# Characteristics of an emerging canine respiratory coronavirus in China

## TL;DR

This study identifies a new variant of canine respiratory coronavirus in China with unique genetic features and increased pathogenic potential.

## Contribution

The paper reports the discovery of a novel CRCoV variant with distinct genetic mutations and pathogenic traits in China.

## Key findings

- Five CRCoV genomes formed a distinct genetic branch, showing unique evolution.
- Mutations in HE lectin domain (S158F and L161F) suggest increased receptor-binding affinity.
- Experimental infection confirmed the variant's ability to cause pneumonia and tracheal cilia loss in dogs.

## Abstract

Canine respiratory coronavirus (CRCoV) is a prevalent pathogen implicated in canine infectious respiratory disease, yet information on its genomic characteristics and pathogenicity remains scarce. To address this situation, we investigated the genetic evolution and pathogenic potential of CRCoV strains circulating in China. Five complete CRCoV genomes (GenBank: PQ725948–PQ725952) were obtained from clinical samples, and phylogenetic analysis showed these strains formed a distinct genetic branch. The evolutionary trees for ORF1ab, HE, and S genes closely mirrored the full genome tree, indicating key roles for these genes in CRCoV evolution. Multiple unique amino acid mutations were identified in the ORF1ab, HE, S, M, and N proteins. Notably, molecular docking analysis suggests that mutations S158F and L161F in the HE lectin domain are associated with improved docking scores, indicating a potential increase in receptor-binding affinity. Consecutive nucleotide deletions in two non-coding regions between non-structural protein genes—which were also identified in strains of a Thai lineage (OQ621707.1–OQ621727.1)—were observed. A CRCoV strain (106 TCID50/mL) was isolated, and experimental infection confirmed its ability to induce pneumonia and tracheal cilia loss in dogs. These findings reveal the emergence and unique genetic diversity of a novel CRCoV variant in China, highlighting the need for ongoing epidemiological surveillance.