乳酸菌NICE（乳链菌肽控制表达nisin controlled expression，NICE）系统可将治疗性蛋白或保护性抗原蛋白表达于细胞外或锚定于菌体的肽聚糖上，递呈抗原蛋白并激活粘膜免疫系统，刺激特异性s-IgA的产生使其作为粘膜免疫原递呈的活载体成为可能。本试验将构建的重组乳酸乳球菌PNZ8149/NZ3900-M/PRRS鼻腔免疫BALB/c小鼠，检测呼吸道粘膜中抗体s-IgA和血清中特异性抗体IgG含量，评价其动态变化情况，同时检测脾脏细胞因子IL-4和IL-10的活性。结果重组乳酸乳球菌PNZ8149/NZ3900-M/PRRS免疫小鼠后，在测定时间内重组菌试验组小鼠呼吸道粘膜中特异性s-IgA水平高于对照组，差异极显著（(P<0.01)；血清中特异性抗体IgG水显著高于对照组（(P<0.01)；脾脏细胞悬液中的IL-10和IL-4含量与对照组无差异性（p>0.05），结果表明重组菌PNZ8149/NZ3900-M/PRRS经粘膜途径免疫小鼠后能能刺激小鼠粘膜特异性抗体s-IgA和血清中特异性抗体IgG的分泌，且能避免粘膜免疫耐受的产生，为该重组疫苗的进一步应用奠定了理论基础。

The food-grade Nisin controlled expression (NICE) system of Lactococcus lactis (L.lacti) was 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 and thus the NICE system of L.lacti can present the vaccine antigen to the mucosal surface and result in a specific s-IgA response. Using recombinant L.lacti that present antigens as live mucosal vaccines provides an effective way to prevent microorganisms invading and shows a promising future. In this study, BALB/c mice were immunized with the bacterial supernatant to evaluate the mucosal immune response and Immune tolerance of recombinant L.1acti PNZ8149/NZ3900-M/PRRS strain that expresses ORF6 gene of PRRSV,. IgG in serum and s-IgA in lung lavage fluid and intestinal washes were analyzed by using a similar enzyme-linked immunosorbent assay (ELISA). For evaluating changes in cytokines IL-4 and IL-10, the spleen collected was analyzed. The results clearly showed that mice immunized with recombinant strain PNZ8149/NZ3900-M/PRRS could induce remarkable special s-IgA in lung lavage fluid, at the whole experimental session, compared with the control group I and II. The level of special s-IgA and IgG showed significantly increase(P<0.01) and IL-4 and IL-10 contents of cytokines showed little difference to those of the control groups. All the results indicated that mice immunized by the recombinant L.lactis expressing ORF6 gene of PRRSV can significantly induce mucosal immune responses and avoid producing the phenomenon of mucosal immune tolerance.The study was expected to lay a theoretical foundation on developing of the gene engineering L.1acti s mucosal vaccines.