| Porcine circovirus type 2 (PCV2) has been recognized as a primary pathogen of postweaning multisystemic wasting syndrome (PMWS) in young pigs. In this study, the changes of subpopulations of peripheral blood mononucleular cells (PBMC) and mRNA levels of cytokines in peripheral blood lymphocytes were systematically analyzed. Meanwhile, the influence of PCV2 infection on vaccination of classical swine fever vaccine (CSF-V) was investigated. The aim of this study was to elucidate effects of PCV2 infection on swine immune function from cellular and molecular levels.The linear regression equations of IL-2, IL-4, 1L-10, IL-12p40, IFN- y and TNF- a were established after construction of the standard competitive curves by quantitative competitive PCR (qc-PCR) between the competitive deleted plasmid and the larger plasmid with one pair of primers, respectively. The linear regrssion equations of ecch cytokine were derived with the related index (r2) of more than 0.95. The corresponding cytokine mRNA levels in the peripheral blood lymphocytes were analyzed by qcRT-PCR. The results showed that Th1 driven cytokines IL-2, IL-12p40 and IFN-γ mRNA levels of the infection group (n=3) were notably upregulated than that of the control group (n=2) after 14 days postinoculation (DPI), whereas Th2 driven cytokines IL-10 and IL-4 were waved statistically in this trial. IL-2 and IL-12p40 mRNA levels were notably increased in PCV2-infected pigs, and IFN- γ mRNA levels were upregulated statistically with exception of notable decrease at 7DPI (P<0.05). IL-4 mRNA levels of PCV2 infected pigs were statistically higher than that of the control pigs at 28DPI (P<0.01). Whereas IL-10 mRNA levels were significantly increased at 7DPI (P<0.01) and 14DPI (P<0.05) then clear decrease were detected at 35DPI (P<0.05). The results indicated that PCV2 infection could cause imbalance of Th1/Th1 driven immune response, resulting in the impairment of humoral immunity along with the enhancement of cellular immunity.The peripheral blood mononucleular cells (PBMC) subpopulations in PCV2-infected piglets were analyzed by triple labeling cytometry method and hemogram. The results showed that a notable loss of B lymphocyte counts of the infection group occurred at 28DPI (P<0.01) and 35DPI (P<0.05), and monocyte counts were statistically higher at 35DPI; the significant decrease of natural killer cell (NK) conts of the infection group was found at 21 DPI (P<0.01); the T lymphocyte counts of the infection group were notably upregulated at 21 and 42DPI. By triple labeling, the counts of subpopulations of T lymphocytes were observed, showing an obvious increase of Tc cells of the inocualted piglets at 21 CP<0.05) and 35DPI CP<0.05), a notable decrease at 10DPI (P<0.05), and a significant loss of of memory/activated T helper cells at 10DPI (P<0.05). However, naive Th cells were statistically increased at day 21 (P<0.01) and then notably declined at 28DPI (P<0.01). From our results, we canconclude that PCV2 infection is able to induce the impairment of humoral immunity, and to affect the specific cellular immunity in the early of infection, and to notably impair the unspecific cellular immunity in the middle of infection.Early weaned conventional piglets were randomly assigned to four groups. Group 1 (n=3) were vaccinated with CSF-V alone; group 2 (n=3) were inoculated with PCV2 (PCV2); group 3 (n=3) were inoculated with PCV2 and vaccinated with the vaccine two weeks later (when the viremia was detected) (PCV2/CSF-V); groups 4 (n=3) were simultaneously inoculated with both PCV2 and the vaccine (CSF-V/PCV2). The antibodies against CSF-V and PCV2 in sera from the treated piglets were detected by ELISA. In animals of group 2 and 3, the antibody response to CSF-V was significantly lower (P<0.05) than that of animals of group 1 at 52DPI. The average titers of antibodies against CSF-V in animals of group 1 were obviously higher than that of the group 3 and 4 inoculated with both PCV2 and the vaccine at 49 and 52DPI, respectively. The positive rate of antibodies against CSF-V in... |
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