Abstract

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-c 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.

2. Materials and methods

2.4. Cytokines detection
The evaluation of cellular immunity was performed by the detection of cytokines IL-2, IL-4, IL -5 and IFN-c. Six mice were killed at 37 days post the first inoculation. The mouse speen was remove aseptically. The splenocytes were isolated, counted, and diluted to the density of 1 106 cells/mL cell suspension. The evenly separated cells were aliquoted to 96-well plates according to the amount of 100 lL/well. 100 lL/well of complete 1640 medium with 2.5 lg/mL Con A as stimulus was added to each well. After incubation for 96, The supernatants were collected and the production of IL-2, IL-4, IL -5 and IFN-c were detected with the commercial ELISA Kit according to the manufacturer’s instruction (obtained from Wuhan Colorful Gene Biological Technology (Co., Ltd.)).