# A Novel Pathogen of an Emerging Infectious Disease (Large Kidney Disease) in Farmed Blue Foxes

## TL;DR

A new virus, PreXMRV-20, was identified as the cause of large kidney disease in farmed blue foxes in China, raising concerns about public health due to its zoonotic potential.

## Contribution

The first isolation and characterization of an XMRV homolog in blue foxes, linking it to an emerging infectious disease.

## Key findings

- PreXMRV-20 was identified in diseased blue fox tissue with 82.6% homology to XMRV.
- PreXMRV-20 infection in weaned foxes caused growth retardation.
- Nonenveloped, polygonal virus-like particles were observed, consistent with XMRV morphology.

## Abstract

An emerging infectious disease (EID) in foxes called “large kidney disease”, characterized by enlarged kidneys, has been breaking out in fox farms in China, although its pathogenesis has not yet been elucidated. Here, we performed viral metagenomics sequencing on diseased fox tissue samples that identified a virus with 82.6% homology to the xenotropic murine leukemia virus-related virus (XMRV) PreXMRV-1 provirus strain (GenBank accession number NC_007815.2) in sick fox tissue. It was named PreXMRV-20, and its genome was verified by reverse transcription-polymerase chain reaction (PCR) and PCR product sequencing. Nonenveloped and polygonal virus-like particles consistent with the shape and size of XMRV were observed by negative staining electron microscopy. Administered subcutaneously, PreXMRV-20 infected weaned foxes, leading to growth retardation. The discovery of the PreXMRV-20 strain (the first isolation of an XMRV homolog in blue foxes) identifies a potential public health issue in blue fox breeding since XMRV has been confirmed to be a zoonotic virus.