of Listeria monocytogenes on the inactivated vaccine

To enhance immune efficacy of the inactivated Listeria monocytogenes(LM) vaccine,the invasion-associated protein p60 recombinant protein,low doses of LLO were added to the inactivated L.monocytogenes,with Montanide ISA206 as adjuvant.The inactivated L.monocytogenes vaccine was used as negative control and PBS as blank control.The serum antibodies,IL-4 and IFN-γ in rabbits were detected regularly after subcutaneous inoculation with the above vaccines.On day 21 after the second immunization,2×108 CFU of L.monocytogenes were injected into each rabbit by intraperitoneal injection.The pathological changes were observed and the growth of the L.Monocytogenes in vivo was detected every 24 h.Antibody level in rabbits injected with P60 and the LLO-additive vaccine was significantly higher compared with the other 2 groups,with induction of conversion from Th to Th1 and inhibition of conversion from Th to Th2,and the antigen-specific immune responses were regulated.The geometric growth rate(in blood and spleen) decreased from 64.69% to 24.06%,indicating that the immune effect of p60 and LLO-additive inactivited vaccine was significantly superior to others.The study showed that p60 and low dose of LLO could significantly enhance immune effect of inactivated L.Monocytogenes vaccine.