The Title Of Thesis Porcine Circovirus Virus Type 2 Serological Survey And The Analysis Of Genetic Mutation In West Fujian

Porcine circovirus virus disease (porcine circovirus type 2 diseases, PCVD)Which is caused by porcine circovirus virus type 2, or a variety of the symptoms associated with it, so it is also known as porcine circovirus virus associated diseases (PCVAD). Abdominal breathing, diarrhea, interstitial pneumonia, anemia, and progressive emaciation and significant lymphadenopathy are the main clinical signs in weaning piglets. PCVAD is an immunity suppressive disease, widely spread in the world and cost of economic to the pig industry.in order to understand the seology and molecular epidemiology characteristic in West Fujian and Aren,1771 swine serum samples and 10 tissue samples from suspected were Pig from 2013 to 2015. ELISA, PCR, gene sequencing, and phylogenetic tree analysis methods were used to understand seology and molecular epidemiology, of porcine circovirus virus type 2 (PCV-2) the results showed:1. Serum samples were 93.0% PCR positive, including 99.8% in breeding pigs, the positive rates in lactation piglets, weanned pigs and early fattening pigs decrease gradually, Which was 91.6%,80.4% and 78.1% respectively,but increased to 100% in late fattening. In vaccinated group, the positive rates in breeding pigs, lactation piglets, weanned pigs, early fattening and late fattening were 100.0%,92.4%,78.9%,71.3%, 78.9% respectively. The average vaccination blocking value in breeding pigs was of 1.89, slightly higher than that of lactation piglet1.42. The value in both weanned pig and early fattening the pig was significantly lower than breeding herd, which was 0.99 and 0.86 respectively.The positive rate and blocking value in late fattening rise again. In nonvaccinated group, the positive rates in breeding pigs, lactation piglets, weanned pigs, early fattening and late fattening was 99.5%,90.3%,85.4%,90.3%,100.0% respectively, the average block value was 1.60,1.29,0.85,1.33,1.56.2. Sequencing analysis showed that 10 strains of PCV-2 were 1766-1768 bp in genome, with 94.6%-99.7% homology compare to most domestic strains and 94%-99.2% to international reference strains.3. Phylogenetic tree result showed that the 10 strains of PCV-2 strains could be divided into three groups, belong to the PCV-2 a,1 strain 9 strains belong to PCV-2 b (2 to 1 a/AB,7 strains of 1 c).Conclusion the results showed that total positive rate of PCV-2 in large-scale pig farms was high. The positive rates in breeding bigs, lactation piglets, weanned pigs and early fattening pigs decrease gradually, but increase again in late fattening. The comparison between vaccinated and group show the PCV 2 infection can be early in non vaccinated group and vaccination can prevent the infection.but the protection cannot maintain up to late fattening period. The homology show 94.6%-99.7% between 10 isolated strains and they mainly PCV-2b.