Preparation And Field Experiment Of The Mixed Inactivated Vaccine Of Porcine Parvovirosis, Pseudorabies And Porcine Reproductive And Respiratory Syndrome

Infectious diseases of pigs become complicated increasingly. Vaccinations may cause animal stress and decrease productivity and repeated vaccinations were unprofitable. Consequently, it is necessary to develop mixed vaccine. The key technique to develop this vaccine with high immunologenicity is to condense antigen. Some techniques were applied on preparation and field experiment for the mixed inactive vaccine of porcine parvovirosis/pseudorabies/porcine reproductive and respiratory syndrome.The propagation conditions of PPV, PRV were optimized. The results showed that the PPV-L strain grew better on ST and PK-15 cell lines than on Marc-145 cell lines and the virus titer reached to 106.61TCID50/0.1mL. The optimum medium, fetal bovine serum, pH, harvest time and freeze-thawed times were MEM and TC199, 10%FCS, 7.0, 72h and 3 times respectively.The virus titer of PRV-L strain propagated on RK cell lines could be 107.0TCID50/0.1mL. The optimum medium, fetal calf serum, pH, harvest times and freeze-thawed times were DMEM, 8-10%. 7.0-7.2, 48-60h, 2 times respectively.The PPV, PRV and PRRSV were inactived by formaldeyde and stopped at regularly intervals, inactivating effects were detected by observation of the cytopathic effects (CPE) of infected cells. On the condition of 37℃ and 0.1% formaldeyde , the inactived time of PPV, PRV and PRRSV was 48,24,24 hours respectively.The cell cultures of PPV, PRV, PRRSV were inactived by 0.1% formaldeyde , then they were condensed in 2/3 volume by PEG20000 and mixed with the same ratio .The immunity and field experiment of 23 gilts and 514 pregnant sows showed that the mixed vaccine immunity against PP/PR/PRRS was equivalent to the single vaccine in four months.In the field experiment ,the average surviral rate per litter was up to 9.725 from 7.12 and stillbirth and mummy were dropped to23.6%. 20 piglets and 12 sows pregnanted80 days were tested to evaluate the safety .Inoculating 4 lot mixed vaccine ,it was safety to piglets and pregnant sows that the immunizing dose was twofold and fourfold as much as normal respectively.