Study On Inactivated Vaccine Against Porcine Circovirus 2 And Recombinant Adenovirus Expressing Cap Protein

Porcine circovirus 2(PCV2) is the main causative agent of postweaning multisystemic wasting syndrome(PMWS). The disease is characterized by progressive weight loss, dyspnea, respiratory signs and jaundice, combined with pathological findings of interstitial pneumonia, generalized enlarged lymph nodes, hepatitis and nephritis. The disease was first identified in a swine herd in Canada in 1991 and then since has been reported in pigs throughout the world. Now PMWS still remains a major problem in the swine population.In this study, porcine circovirus 2 was inactivated with 0.2% formaldehyde under 37℃, then was passaged on PK-15 cell three times and the inactivation effect was estimated by PCR method. The immune efficiency of the oil-adjuvant and the Aluminum Hydroxide-adjuvant inactivated vaccines against PCV2 was evaluated in mice. Mice were vaccinated subcutaneously twice at a three-week interval. The specific ELISA antibody against PCV2 was detected at days 21 and 35 after the first immunization. In order to evaluate the immune efficacy between the homemade oil and overseas oil, piglets were immunized with inactivated PCV2 vaccines. The efficacy of vaccines were evaluated by seroconversion, clinical signs (fever), gross lesions, growth parameters and viremia. The results were: ① PCV2 was inactivated completely with 0.2% formaldehyde by 16 h. ② The better immune response could be induced by two vaccines in mice and the immune efficiency of the oil-adjuvant inactivated vaccine was better than that of the Aluminum Hydroxide-adjuvant inactivated vaccine. (3) The higher ELISA antibody titers of two oil-adjuvant vaccines could be detected in piglets after second immunization. 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 group. The positive average weight growths were observed in two immunized groups and mock group, but minus average weight growth in challenge control group. Comparison of average daily weight growth (ADWG) of vaccinated pigs with that of mock pigs revealed statistically significant difference existed between them (P<0.05). At day 21 post challenge viremia was detected in all pigs in challenge control group but not...