Immune-function Analysis Of Pigs With Dumbing Immune Response To CSF Vaccine

Classical swine fever(CSF) is a highly contagious swine diease with high morbidity and mortality featuring symptoms of hemorrhagic fever and immune suppression.The diease is one of the most important animal zymoses that is notifiable ordered by OIE,usually leading to substantial economic losses to the pig industry.In recent years,the epidemiological features of CSF in our country have changed significantly,which brings new challenges to the control of CSF.CSF vaccine is.very important to the precaution of CSF.The large-scale outbreak of the disease has stopped in our country because of the comprehensive long-term vaccination of HCLV. But uninterrupted and distributed prevalence of the disease is ongoing. Although HCLV is the safe and effective CSF vaccine that is acknowledged worldwide,the pigs with dumbing immune response are common in many pig farms of our country,which has constitute a great threat to the pig industry.So it is necessary to study on the phenomenon and clarify its cause in order to improve the immune effect of CSF vaccine.It is helpful to eliminate the threat of the pig industry.In order to find out the pigs with dumbing immune response,782 sows' serum samples were detected by ELISA.As a result,72 samples were ascertained to be CSFV antibody-negative.Then the 72 samples were detected by neutralization test.In the end,38 CSFV antibody-negative pigs were found out.To clarify the causes of dumbing immune response,comprehensive survey was launched to the cooperative pig farm.According to the information from the survey,some of the common reasons were analysed one by one.Finally,the cytokines from PBL and the proportion of Th and Treg in PBL were to be examined in order to explore the causes of dumbing immune response to CSF vaccine more deeply. 15 pigs were picked out from 38 CSFV antibody-negative ones,which were from 6 different pigsties.At the same time,15 CSFV antibody-positive pigs were picked out as the control group from the same 6 pigsties.The anticoagulated blood and normal blood were collected from all the selected pigs.Serum isolated from the normal blood was detected again by ELISA and neutralization test.The result of the detection indicated that the 15 negative serums remained negative and the 15 positive ones also had no change.Then PBL were isolated from the anticoagulated blood of all 30 pigs.The concentration of IL-4,IL-5,IL-10 and IFN-γin the culture supernatant of PBL was detected by ELISA.The results told that the average concentration of IL-4 in the culture supernatant of 15 antibody-negative pigs' PBL was(63.2±6.21)pg/mL,which was much lower than(101.7±3.69) pg/mL--the one of 15 antibody-positive pigs'.The average concentration of IL-10 in the culture supernatant of 15 antibody-negative pigs' PBL was (159.3±8.58) pg/mL,which was much higher than(78.8±5.54)pg/mL--the one of 15 antibody-positive pigs'.The average concentration of IL-5 and IFN-γin the culture supernatant of experimental and control-group pigs' PBL had no conspicuous differences.Gene expression of the four cytokines above in antibody-negative and antibody-positive pigs' PBL was detected by Real-time PCR.The results accorded with the ones detected by ELISA.FCM was used to detected the percentage of Th and Treg in 30 pigs' PBL.The average percentage of Th in 15 CSFV antibody-negative pigs' PBL was(24.09±1.29)%,which was much lower than(37.49±1.60)%--the one of 15 CSFV antibody-positive pigs' The average percentage of Treg in 15 CSFV antibody-negative pigs' PBL was(2.34±0.20)%,which was much higher than (1.64±0.13)%--the one of 15 CSFV antibody-positive pigs'.All of the data above were analysed by statistical methods.In this study we demonstrated the differences of immune function between CSFV antibody-negative and CSFV antibody-positive pigs.The analysis of hese differences could help to offer some clues for exploring the causes of dumbing immune response to CSF vaccine.