Effects Of CPG ODN On Mice Immune Response As The Adjuvant Of Recombinant Lactococcus Lactis

Mucosal immunity plays a crucial role in defense against invading pathogens, the mucosal surfaces constitute the largest interface between the body and the external environment, including the respiratory, gastrointestinal and genital tracts. The Lactococcus lactis (L.1acti) have been studied emphatically as a vector of recombinant protein expression. The therapeutic proteins or protective antigen protein expressed can secrete and anchor in the cell envelope or bacterial peptidoglycans, thus, the L.1acti can presented the vaccine antigen to the mucosal surface and resulted in a specific s-IgA response and systemic immune response.To develop a mucosal vaccine which can stimulates not only a mucosal immune response but also the systemic immune response,we use the recombinant L.lacti PNZ8149/NZ3900-M/PRRS strain that expresses ORF6gene of PRRSV as antigen puls an adjuvant.Oligonucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, it can stimulates not only a rapid innate response but also the development of pathogen-specific adaptive immunity. Recently, it has been showed that CpG ODN is a promising mucosal adjuvant, but data on mucosal immune responses induced by CpG ODN plus the recombinant L.1actis are scarce. To evaluate the changes of immune response of recombinant L.lacti PNZ8149/NZ3900-M/PRRS strain that expresses ORF6gene of PRRSV and investigate the immune responses induced by intranasal immunization, with some doses of CpG ODN plus the recombinant L.1actis expressing ORF6gene of PRRSV antigen,the IgG in serum and s-IgA in lung lavage fluid and intestinal washes were analyzed by using a similar enzyme-linked immunosorbent assay (ELISA). In the same time we evaluated the changes about cytokines IL-2、IL-4、IL-5、and IFN-γ.The results clearly show that CpG ODN promoted the induction of IgG antibody in serum and s-IgA antibody in intestinal washes and lung lavage fluid. And the production of the s-IgA antibody in lung lavage fluid of immunized mice was higher than that in intestinal washes; the activity of cytokines IL-2and IFN-y in splenocytes on day14were investigated, in compared with the control group I, the activity of cytokines IL-2and IFN-y in CpG ODN plus recombinant L.1actis were increased, and higher significantly than that of the control groupIV (p<0.01). Results from this study indicate that stimulatory CpG ODN may be effective as a mucosal adjuvant with the recombinant L.1actis expressing ORF6gene of PRRSV antigen.Results indicated that mice immunized by the recombinant L.1actis expressing ORF6gene of PRRSV can significantly induce both mucosal immune responses and humoral immune responses against the PRRSV; CpG ODN could be an effective mucosal adjuvant with the recombinant L.1actis expressing ORF6gene of PRRSV antigen and induce Thl immunity response in vivo. The study is expected to lay a theoretical foundation on the adjuvant about recombinant strain vaccine.