Detection Of Foot-and-mouth Virus By PCR And Monitoring And Analysis Of Foot-and-mouth Disease Vaccine Antibody

Foot-and-mouth disease(FMD)is an acute and febrile infectious disease that occurs in many kinds of cloven-hoofed animals.It has caused enormous economic losses to animal husbandry and aquaculture.Over the years,Yulin City has been suffering from foot and mouth disease of cattle,sheep and pigs,and under great pressure of epidemic prevention.At present,Suspecting FMD cases continue to occur in Yulin City,mainly because of the many virus subtypes,difficult to diagnose and poor vaccine control effect.In order to better prevent and control FMD,a rapid molecular diagnostic technique was used based on the FMDV subtypes in Yulin City,and the immune antibodies against FMDV type O,Asia I and A were detected and evaluated.It may provide practical and feasible reference for the prevention and control of FMD,and provide technical guidance for the prevention,control and purification of FMD.In this study,we try to use PCR detection technology by querying gene sequences,designing primers,synthetic primers,optimizing and testing PCR reaction conditions,PCR amplification and gel electrophoresis.A total of 526 serum samples were tested.We successfully amplified 553 bp band of FMDV type A from 8 sera positive which was detected positive by 3ABC.Because of the absence of positive pathogenic samples or standard strains,no positive results were found.A total of 1890 serum samples of pigs,cattle and sheep were collected from 48 scale farms and 120 scattered households,where compulsory immunization against FMD was carried out,in Yulin City,Shaanxi province.Immune antibodies against FMD were detected by liquid phase blocking ELISA.The results showed that the qualified rates of sheep O type,sheep Asia I type,swine O type,bovine O type,bovine Asia I type and bovine A type FMD antibody were 57.12±4.8% 、 64.66±4.2% 、 66.46±2.02% 、 56±5.98% 、 57.9±1.66% 、64.29±4.26%,respectively.In scale farms,only sheep Asia I and pig O FMD antibody qualified rate reached more than 70%,others were lower than 70%,while all FMD qualified rates of scattered households were below 70%.Antibody tests were conducted on 3 sheep farms,2 pig farms and 2 cattle farms.It was found that after 30 days of the first vaccination,the qualified rate of antibodies for the sheep O type,sheep Asia I type,pig O type,cow O type,bovine Asia I type and bovine A type FMD antibody were all lower than 70%.The second immunization was conducted one month after the first immunization,and the antibody was tested 30 days later.The qualified rate of antibodies for the sheep O type,sheep Asia I type,swine O type,bovine O type,bovine Asia I and bovine A reached more than80%.The results showed that in order to achieve ideal immune protection effect,the second intensive immunization should be carried out one month after the first immunization.In summary,this study initially understood and mastered the immunization effect of foot-and-mouth disease vaccine in Yulin City and give forward reasonable suggestions for prevention and control of foot-and-mouth disease.