# Immunogenicity of subunit vaccine of E2 protein against atypical porcine pestivirus in pigs

## TL;DR

Researchers developed a subunit vaccine using the E2 protein of atypical porcine pestivirus (APPV) and found it can trigger an immune response in pigs, potentially preventing APPV infection.

## Contribution

The study demonstrates the successful expression of APPV E2 protein in E. coli and identifies effective adjuvants for a subunit vaccine against APPV.

## Key findings

- The E2 protein was successfully expressed in Escherichia coli and induced IgG responses in piglets.
- Vaccines with ISA 201VG and Gel 02 adjuvants produced higher antibody levels than IMS 1313VG.
- The ISA 201VG-adjuvanted vaccine provided protection against APPV infection and showed normal organ morphology in vaccinated pigs.

## Abstract

An atypical porcine pestivirus (APPV) causes congenital tremor (CT) type A-II in piglets and has caused considerable financial losses to the pig industry worldwide. This study aimed to develop an effective vaccine candidate against APPV.

We constructed a prokaryotic expression system for the APPV E2 protein in Escherichia coli. The immunogenicity of the APPV E2 subunit vaccine, formulated with three different adjuvants (ISA 201VG, IMS 1313VG, and Gel 02), was evaluated in piglets. Assessment was based on E2-specific antibody levels measured by an in-house enzyme-linked immunosorbent assay (ELISA) and protection against an APPV challenge. Successful expression of the E2 protein was confirmed by western blot analysis.

The E2 protein was successfully expressed, and an E2-ELISA detection method was established. Vaccinated piglets mounted virus-specific IgG responses. The E2 protein emulsified with ISA 201VG and Gel 02 adjuvants induced significantly higher antibody levels than the formulation with IMS 1313VG adjuvant. The vaccine with ISA 201VG adjuvant yielded the highest antibody levels and provided protection against APPV infection. Histopathological examination confirmed normal organ morphology in vaccinated pigs, whereas the control group displayed significant pathological alterations.

The results demonstrate that the Escherichia coli-expressed E2 protein elicits an immune response in pigs. The E2 subunit vaccine is a potential candidate for preventing APPV infection, and ISA 201VG and Gel 02 adjuvants are suitable candidate adjuvants for vaccine preparation. This study provides a foundation for further APPV vaccine research.