Study On Porcine Parvovirus And Pseudorabies Virus Recombinant Live Vaccine SA215 (B)

Biological characteristics of a recombinant PRV-PPV SA215 (B) were studied. 3 batches of vaccines were made according to manufacture protocol of national quality criteria for biological in China. Detection of all kinds of trial had passed .The keeping time, immunoprotection and latent infection were determined. All the data showed that the recombinant PRV-PPV SA215(B) was an excellent vaccine candidate strain for preventing both Pseudorabies and Porcine Parvovirus.1. Biological characteristics of the recombinant PRV-PPV SA215 (B) .Several cell lines were selected for culturing SA215(B), which confirmed that SA215(B) had broad host ranges. Vero and MDBK cells were the most sensitive cell lines. The penetration dynamics analysis and Single-step growth analysis confirmed that the deleted mutant of SA215 virus did not interfere both adsorbing and entering of PRV, which were similar to SA215. After inoculation of SA215(B),cells could cause 75~90% CPE at 36h that was the optimizing time for harvest. PRV SA215(B) was sensitive to heat and freeze thawing. PRV SA215(B) still were stable even keeping in pH5~9. Morphogenesis were normal as SA215 in cell lines. However, two types of virus particles could be found in the cells under electronic microscope: Pseudorabies virus particles, the big particles were enveloped, while the small particles were non-enveloped, which were Porcine Parvovirus particles.2. The trial-production of the recombinant PRV-PPV SA215(B) and keeping time. 3 batches of vaccines (04001, 04002, 04003) were made according to the ManufactureProtocol of National Quality Criteria for Biological. The result showed that the keeping time is one year.3. The immunogenicity and safety of the recombinant PRV-PPV SA215(B).New born piglets, weaned piglets and pregnancy sows were vaccinated with differentdosages of SA215(B) vaccine. The result indicated that the SA215(B) vaccine was safe to all kinds of pigs. In the mean time virus could not be isolated from the nasal excretion. In order to decide the minimum and different immune dosage, duration of immunity, the antibody titers at different time and the protection test against PRV Fa were preformed. The results indicated that the minimum immune dosage was lO^PFU and the protection time was 24 weeks and 26 weeks against PRV and PPV, respectively.4. The virus distribution in piglets and the anti- latent infection trial.Multiple PCR for gE/gB identification was established to distinguish SA215 (B) (gE-) from the PRV Fa (gE+). The result indicated that diffusing capacity SA215 (B) was lower than PRV Fa. SA215 (B) could replicate in local sites with low titers. this lowered the possibility of latent infection.