Effects Of PCV2 Immunization In Pigs And Genetic Variation Analysis Of PCV2 Isolates

Porcine Circovirus Type 2(PCV2)has a higher infection rate in swine,it can cause pig disease and also causes immune system damage,causing a variety of diseases.Vaccination of vaccines can reduce the risk of PCV2 to immunized pigs,the virus load in the organization,but also provides the basic conditions for the pig farm PCV2 purification.The level of antibody after immunization was the main index to evaluate its effect.The detection of PCV2 virus in immune pigs was the most direct indicator to evaluate the effect of vaccine.During the professional internship,I mainly engaged in the evaluation of immunization effect of PCV2 vaccine,have collected seven long-term adhere to the PCV2 pig farms pig serum,two did not carry PCV2 vaccine immunized pig serum samples.We detected the serum antibody and virus in order to explain the role of vaccine immunization in the prevention and control of porcine circovirus disease from the aspects of antibody level and virus clearance.Based on the analysis of the relationship between vaccine immunization and viral infection,the rep and cap gene was cloned into PCV2 nucleic acid positive samples,and then the sequence genetic variation was analyzed.The study can analyze the causes of PCV2 infection from the level of nucleic acid and also can provide basic information for vaccine development.This study obtained the following results:1.The positive rate of antibodies was 65.17%(116/178)from 178 sera of 7 PCV2 vaccines,the highest positive rate was 90.20%,and the lowest was only 26.67%.The positive rate of antibody in the 84 sample from two non-PCV2 vaccines immunized farms was 15.48%(13/84).2.Six of the 262 serum samples were positive for PCV2,accounting for 2.29%(6/262).The positive rates of PCV2 were 3.33%(1/30)and 9.09%(1/11)respectively in serum from 2 field vaccines in 7 vaccine immunization sites.The positive rate of non-immunized pig farm 1 was 2.86%(1/35)and the pig farm 2 was 6.12%(3/49).3.The specific antibodies of PCV2 nucleic acid positive samples were negative.4.The homology of the rep gene sequences of the six isolates was 97.3% ~ 99.8%,the homology of GS1,3,4 was higher,the GS2,5,6 homology was higher,GS1,3,4 And GS2,5,6 homology is low.5.There were some genetic differences between the six isolates and the isolates at home and abroad.The highest homology of the cap gene was 98.1% and the lowest was 87.7%.They belonged to a large branch in the phylogenetic tree and there is a high homology between the isolated PCV2 d gene subtype of the virus.