# Preparation and Epitope Identification of Monoclonal Antibodies against the NS6 Protein of Porcine Deltacoronavirus (PDCoV)

## TL;DR

This study develops a specific monoclonal antibody against the NS6 protein of PDCoV and identifies a conserved epitope, aiding in understanding the virus and developing diagnostics.

## Contribution

Development of a specific monoclonal antibody and identification of a conserved epitope in the NS6 protein of PDCoV.

## Key findings

- Monoclonal antibody 5-A11 specifically recognizes the PDCoV NS6 protein without cross-reactivity to other viruses.
- The epitope recognized by 5-A11 is conserved among PDCoV isolates but differs from other δ coronaviruses.
- The identified epitope is located at residues 70EYGSIYGKDFI80 of the NS6 protein.

## Abstract

Porcine deltacoronavirus (PDCoV) is an emerging enteric pathogen that causes substantial economic losses in the swine industry worldwide. The PDCoV NS6 protein is an accessory protein that plays a pivotal role in the viral life cycle and immune evasion. However, the functions of NS6 and its role in PDCoV pathogenesis remain largely unknown. In this study, we prepared a monoclonal antibody (mAb) 5-A11 that specifically recognizes the PDCoV NS6 protein. The mAb 5-A11 exhibited high specificity for PDCoV, with no cross-reactivity with several major porcine pathogenic viruses. Furthermore, the epitope recognized by mAb 5-A11 was precisely mapped to residues 70EYGSIYGKDFI80 of the NS6 protein using Western blot analysis. Notably, this epitope is highly conserved among different PDCoV isolates. Substantial variations were observed when comparing this epitope with the corresponding regions in the NS6 proteins of other δ coronaviruses, suggesting potential differences in the structure, function, and antigenicity of their NS6 proteins. Our findings provide valuable tools and insights for further elucidating the functions of the NS6 protein and its role in PDCoV pathogenesis, as well as for developing diagnostic and therapeutic strategies against PDCoV infection.