# Identification of a Novel Antigenic Epitope in Envelope Protein of Avian Reticuloendotheliosis Virus

## TL;DR

Researchers identified a new immune-targeting region in a virus that causes poultry disease, which could help improve detection methods.

## Contribution

Discovery of a novel conserved linear B-cell epitope in the envelope protein of reticuloendotheliosis virus.

## Key findings

- A hybridoma cell line was developed to produce monoclonal antibodies against the REV gp90 protein.
- The epitope 195REESVRERL203 was identified as a conserved and accessible region on the gp90 protein.
- The study provides insights into the antigenic structure of REV for improved detection and vaccine development.

## Abstract

Reticuloendotheliosis is a devastating poultry disease causing tumors and immunosuppression in infected birds. Reticuloendotheliosis virus (REV) encodes a surface glycoprotein (gp90) that mediates viral infection, assembly, release and induces protective antibodies. However, the specific gp90 regions triggering immune responses have not been fully characterized. In this study, we expressed gp90 of a prevalent REV strain using a prokaryotic expression system and established a hybridoma cell line stably secreting gp90-specific monoclonal antibodies through cell fusion and flow cytometric screening. Most notably, we identified a novel conserved linear B-cell epitope, 195REESVRERL203, on the outer side of gp90 for the first time. This study is of great significance for the systematic understanding of REV antigen structure and the development of virus detection methods.

Avian reticuloendotheliosis (RE) caused by reticuloendotheliosis virus (REV) is an important tumor and immunosuppressive disease posing a serious threat to poultry development. The REV envelope protein, glycoprotein (gp)-90, not only participates in cell receptor binding and viral assembly and release but also induces neutralizing antibody production. However, the antigenic epitope structure of gp90 has not yet been systematically understood. Therefore, in this study, the gp90 envelope protein of a predominant REV strain was prepared using a prokaryotic expression system, and a hybridoma cell line stably secreting the REV gp90 monoclonal antibody was developed via cell fusion and flow cytometry. Notably, a novel linear B-cell epitope, 195REESVRERL203, was identified for the first time in the gp90 of REV using peptide scanning. This epitope was located on the outer side of the gp90 midpiece and was conserved across REV strains. Overall, this study is of great significance for the systematic understanding of REV antigen structure and the development of virus detection methods.