Study On Virus-Like Particles Of Feline Parvovirus

Feline Panleukopenia is a highly infectious disease caused by Feline Panleukopenia Virus（FPV）,which mainly infects cats and other felines.Because FPV poses a serious threat to companion animals and the captive animal industry,prevention of FPV epidemics is of great importance.The main methods of prevention for FPV are inactivated and attenuated vaccines,which have some disadvantages including easy denaturation of antigenic proteins,reversion of virulence and apparent lack of vaccine efficacy.In this study,the virus-like particles were prepared by using E.coli expressing FPV VP2 protein for solving the above problems.Full gene sequence of FPV VP2 obtained from Gen Bank.The VP2 gene was optimized by using bioinformatics software.The VP2 nucleic acid sequence was synthesized artificially.After the expression vector p ET30a-VP2 was constructed,p ET30a-VP2 and the molecular chaperone plasmid p TF16 were co-transferred into E.coli ER2566 cells.SDS-PAGE electrophoresis results showed that p TF16 increased the proportion of soluble protein expression.Western blotting results showed that the VP2 protein was 65 ku in size and had good immunoreactivity.The VP2 protein was initially purified by using ammonium sulphate.Saturated ammonium sulphate solutions at final concentrations of 15%,20%,25%and 30%were used for the salting of VP2 protein.The SDS-PAGE results showed that at a final concentration of 25%saturated ammonium sulphate,the heteroproteins were removed in large quantities,and the purity of VP2 protein was 68.78%.The VP2protein was further finely purified by hydrophobic chromatography.The VP2 protein was eluted at 11%-37%B pump elution.The purity of protein was 90%.The concentration of protein was 0.32 mg/m L.The hemagglutination titer of the purified VP2 protein was 2¹³.BALB/C mice aged 6 to 8 weeks were immunized with FPV virus-like particle vaccine,and serum was collected for detection of hemagglutination inhibition（HI）antibody level and specific antibody level.Body weight and of the mice were also monitored.The results showed that the weight of mice in each group increased with age,and their mental state was good.Compared with the PBS control group,FPV VLPs specific binding antibodies were detected at 1 and 2 weeks after immunization,and the highest titer was 1:2¹⁵in the high dose group at 5 weeks after immunization.HI antibody could be detected in 2 weeks after immunization,but the titer was low.After 4 weeks,HI antibody titer increased significantly.At the fifth week,the antibody level reached the highest,and the titer of HI antibody was 1:2⁹.The results indicated that FPV virus-like particle can induce a good immune response.