Comparative Study Of The Effect In Different Immunization Methods Of Porcine Circovirus Type 2 Vaccine

Porcine circovirus type 2(PCV2)is an infectious virus which causes a serious loss to the swine industry.It is the major pathogen of Postweaning multisystemic wasting syndrome(PMWS),and also relates to Porcine dermatitis and nephropathy syndrome,immune deficiency syndrome in pigs,porcine respiratory syndrome,swine diarrhea syndrome,central nervous system pig syndrome.PCV2 spreads all over the world,and causes a range of diseases mainly occur in 6 to 16 weeks of age,weaned piglets.It's mainly clinical symptoms are weaned decreased appetite or waste must,pigs progressive weight loss,dyspnea,diarrhea,anemia,sometimes skin was pale or jaundice,developmental delay.Growing-finishing pigs' skin occurs round or irregularly shaped bulge,showing the central black lesions surrounding red or purple.The diseases currently focus on prevention instead of cure,virus inactivated vaccine,recombinant chimeric vaccine,subunit vaccines have played an important role in preventing PCV2 infection.However,subunit vaccines are expensive,domestic inactivated vaccine effect is still not good enough,so it's urgent to choose a new vaccine which has reasonable price and good effect.In this paper,the subunit ring vaccine produced by E.coli expression system was selected as the material,and the vaccine immunoassay test was carried out in a pig farm in Huizhou City of Guangdong Province.The experiment was carried out with the original vaccine in the pig farm.Ring virus vaccine,the main steps are as follows:We investigated and monitored the test farm's immune background and epidemics background before immunization.The farm normally immune circovirus and PRRS vaccines,but the effect of the circovirus is not good enough.1.The clinical response of pigs,growth rate,health status were observed.Theresults showed that the production of vaccination group was better than negative control.Among the four vaccination group,group B which showed the best production results,the survival rate of entire stage was 94.3%,200 d average slaughter weight was 120.65 kg.But group D which immuned other circovirus vaccine showed the worst production results.The survival rate of entire stage was 84.2%,200 d average slaughter weight was 117.94 kg.2.Then we monitored the serum antibody levels of test pigs by ELISA.The results showed that antibody positive ratewas between 75%-100% at 14 days after immunization.The group which immuned other circovirus vaccine showed the lowest positive rate(74%),and the A,B,C groups showed 100% positive rate,moreover,it could last for at least four months.3.The serum PCV2 and PRRSV infection state was monitored by quantitative PCR.The infection ratio of PCV2 and PRRSV of vaccination group(A,B,C,D)was significantly less than the negative control group(E),indicating that vaccination of PCV2 could improve the ability of infection againstPRRSV,but the difference of infection ratio of PCV2 and PRRSV among vaccination group(A,B,C,D)was not obvious.