Eipdemiological Study Of Procine Circovirus Type 2 Infection And Trituration, Application Of Inactived Vaccine In Anyang

Porcine Circovirus (PCV) is a small icosahedral nonenveloped virus with a single-stranded circular DNA genome, which belongs to the Circoviridae family.PCV1 was first discovered in 1974 by Tisher as noncytopathic contaminant of the porcine kidney cell culture PK-15(ATCC-CCL33).Its complete genome was composed of 1759 nucleotides. However, PCV2 has been associated with postweaning multisystemic wasting syndrome(PMWS),which genome consists of 1767 or 1768 nucleotides. PMWS is an immunosupressive disease characterized by progressive weight loss and multisystemic pathological lesion in the 6-8 week-old piglets.PCV2 was first identified in China in 2000,and since then, the distribution of PMWS has spread in all over country, caused significant economic losses and present a threat to the pig industry. So there has significance on strengthening epidemiological study and vaccine trituration. This study included as following:280 serum specimens were sampled from 6 different swine farms in Anyang for detecting the antibody against porcine circovirus type 2 by means of ELISA, the test result revealed that the positive detectable rate was irregular in the 6 swine farms, between 15.38% and 64.53%, the total positive detectable rate reached 43.21%, and confirmed PCV2 has been existing widely in swine farms in Anyang.The results also showed the positive rate for antibody against PCV2 was correlated with the pig age,in the same swine farm,the older it is,the higher the positive rate for antibody against PCV2 is.131 tissue samples,which were collected from pigs PCV2 infection from 6 counties in Anyang Region,were detectd for PCV2 by traditional PCR, the positive rate was up to 63.36%, the investigation indicated that this disease seemed to become epidemic in Anyang regions. Most of samples collected in September, October, Novermber during a year, and the positive rate was the most rate,71.43%,samples were overwhelmingly collected in this season.Based on the developmental stage,samples were overwhelming collected from 1 to 2 month old postweaning poglet,and the positive rate is the most high,is 74.62%,next is fatting pigs, the positive rate is 62.5%.By using PCR,20 piglets with PCV2 infection were detected from the tissues of heart,liver,spleen,lung,kidney,tonsil and inguinal lymph nodes respectively.The results showed the among the tested 20 pigs, PCV2 were detected in all tissues of the 6 pigs,and the results also showed the positive rates of tonsil and inguinal lymph nodes were all up to 100%,and spleen is 95% indicating that the three tissues were the optimal ones for PCV2 detection.The organs,such as spleen,lungs,kidney, lymph nodes were pooled, diluted,ground by homogenization, and centrifuged. The homogenate was disinfected and injected in postweaning piglets, to go with antibiotics simultaneously, The results showed that the inactived vaccine had much better protective and safer,and postweaning piglets infected the vaccine and antibiotics had more productive ability and less respiratory diseases than ones had no vaccine or had only antimicrobile.Immune Efficacy study of Inactivated Vaccine against PCV2, firstly rise and fall laws of antibody against PCV2 was studied by injected this vaccine, then conteracting toxic substances protection test and clinical application test were done. The result were showed rise and fall laws of antibody against PCV2 was consistent with dynamics laws of generating antiboby,during conteracting toxic substances protection test, after challenge the rectal temperatures of all piglets were recorded. Average temperature of piglets in challenge control group was higher than that of immunized piglets and no pyrexia was observed in mock piglets. The average weight was increased in immunized groups and mock group, but decreased in challenge control group.The fact that inactived vaccines could reduce the persistence time of PCV2 in piglets was indicated by detection of viremia and PCV2 in different tissues of challenged piglets. It could be concluded that inactivated PCV2 vaccines could induce immune respone in piglets and could protect piglets from PCV2 infection.