# Fecal Microbiota Changes in Angus Beef Cows Persistently Infected by Bovine Viral Diarrhea Virus

## TL;DR

Persistent BVDV infection in cows changes gut bacteria, lowers diversity, and increases inflammation, which could weaken disease resistance.

## Contribution

The study identifies specific gut microbiota changes and metabolic shifts caused by persistent BVDV infection in cattle.

## Key findings

- Persistent BVDV infection reduces gut microbial diversity and increases inflammation-linked bacteria like Paludibacter.
- PI cows show elevated histidine metabolism, a pathway associated with inflammation.
- Ruminococcus is more abundant in persistently infected cows compared to controls.

## Abstract

Bovine viral diarrhea virus (BVDV) severely impacts cattle health and farm economies through persistent infections. This study compared the gut microbiota of cows persistently infected (PI) with BVDV to uninfected controls and rigorously confirmed the results via ELISA and PCR to exclude both transient and chronic infections. Persistent BVDV infection altered the gut microbiota, reducing microbial diversity and driving inflammation-associated dysbiosis. PI cows showed reduced microbial diversity, with fewer beneficial bacteria, including Ruminococcus, and more inflammation-linked Paludibacter. Increased histidine metabolism activity—a pathway tied to inflammation—was observed in PI cows. These changes suggest that BVDV weakens gut health, potentially lowering disease resistance. The findings highlight the importance of balancing the gut microbiota in cattle health, providing actionable insights for managing BVDV. By understanding how viruses alter gut ecosystems, new strategies to improve herd resilience against BVDV infections could be developed.

Bovine viral diarrhea virus (BVDV) remains a major cause of calf diarrhea with substantial economic impacts on global cattle production. While emerging evidence suggests that the host microbiota may modulate viral infection processes, the specific gut microbial alterations induced by BVDV infection require elucidation. This study investigated gut microbiota composition and functional changes in BVDV-infected cows through 16S rRNA sequencing. Following the epidemiological screening of a large Angus cattle herd using RT-PCR, we identified four persistently infected (PI) animals and four BVDV-negative controls. Fecal analysis revealed Firmicutes and Bacteroidetes as dominant phyla in both groups. A significant increase in the Ruminococcus genus was observed in PI cows (p < 0.05), with LEfSe analysis identifying Paludibacter as a BVDV-associated biomarker. The PI group exhibited reduced alpha diversity (Faith’s PD index, p < 0.05) and elevated histidine metabolism pathway abundance compared to controls (p < 0.05). These findings demonstrate that persistent BVDV infection induces structural and functional modifications in the bovine gut microbiota, particularly through the enrichment of specific bacterial taxa and altered metabolic potential. The results provide new insights into virus–microbiota interactions, establishing a foundation for understanding how BVDV infection may influence host physiology through microbial community changes.