The Effect Of PRRSV Peptides On The In Vitro Phenotype Of Lymphocytes From CSFV And PRRSV Vaccinated Piglets

Porcine reproductive and respiratory syndrome (PRRS) can lead to porcinereproductive and respiratory disorders. It spread rapidly when it was found in ourcountry in1996. Now PRRS has become one of the main diseases of pig farms in ourcountry. The reason why it is difficult for us to control PRRS is that the variation ofPRRSV, secondary infection of the PRRSV, mixed infection of PRRSV and otherviruses, particularly of mixed infection of PRRSV and CSFV. Therefore, it isimportant for us to research efficiently vaccine to prevent and control PRRS. Toclarify the mechanism of immune protection and the characteristic of cell phenotypein the process of PRRS Cell-mediated immunity is a prerequisite for us to solve theproblem.In order to detect the influence of PRRSV specific peptides on the cellphenotypes, we selected piglets from pig farm which hasn’t history of infected withPRRSV and CSFV. We tested the specific pathogen and antibody of peripheral bloodsamples and then discarded the samples which had CSFV, PRRSV, PRV or PCV2. Inconclusion, we selected20piglets to be used in our study. The piglets werevaccinated CSFV vaccine at the age of25weeks and vaccinated PRRSV vaccine afterCSFV immunization14d. We needed collect pig peripheral blood at the14th and28thday after PRRSV vaccine immunization. There were two kinds of Peripheral blood,which were blood with anticoagulant and blood without anticoagulant. We usedELISA technology to detect the samples of the expression of CSFV antibody andPRRSV antibody. According to the antibodies’ result, the test samples could bedivided into four groups. PBMC were cultured in5%CO2,37℃24h after the PBMCwere separated from blood with anticoagulant, and then stimulated Lymphocytes with PRRSV-GP5（GP5aa96-104VSTAGFVHG） and PRRSV-N （Naa106-114LPTHHTVRL）specific peptides24h. Different stages of CD3+, CD4+, CD8+Tlymphocyte phenotypic expression were tested by FCM.The piglet that produced effective CSFV antibody is60.00%of the wholepiglets and the ones that produced PRRSV antibody is65.00%at the28th day afterPRRSV vaccine immunization. Compared with the PRRSV infection group, in thegroup with effective PRRSV antibody the number of CD3+, CD4+and CD4+/CD8+increased, the number of CD8+reduced in infection group, which meant that thenumber of T lymphocyte increased, most of the lymphocyte differentiated into CD4+T lymphocyte, host has a higher level of ability to resist the virus. Rection ofphenotypes were various after using two PRRSV peptides to stimulate lymphocytes.When used PRRSV-GP5to stimulate and culture lymphocytes24h afterPRRSV vaccination14d, the number of CD3+increased and there was no significantdifference between the groups after peptide stimulation(P>0.05), the number of CD4+reduced and the number of it was significantly lower in negative-CSFV-negative-PRRSV antibody group than in negative-CSFV-positive-PRRSV antibody group(P<0.05),the number of CD8+increased and there was no significant differencebetween negative-CSFV-positive-PRRSV antibody groups(P>0.05), the ratio ofCD4+/CD8+reduced, the number of CD4+CD8+increased obviously, which meantthat PRRSV-GP5could promote T lymphocyte differentiation and enhance theimmune response. When used PRRSV-N to stimulate lymphocytes24h, the numberof CD3+increased but there was no significant difference between the groups, thenumber of CD4+increased and the number of it was significantly lower innegative-CSFV-negative-PRRSV antibody group than in positive-PRRSV antibodygroup(P<0.05),the number of CD8+were reduced, the ratio of CD4+/CD8+increasedand positive-CSFV-positive-PRRSV antibody group was significantly higher thanothers(P<0.05).When used PRRSV-GP5to stimulate and culture lymphocytes24h afterPRRSV vaccination28d, the number of CD3+in negative-CSFV-positive-PRRSV antibody group was significantly higher than it in positive-CSFV-positive-PRRSVantibody group(P<0.05), the number of CD4+was no significant difference betweenthe groups(P>0.05),the ratio of CD4+/CD8+in negative-CSFV-positive-PRRSVantibody group was significantly lower than other groups(P<0.05).When usedPRRSV-N to stimulate and culture lymphocytes24h, the number of CD3+was nosignificant difference between the groups(P>0.05), the number of CD4+innegative-CSFV-positive-PRRSV antibody group was significantly higher than it inpositive-CSFV-positive-PRRSV antibody group(P<0.05), the number of CD8+reduced, the ratio of CD4+/CD8+increased and it was significantly higher inpositive-CSFV-positive-PRRSV antibody group than others(P<0.05).The results indicate that a high level of CSFV immune can enhance thesuccessful of PRRSV vaccine. The immune of PRRS can increase the number of Tlymphocyte and body’s ability to resist the virus. PRRSV peptides stimulateLymphocytes24h after PRRSV vaccination14d, the number of CD3+and CD4+CD8+increased, CD4-CD8-reduced, which meant that PRRSV peptides can promotelymphocytes’ differentiation and proliferation. After PRRSV vaccination28d,PRRSV-N peptide can decrease the number of CD4-CD8-and increase the number ofCD4+CD8+, PRRSV-GP5peptide can increase the number of CD4+CD8+andCD4-CD8-, which meant that PRRSV peptides can promote lymphocytes’differentiation and proliferation and enhance lymphocyte immune function.PRRSV-GP5peptide can decrease the number of CD4+and increase the number ofCD8+, PRRSV-N peptide have opposite effect.