# Identification and Characterization of Canine Parvoviruses and Emergence of Canine Bocavirus and Bufavirus from Diarrheic Dogs in Sichuan Province, China

## TL;DR

This study identifies and characterizes canine parvoviruses and newly detected canine bocavirus and bufavirus in diarrheic dogs in Sichuan, China.

## Contribution

The first report of canine bocavirus and bufavirus in Sichuan, along with novel CPV mutations and co-infection cases.

## Key findings

- CPV-2c is the dominant strain in Sichuan, replacing older CPV strains.
- CBoV and CBuV were detected for the first time in the region.
- Four co-infection cases were identified, including a triple infection case.

## Abstract

Canine diarrhea is frequently associated with viral infections. While canine parvovirus (CPV) is a well-known pathogen, two recently discovered viruses—canine bocavirus (CBoV) and canine bufavirus (CBuV)—are also recognized as potential contributors. This study investigated the presence and characteristics of these three viruses in diarrheic dogs from five regions in Sichuan, China. Our findings showed that CPV-2 (33.3%, 48/144) was the most prevalent virus. Notably, this is the first report of CBoV (5.56%, 8/144) and CBuV (4.17%, 6/144) detection in Sichuan. The dominant CPV strain identified was CPV-2c, which had replaced previously circulating strains such as CPV-2a and new CPV-2a. We also identified novel genetic mutations and documented several co-infection cases where dogs were infected with multiple viruses. These results reveal a dynamic and evolving viral situation in Sichuan’s dog population, highlighting the importance of ongoing surveillance to effectively manage disease spread and protect canine health.

Canine parvovirus (CPV) is the primary cause of viral enteritis in dogs, while canine bocavirus (CBoV) and canine bufavirus (CBuV) have emerged as significant components of the canine enteric virome. Previous studies on CPV in Sichuan had limited geographic coverage and sample size, and lacked data on CBoV and CBuV. This study used PCR to investigate the genetic diversity of CPV, CBoV and CBuV and to examine their co-infection status in diarrheic dogs across five regions of Sichuan between 2020 and 2022. The results revealed that CPV-2 was the most prevalent virus (33.3%, 48/144), while CBoV (5.56%, 8/144) and CBuV (4.17%, 6/144) were detected for the first time in Sichuan province. Genetic analysis revealed CPV-2c to be the predominant genotype (95.8% (46/48)), replacing the previously circulating strains CPV-2a and CPV-new 2a. The study also identified several typical and novel mutations in the VP2 protein in the CPV-2c strains, including Ala5Gly, Trp214Cys and Thr440Ala. Additionally, four co-infection cases (2.78%) were observed, including a triple CPV/CBoV/CBuV infection in Xichang (XC05). Phylogenetic analysis revealed genetic diversity, with CBoV strains clustering into CBoV-1 and CBoV-2 subspecies, while CBuV strains formed two distinct clusters. Our findings emphasize the need for ongoing monitoring of the dynamic epidemiological situation of CPV, CBoV and CBuV in Sichuan Province.