| Porcine Circovirus (PCV)has genotypes PCV-1 and PCV-2, PCV-2 can cause diseases such as postweaning multisystemic wasting syndrome (PMWS), porcine dermatitis and nephrophathy syndrome (PDNS), proliferative and necrotizing pneumonia (PNP) and reproductive failure etc. Pigs suffering from PMWS may lose weight, have breathing difficulties and diarrhea progressively. Infected pregnant sows will infect their piglets through placenta. PCV-2 is widely existed in pig farms of our country, and has caused great economic losses.This experiment aims at detecting the safety and immune efficacy of the PCV2 inactivated vaccine , and evaluating the clinical application effect of the inactivated vaccine which is produced by Fuzhou Dabei Agricultural & Biological Technology Co., Ltd.The methods includes pre-test inspection, safety test of vaccines, detection of immune efficacy and clinical immune test.Pre-test inspection: Determined the appearance, formulation, stability, viscosity and mercury content of the vaccine. Detected PCV2 antigen and PCV2 antibody of test pigs , and selected the pigs which were negative of PCV2 antigen and PCV2 antibody. Safety test of vaccines: 4 piglets of 14 to 21 days old were vaccinated with 2.0ml vaccine by intramuscular injection, observed for 14 days. Detection of immunizing efficacy: 15 piglets of 14 to 21 days old were randomly divided into 3 groups, with 5 piglets in each group. Group 1 were used as immune group, inoculated with inactivated vaccine, and booster immunity 14 days later. Group 2 were used as challenge control group, injected with PCV2, and Group 3 were used as blank control group, no immuned and challenged. The 3 groups of pigs were reared separately, carried out antibody detection and pathological autopsy respectively. Clinical immune test: 450 pigs, including 350 commercial piglets, 60 replacement gilts and 40 multiparous sows , were vaccinated with inactivated vaccine of low-dose, recommended dose and overdose, observed the clinical situation, systemic and local adverse reactions, detected the mortality and PCV2 antibody levels , and 5 pigs were randomly selected from each group for pathological autopsy. The pre-test inspection of vacinne showed that the appearance, formulation, stability, viscosity, mercury content and sterility test were qualified.Safety test showed that all immunized pigs lived healthily,the mental state, behaviour and diet were normal; the respiration and body temperature were normal; There were no systemic reactions and local adverse reactions. Immune efficacy test indicated that the PCV2 antibody titer in immune group was no less than 1:800 at 21 days after the booster innoculation; 4/5 in immune group were protected; 3/5 in challenge control group fell ill, 25 days post challenge. Pathological necropsy showed that pigs in challenge control group had lung consolidation, mesenteric lymph nodes enlargement; pigs in immune group and blank control group have no significant pathological changes.Clinical immune test showed that the mental state, behaviour and diet of all immuned pigs were normal. The breath and body temperature were within the normal range; There were no systemic reactions and and local adverse reactions. The statistical result showed that the average daily weight increase of piglets in immune group were improved obviously compared with control group, the difference was significant. The pregnancy, delivery and lactation of all immuned sows were normal. The average litter size and birth weight had no significant differences compared with the control group. Autopsy revealed that there were no visible pathological changes in the pigs inoculated with overdose. The morality rate of commercial pigs in immune group was lower than control group,there were significantly difference.The PCV2 antibody of part of the test pigs in all pig farms was positive before immunization, but the antibody titer was very low. 14 days after immunization, PCV2 antibody in commercial piglets could be detected, the antibody positive rate was 40.0%～50.0%; 35 days after immunization, the antibody positive rate was over 80%, the average antibody titer was 1:1800～1:2000, which had reached protection standard. The average antibody titer in the following 5 months was beyond the protection standard (1:800). The average maternal antibody titer of 28-day-old piglets borne by immunized sows was 1:1720～1:1800, and The antibody titer reduced to 1:800 at 35-day-old.It is conclued that the inactivated vaccine was safe. After immunizing with this inactivated vaccine, neither commercial pigs nor pregnant sows have adverse reaction. The inactivated vaccine has good protective effect on immunized pigs.
|
PDF Full Text Request