Abstract:

This study aims to explore the effects of different adjuvants on the immunogenicity of Transmissible gastroenteritis virus (TGEV) S protein and Porcine epidemic diarrhea virus (PEDV) S protein. IPTG-induced recombinant expression strains Rosetta (DE3)-pET28a-TGEV-S2/3 and BL21 (DE3) -pET28a-PEDV-S1/2/3 were used to prepare recombinant proteins TGEV-S2, TGEV-S3, PEDV-S1, PEDV-S2 and PEDV-S3, and to conduct SDS-PAGE and western blot identification. The recombinant protein was mixed with three types of adjuvants, ISA 71VG, ISA 201VG and ISA 15AVG respectively, to prepare immunogen which was used to vaccinate layers. Western blot was used to detect serum antibody titer of layers, and immunoperoxidase monolayer cell staining assay (IPMA) was used to detect antibody and pathogen reactivity. The average daily weight gain of the flock was monitored. The results showed that the molecular weights of recombinant proteins TGEV-S2, TGEV-S3, PEDV-S1, PEDV-S2 and PEDV-S3 were 25 ku, 28 ku, 26 ku, 24 ku and 21 ku, respectively. Western blot analysis showed that all the five proteins had good immunogenicity. The highest antibody titer was 64000 times, 32000 times and 8000 times respectively in the ISA 201VG adjuvant group, ISA 71VG adjuvant group and ISA 15AVG adjuvant group, while no specific antibody was detected in the control group. The ISA 71VG and ISA 201VG group had a relatively large decrease in the egg production rate, while the ISA15AVG adjuvant group had a relatively small impact on the egg production rate, and the egg production rate in the experimental group returned to normal 7 days after immunization. The average daily weight gain of layers in the ISA 71VG adjuvant group was significantly decreased; while the average daily weight gain of layers in the ISA 201VG and ISA 15AVG adjuvant group was not significantly different from that in the control group. The serum antibody of ISA 201VG group had good reactivity with neutralization titer up to 1:256. The immune effect of the vaccine with ISA 201VG adjuvant was better than that of the other two adjuvants.

Key words: swine transmissible gastroenteritis virus S protein, porcine epidemic diarrhea virus S protein, adjuvant, antibodies, immunogenicity