| Pig pseudorabies（PR）causing serious economic losses to the pig industry,because of a high mortality rate.Vaccine immunization is an effective means to prevent and control this disease,but since 2011,pseudorabies virus（PRV）infection immunized herds again,the cause of the outbreak is still controversial.Therefore,this study’s purpose is to isolate the epidemic strains,to analyze the antigenicity and immunogenicity,in order to analyze the causes of the re-prevalence of the pseudorabies virus.This research will provide data support and theoretical basis for the prevention and control of the pseudorabies virus in pigs.In this study,pig brain tissue which the result of PRV gE gene PCR is positive by Vero cell culture to isolate virus strains.The morphology of the virus particle was identified by electron microscopy as a diameter of about 150 nm,obvious outside capsule.Indirect immunofluorescence detection revealed that the virus-infected cells exhibited specific fluorescence,and it was determined that the virus was PRV.To the gene sequence comparative analysis find that this strain was in the same branch with the PRV strain isolated in recent years,but it was far away from traditional strains and foreign strains.The results showed that the strain was mutated and named it PRV GD1406 strains.The serological investigation of swine pseudorabies in Guangdong area,collec the serum of pigs immunized with Bartha-K61.Filtering gB antibodies is positive and gE antibodies is negative were screened by ELISA,and Bartha-K61 and PRV GD1406 were used as antigens to Serum neutralizing antibody test.The results showed that the median neutralizing antibody titers of Bartha-K61 and PRV GD1406 wild-type strains were 1:57and 1:13,respectively.Indicating that the serum had a higher neutralizing capacity for Bartha-K61 than PRV GD1406.PRV GD1406 antigenicity may mutate.This indicates that the Bartha-K61 vaccine may not be effective against the new variant PRV.Inoculation of BALB/c mice with a lethal dose of 100 LD50 Bartha-K61 and PRV GD1406 strains was performed on the back of the neck.The results showed that the Bartha-K61 strain was able to provide protection rate is 20%against the lethal challenge of PRV GD1406 wild-type strains,and PRV GD1406 is 40%,indicating that mice immunized with PRV GD1406 better than Bartha-K61,providing an alternative strain for new vaccines.In this study,a strain of PRV GD1406 was isolated from a pig farm where PR was once again prevalent.The cross-neutralization test showed that antigenic variation occurred in the new epidemic strain,which was one of the reasons for the re-prevalence of the Bartha-K61 vaccine.Through the mouse immune protection model PRV GD1406 strain inactivated vaccine doubled the protection rate,and the vaccine can not be inactivated after inactivation in the body and other factors lead to poorer immune effects than live attenuated vaccines,further suggesting that PRV GD1406 strain became vaccine preparation.The potential of selected strains.This study analyzes the reasons why the current market vaccine cannot provide effective protection for PRV-transformed swine herds,provides a reference for prevention and control of swine pseudorabies,and provides data support and new ideas for the development of effective control of new swine pseudorabies vaccines. |
