Screening Of Immune Critical Protective Cytokines In Porcine Reproductive And Respiratory Syndrome

Porcine reproductive and respiratory syndrome(PRRS),also known as blue ear disease,is an acute,highly lethal infectious disease caused by PRRSV infection.Due to its unique ADE function,delayed production of neutralizing antibodies,persistent infection,and strong genetic variation,PRRS has not been effectively controlled,and it has brought huge economic losses to the pig industry.The PRRS vaccine stimulates the body's neutralizing antibodies to exert a certain degree of protective effect on PRRS immunity,but this protection is not complete,that is,the level of neutralizing antibodies is not the only standard to measure the body's ability to resist infection by PRRSV..Because cellular immunity predominates in anti-infectious immunity of PRRS,it is necessary to explore the protective effect of this virus after the immunization of pigs on the basis of PRRS cell immunity.To study various cytokines in anti-PRRSV immunization and screen out the key cytokine markers related to the production of immune antibodies.To evaluate the immune effect of PRRS vaccine,to reveal the pathogenic mechanism of PRRS,the immune response mechanism,to develop a reasonable immunization program,and to study The development of PRRSV vaccines,prevention,and elimination of PRRS are of great significance.This project was conducted to screen PRRSV antigen-negative,CSFV antigen-antibody-negative,PRV antigen-negative,and PCV-2 antigen-negative relative clean animals from a farm.Negative controls,experimental animal models,PRRSV immunization and experimental infection models were established.Forty piglets with similar body weight,well-growth,and gender identity were housed individually in a sterilized pig house.The feeds and tools used were all approved by IACUC,and the breeders had to be sterilized before entering or leaving the pig house.The 40 piglets were equally divided into 5 groups,namely,the non-free group,the low-free group,the medium-free group,the high-free group,and the viraemia group.Each group took the first 1,7,14 and 21 days of blood according to the experimental protocol.The ELISA was used for antibody detection and Real-time PCR and Western Blot were used to detect cytokines at the gene and protein levels,respectively.The results of ELISA showed that the S/P value was 0.35 in the non-exempt group,0.531 in the low-exempt group,1.494 in the medium-exempt group,and 2.163 in the high-exempt group,and the S/P group The P value is 3.165.The results indicated that in the experimental group,the non-exempt group,the low exempt group,the medium exempt group,and the high exempt group were established,and the infection group was established successfully.In addition,the levels of IFN-? and TGF-? in lymphocyte cytokines of piglets with different immune status and infection status were higher than those in other groups.The cytokines TGF-?,IL-8 and IFN-? had higher transcription levels than the other 10 cytokines in the same immune state and infection state,,and had significant differences compared with other cytokines.Western Blot results showed that IFN-? and TGF-? had higher expression levels.Overall,it was shown that lymphocyte cytokines IFN-? and TGF-? in piglets' blood are the cytokines responsible for the major immune protective effect when piglets infect RRRSV.