| Pesudorabies(PR)is an acute infectious disease caused by pseudorabies viurs(PRV),also known as Aujeszkyps Disease(AD).It is a high degree of fatal disease.The main symptoms include itching,fever and encephalomyelitis.Spectrum of infection is very broad which includes pigs,horses,cattle,sheep,dogs,cats,mice and a variety of wild animals.The main host and the source of infection of this disease is pigs.Healthy pigs can be infected by direct contact with the sick pigs or pigs with the PRV.Vaccination is the main measure to control and eradicate PR.The classical Bartha-K61 strain of live attenuated vaccine plays an important role in the prevention and eradication of pseudorabies.Current live vaccines against pseudorabies are safe for pigs,but may be pathogenic to other species.The domestic pig farm environment is complex,often suffering from rodents,pig's waste and related waste materials can not be guaranteed without being eaten by the dogs,cats and mice.If these live vaccines are pathogenic to non-target animals,it is possible to cause infections in dogs,cats and mice which leads to a certain risk of biosecurity.In order to test the safety of pseudorabies live vaccine against other species,BALB / c mice were used as experimental subjects to evaluate the commercialization of Bartha-K61 vaccine strain,HB-98 vaccine strain and the lack of TK gene of Bartha-TK- strain constructed in our laboratory on safety of mice.Next,the vaccine strains were continuously subcultured in mice and then infected with pigs to study whether it will produce pathogenicity on pigsto initially assess the biosafety risk of using the existing TK+/TK- porcine pseudorabies live vaccines.In this study,the one-step growth curve of porcine pseudorabies live disease Bartha-K61,HB-98 and Bartha-TK- on PK-15 and NRK cells were measured.The results showed that Bartha-K61 proliferated fastest on PK-15 cells,After 20 hours,the titer of HB-98 was significantly lower than that of the other two vaccine strains;On the NRK cells,HB-98 proliferated fastest and the titer was the highest,Bartha-TK- was started to proliferate after 24 hours and the titer was the lowest.The plaque morphology of the three vaccine strains on the two cells was compared.The results showed that the plaques formed on the two kinds of cells were not homogeneous,and the maximal plaque diameter of the three vaccine strains on PK-15 cells was basically the same.The plaque diameter of HB-98 strain on NRK cells was significantly larger than that of the other two vaccine strains.This study carried out the safety evaluation of porcine pseudorabies live vaccine Bartha-K61,HB-98 and Bartha-TKto study the safety of porcine pseudorabies live vaccine in mice.Continuous passassing five generations of viruses in mice,the supernatant of the brain tissue suspension containing the fifth generation of viruses was inoculated with 2 weeks old piglets to test whether the pathogenicity will be enhanced.The results showed that Bartha-TK- and HB-98 strains were safe to mice and the Bartha-K61 strain was not safe to mice.The PRV could not be detected in the tissues and organs from the mice which inoculated Bartha-TK- and HB-98 stain,so there was no continued generation test in mice.Bartha-K61 was inoculated in mice for five generations and then inoculated with piglets.The results showed that there were no significant clinical symptoms in the pigletswhich indicating that there was no pathogenicity in the piglets by 5 passaging on mice. |
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