# Establishment of an infectious clone of the porcine transmissible gastroenteritis virus and a study on the location and function of accessory protein 3

## TL;DR

Researchers created a modified version of a pig virus to study a protein's role in immune response and vaccine development.

## Contribution

Established a reverse genetic system for TGEV and demonstrated the role of ORF3 in immune response modulation.

## Key findings

- ORF3 is a non-structural protein not present in mature virions.
- rTH-98-Δ3-COE-HA induces lower inflammatory cytokine levels than wild-type TGEV.
- The recombinant virus induces specific immune responses against exogenous proteins in mice.

## Abstract

Transmissible gastroenteritis virus (TGEV), as the causative agent of TGE, causes huge economic losses in the pig industry worldwide.

In this study, we successfully constructed a reverse genetic system for the TGEV TH-98 strain and rescued the recombinant virus rTH-98-Δ3-COE-HA based on this system.

The results showed that ORF3 is a non-structural protein and does not exist in mature virions. Therefore, rTH-98-Δ3-COE-HA induced inflammatory cytokine expression in IPEC-J2 cells, but the expression levels were significantly lower than those triggered by TH-98 and rTH-98, indicating that TGEV ORF3 may play a critical role in inducing the host immune response. To detect whether the exogenous protein expressed in the rTH-98-Δ3-COE-HA has immunogenicity, the results showed that the levels of antibodies were significantly increased in mice. rTH-98-Δ3-COE-HA can induce a specific immune response in the host body against its expressed exogenous proteins.

Our study provides important clues for revealing the role of ORF3 in virus replication and pathogenesis, laying a theoretical and material foundation for the construction of recombinant viral multi-valent vaccines.