Study On FMD And PPR Immune Antibody Monitoring And FMD Immunization Program Optimization Of Mutton Sheep In Jiangsu Province

Foot-and-mouth disease(FMD)and Peste des Petits Ruminants(PPR)are all a class of animal infectious diseases in China,which have the characteristics of high incidence,rapid transmission and wide range of epidemics.Once the epidemic breaks out,it will cause huge economic losses.For FMD and PPR prevention and control,comprehensive prevention and control measures based on vaccination were adopted.In order to understand the immunity and infection status of FMD and PPR in some large-scale mutton sheep farms in Jiangsu Province,In this study,FMD and PPR immunization antibodies were monitored for mutton sheep in some large-scale farms in Jiangsu Province,and the immunization program for foot-and-mouth disease of mutton sheep was optimized according to the law of antibody growth and decline.Real-time fluorescent RT-PCR and common PCR were used to detect the presence of foot-and-mouth disease virus(FMDV)and peste des petits ruminants virus(PPRV)in clinical samples,respectively,which provided the basis for comprehensive prevention and control of these two diseases in Jiangsu Province.1 Surveillance and analysis of immune antibodies to Foot-and-mouth disease and Peste des petits ruminants in Jiangsu ProvinceIn order to explore the vaccine immunization effect of large-scale sheep farms for foot-and-mouth disease and Peste des petits ruminants,this study monitored and analyzed the immune antibodies of foot-and-mouth disease type O and Peste des petits ruminants in some large-scale sheep farms in Jiangsu Province.The results show that:from 2017 to 2019,the pass rate of FMD immunization antibodies in Jiangsu mutton sheep was 70.85%,62.14%and 65.18%,and the pass rate of PPR immunization antibodies was 93.97%,77.18 and 77.78%,respectively.Among them,the pass rates of FMD immune antibodies in Yangzhou,Gaoyou and Haimen are all greater than 70%,and the pass rates of PPR immune antibodies in Yangzhou,Gaoyou,Haimen and Siyang are all greater than 70%.The pass rate of PPR immune antibodies is higher than that of FMD.2 Clinical detection of foot-and-mouth disease and Peste des petits ruminants virus in large-scale sheep farms in Jiangsu Province59 FMD immuno-antibody positive samples and 41 FMD immuno-antibody negative samples were taken for pathogenic detection by real-time fluorescent RT-PCR.The results showed that:25 samples(42.37%)of FMD immune antibody positive samples were positive for FMDV nucleic acid;21 samples(51.22%)were FMD virus nucleic acid positive for FMD immune antibody negative sample;This result suggests that mutton sheep infection with foot-and-mouth disease virus is very common.Positive humoral antibody cannot completely resist the infection of foot-and-mouth disease virus,but whether it is related to the virus load needs to be further tested.175 samples of PPR immune-antibody positive samples and 55 samples of PPR immune-antibody negative samples were taken for pathogenic detection by common PCR methods.The results found that 230 samples were positive or negative for PPR immune antibodies,and there was no PPRV.This result failed to reflect the relationship between PPR immune antibody levels and clinical infection,but at least shows the effectiveness of comprehensive prevention and control of PPR in Jiangsu Province.3 Optimization of immunization program for foot-and-mouth disease in large-scale sheep farms in Jiangsu ProvinceIn order to improve the effect of FMD immunization,an immunization program optimization experiment was carried out in a mutton sheep farm in Jiangsu Province.Four experimental groups of A(10),B(10),C(10),and D(10)were set in each field and FDM vaccination was conducted with different experimental procedures.Among them,group A is the 60-day-old first exemption+74-day-old second exemption,group B is the 60-day-old first exemption +81-day-old second exemption,group C is the 60-day first exemption+88-day-old second exemption,group D is 60-day-old first exemption.Collect samples regularly and detect the FMD immune antibody level of the flock by ELISA.The results showed that after the initial immunization of the mutton sheep in each group,the pass rate was all 70%in 3 weeks(81 days of age);After the second immunization of the three groups A,B,and C,the antibody level increased rapidly,and they were able to maintain a high number of qualified antibodies after 7 weeks of the first exemption.Group D was not immunized for the second time.Although the pass rate of antibodies could be maintained at more than 70%within a certain period of time,it was almost close to the critical value(70%)at the 7th week.In a word,the immune procedure of FMD in the large-scale sheep farms in Jiangsu Province was optimized through multiple experiments in four sheep farms:The first immunization was carried out at 60 days old,and the second immunization was carried out at 3-4 weeks after the first immunization.Under the same scheme,there was no significant difference between the sheep farms.