Immune Efficacy Evaluation Of A Recombinant Pseudorabies Virus Expressing HA Of H3N2 Swine Influenza Virus In Mice And Pigs

Influenza is a common respiratory disease in pigs, and it is a acute, feverish and infectious disease. Swine influenza virus(SIV) especially H3N2 and H1N1subtype SIV is the prevalent pathogens of SI. Swine is the only animal which can be infected by either avian or human original influenza viruses, and can be considered as the intermediate host for the process of genetic reassortments between viruses of different hosts.Generate new strains of influenza virus. Vaccination against SIV can reduce economic lose and play a role in food safety and public health.A pseudorabies virus (PRV) transfer vector pLTK-HA containing HA gene of H3N2 SIV was used to cotransfect with genomic DNA of PRV Bartha-K61 into Vero cells. After many cycles of blue plague purification and PCR identification , we got a PRV recombinant containing hemagglutinin (HA) gene of H3N2 SIV and designated as rPRV -HA. Expression of SIV HA by rPRV-HA is about 60ku as demonstrated by Western blotting analysis. Indirect immunofluorescence assay (IFA) demonstrated that HA was expressed by rPRV-HA in cytoplasm.To evaluate the immune efficacy of the recombinant as a candidate vaccine, a mouse model and native host, pigs were used successively in the experimentation. A total of 150 8-week-old female BALB/c mice were used in a mouse model. The mice were each inoculated intranasally with 10^5.0 TCID₅₀ of rPRV-HA (rPRV-HA group, n=60) or attenuated vaccine Bartha-K61 (Bartha-K61group, n=60), and another two unimmunized groups served as challenged group (n=20) or unchallenged group (n=10). Some mice in rPRV-HA and Bartha-K61 groups were sacrificed for antigen detection and virus isolation at different days post-immunization (DPI), and the others were each challenged with 10^5.0 TCID₅₀ of the same subtype SIV 28 DPI. Recombinant virus could be detected in the lungs of rPRV-HA-immunized mice. Antibody responses to PRV were detected by indirect immunofluorescence assay, but not by sero-neutralization test, in both rPRV-HA and Bartha-K61 groups. SIV-specific antibodies were detected by hemagglutination inhibition test only in rPRV-HA group 14 DPI. The rPRV-HA-immunized mice were protected from homologous SIV challenge, as indicated by limiting virus replication and pathological changes of the organs, and boosted antibody responses to SIV post-challenge.A recombinant pseudorabies virus rPRV-HA was also evaluated with a commercial porcine model. One group of 12 four-weeks old healthy piglets was inoculated intramuscularly (i.n.) with 10^5.0 TCID₅₀ of rPRV-HA, and another two control groups (five piglets per group) were mock-inoculated or inoculated with Bartha-K61. Thirty-five days post-inoculation, all piglets were...