Procaryotic Fusion Protein NP Enhanced The Serologic Immune Effect Of BPIV3 Inactivated Vaccine

Bovine parainfluenza virus type 3（BPIV3）,one of the main pathogens causing Bovine Respiratory Disease Complex（BRDC）,is distributed worldwide.In this study,a BPIV3 strain was isolated successfully from the nasal swabs of cattle suffering from respiratory diseases in a cattle farm around Hohhot,and named as 80035strain.Then,the gene sequence of NP protein was amplified by using its genome as a template,and the recombinant NP protein was obtained by using E.coli expression system.According to the result of Western blot,recombinant protein NP had strong reactogenicity.In order to verify the immunogenicity of NP protein,an immune experiment was carried out on New Zealand white rabbits.The rabbits were divided into four groups,a)inactivated vaccine group,b)NP protein group,c)inactivated vaccine+NP protein group,d)control group.Serum test including ELISA and neutralization test were performed every7 days after immunization.The serum titer of a,b,c group,detected by ELISA after 28 days immunization were2¹¹,2¹⁷,and 2¹⁸,respectively.And the result of neutralization test were 2^3.32,2^4.48,and 2^4.98.Therefore,as far as humoral immunity is concerned,BPIV3+NP group occupies first,recombinant protein NP group comes second,and BPIV3 group is the least.In conclusion,the recombinant protein NP can enhance the immune effects of BPIV3inactivated vaccine,which can be used as a new vaccination method for BPIV3 inactivated vaccine in the future,laying a foundation for the effective prevention and control of BPIV3.