Detection And Analysis Of Antibodies Against Peste Des Petits In Goats In Six Counties(Cities) Of Chuzhou City In 2018

Peste des petits ruminant(PPR)is a severe contact infectious disease caused by PPR virus,which causes the clinical symptoms such as purulent secretions in the eyes and nose,and oral erosion.For purpose of protection of the healthy development of sheep industry,China has implemented compulsory immunization measures against the disease.In April 2014,the PPR epidemic situation was discovered in Anhui Province.Due to the large amount of sheep breeding in Chuzhou,there were 110 professional cooperatives in Chuzhou for sheep raising up to 2018,accounting for 66%of the sheep farms.In order to understand the antibody level of Chuzhou goat PPR at the present stage,this study has collected the serum samples of goat farms in six counties(cities)of Chuzhou in both spring and autumn of 2018,as well as conducted the antibody detection and analysis.According to peste des petits ruminant virus(PPRV)N protein expression vector pET28a-PPRV N established by the laboratory,this experiment has transformed the recombinant plasmid pET28a-PPRV N into BL21 expression strain and purified the recombination protein.Using purified recombinant PPRV N protein as a coating antigen,180 clinical sheep serum samples were detected by optimized PPRV N protein indirect ELISA(PPRV N-ELISA)method and Kangbaide PPRV kit indirect ELISA method via the ELISA method established in the laboratory.The positive threshold of PPRV N-ELISA method was 0.389,with 136 positive samples and 44 negative samples detected.The positive rate was 75.6%;while 148 positive samples and 32 negative samples detected by Kangbaide PPRV kit and the positive rate was 82.2%.The positive coincidence rate was 91.89%,the negative coincidence rate was 90.63%and the total coincidence rate was 91.67%under the PPRV N-ELISA method in this trial,when compared to Kangbaide PPRV kit.The results showed that PPRV N-ELISA method could be used in clinical PPRV immune monitoring.PPRV N-ELISA method was used to detect 412 serum antibodies collected from Nanqiao District of Chuzhou,Lai'an County,Quanjiao County,Fengyang County,Mingguang City and Tianchang City of Anhui Province in 2018.Finally,a total of 313 positive serum samples and 99 negative serum samples were obtained,and the overall percentage of pass was 75.97%.The antibody yield was above 80%in Lai'an City,Quanjiao County and Tianchang City.The total antibody yield was 81.99%in spring and 65.87%in autumn.The antibody yield was 73.12%in breeding scale less than 300 heads of sheep farms;71.76%in breeding scale between 300 and 1000 heads of sheep farms and 80.82%in breeding scale more than 1,000 heads of sheep farms.In sheep under 150 days of age,the PPR antibody protection level was the highest,and the antibody yield was up to 85.57%.With the increase of age in days,the antibody protection level decreased to some extent but maintained at about 70%.The total antibody yield of the first immunized sheep was 74.37%,and the antibody protection level of the sheep immunized twice was more uniform.The antibody titer of sheep whose last immunization time less than 30 days was unstable,while the total antibody protection level of sheep whose last immunization time between 30-150 days was the highest.To sum up,this study has used PPRV N-ELISA method to monitor the serology of PPR antibody in six counties(cities)of Chuzhou in 2018.The prevalence of PRRV in Anhui Province is clear through the analysis of the results,which provides the data for the prevention and control of local PPRV.It laid a foundation for further immunization,prevention and control in Chuzhou area.