Effect And Application Of Different Vaccines On HP-PRRS

Porcine reproductive and respiratory syndrome(PRRS)is caused of porcine reproductive and respiratory syndrome virus(PRRSV)in the reproductive disorders of pregnancy and pig respiratory disease all age groups as the main characteristics of infectious diseases.Since PRRS was first reported in 1987,the disease has now been found in the world's major pig-rearing countries or regions,and the disease has caused immeasurable damage to the global pig industry.In April 2006,the outbreak of Highly pathogenic PRRS(HP-PRRS)caused an extremely severe blow to the development of the pig industry in China.To prevent and control the prevalence of HP-PRRSV,this study evaluated the immune protection effect of PRRSV attenuated vaccine against HP-PRRSV by immunomodulation experiment.Fifty piglets with negative PRRSV antibodies and antigens were divided into 5 groups.Four groups were immunized with PRRS attenuated virus vaccine from four different manufacturers as blank control,and then attacked with PRRSV mutant virulent strain JDJG P8.The immune effects of the four vaccines were evaluated according to the immune performance of the piglets and the clinical manifestations,antibody levels,viremia,and protective effects after challenge.The results showed that the immune response of piglets immunized with TJM was the least and the stress response of immunized JXA1 was greater;the four attenuated vaccines had better cross-protection against the attack of JG strain;the level of ELISA antibodies produced was lower than that of the JXA1-R and YN9 P90 immunization groups;the PRRSV ELISA antibody levels of the four groups immunized with the attenuated vaccines increased rapidly;the viremia of the TJM immunization group was similar to that of the blank group,although no disease,but long-term protection needs to be followed.The results of this experiment confirm that JXA1-R has a better immune effect and that the attenuated vaccine has better immune protection against the highly pathogenic PRRSV.This study was conducted to understand the changes in the antibodies of pigs before and after the PRRSV vaccine immunization.The 60 breeding pigs were selected for PRRSV attenuated vaccine immunization.PRRSV antibody testing was performed prior to immunization,and collected blood samples about one month after immunization to detected and analyzed PRRSV antibodies.The overall PRRSV-specific antibody values of all breeders showed an upward trend.To further evaluate the effectiveness of PRRSV attenuated vaccines in large-scale production and prevention and control of HP-PRRSV,this study used RT-PCR technology to monitor the prevalence of HP-PRRSV in an intensive pig farm in Hubei.The results of the analysis showed that pig farms were immunized four times a year with the highly pathogenic PRRSV attenuated vaccine(immunized once every 3 months),which can effectively reduce the clinical symptoms of PRRSV and reduce positive detection rate of HP-PRRSV.After immunization with the PRRS vaccine,breeding pigs had a certain decrease in their body condition,sensation and health,and there were differences between different vaccines.The immune JXA1-R attenuated vaccine had the greatest impact and the immune Boehringer and Tianjin strains had less impact.After the first infection of PRRSV in pigs,especially the PRRSV NADC30 strain,it will greatly affect the performance of the herd.Although the immunization of PRRS attenuated virus vaccine can effectively improve the overall antibody level of the herd,it will affect the body temperature,body weight and body condition,and health.Comprehensive measures can reduce the detoxification after immunization and the effects on the pigs,such as pre-and post-immunization biosafety measures,adding antibiotics before immunization or immunization,removing bacteria,adding Chinese herbal medicine after immunization,adding nutrients or probiotics to recuperate.Experiments confirmed that the PRRSV epidemic strains in Hubei Province in 2014-2015 were mainly HP-PRRSV and NADC30-Like strains;PRRSV JXA1-R had a better immune protection ability against HP-PRRSV;HP-PRRSV attenuated vaccines used on farms Immunization 4 times a year can effectively reduce the occurrence of PRRS clinical symptoms and HP-PRRSV positive detection rate in swine farms and service department pigs.This study has enriched China's PRRSV prevention and control technology,and in particular provided experimental and clinical data for the prevention and control of HP-PRRSV.