# Molecular epidemiology of group A rotavirus (RVA) and bovine coronavirus (BCoV) associated with neonatal calf diarrhea in Türkiye

## TL;DR

This study examines the prevalence and genetic diversity of RVA and BCoV in neonatal calves with diarrhea in Türkiye, highlighting the need for updated control strategies.

## Contribution

The study provides new insights into the molecular epidemiology and genotype diversity of RVA and BCoV in Türkiye.

## Key findings

- RVA was detected in 32.3% of samples, with G10P[11] and G6P[5] as the predominant genotypes.
- BCoV was found in 7.9% of samples and showed genetic similarity to classical strains.
- Uncommon RVA genotypes like G8P[5] and G6P[1] were identified, indicating diverse strain circulation.

## Abstract

Neonatal calf diarrhea is mainly associated with group A rotavirus (RVA) and bovine coronavirus (BCoV), continuing to pose a major issue in livestock due to its high prevalence and economic impact. This study aimed to investigate the prevalence, molecular features, and genotype diversity of RVA and BCoV in fecal samples from 213 diarrheic calves under 28 days old, collected across various regions of Türkiye. Using antigen ELISA, RVA was detected in 32.3% (n = 69), BCoV in 7.9% (n = 17), and coinfection in 1.8% (n = 4) of samples. Out of 69 samples that tested positive for RVA, 53 were confirmed using the RT-PCR method, targeting the VP6 gene. The predominant genotype combinations were G10P[11] and G6P[5], whereas G8P[5], G6P[11], and G6P[1] were detected at lower frequencies. The presence of the rarely observed G8P[5] and G6P[1] genotypes in Türkiye indicates the circulation of uncommon strains and underscores the necessity for continued genotyping surveillance. SDS-PAGE analysis showed a typical 4/2/3/2 electrophoretic pattern for Group A rotaviruses. For BCoV, nested RT-PCR targeting the N gene confirmed infection in 13 of 17 ELISA-positive samples. Phylogenetic analysis of three selected samples from three provinces demonstrated that the analyzed BCoV sequences clustered within the genus Betacoronavirus and showed genetic similarity to classical BCoV strains. The findings suggest genetically diverse RVA strains and more conserved BCoV strains are co-circulating in Türkiye. Despite vaccination and biosecurity measures, the ongoing presence of RVA and BCoV in neonatal diarrhea cases highlights the need to reassess control strategies and align vaccine formulations with the molecular profiles of circulating strains.