Distribution of Borna disease virus antigen and RNA in tissues of naturally infected bicolored white-toothed shrews, Crocidura leucodon, supporting their role as reservoir host species.
Authors: Puorger M E, Hilbe M, Müller J-P, Kolodziejek J, Nowotny N, Zlinszky K, Ehrensperger F
Journal: Veterinary pathology
Summary
Borna disease virus causes serious neurological disease in horses and sheep across central Europe, yet its transmission cycle remains poorly understood; this work investigated whether small mammals might serve as reservoir hosts. Two naturally infected bicolored white-toothed shrews (*Crocidura leucodon*) trapped in an endemic region were examined using immunohistochemistry and real-time RT-PCR to map viral distribution across tissues. BDV antigen and RNA were detected not only in neural tissue as expected, but also widely distributed throughout hepatocytes, Leydig cells, and epithelial cells lining the respiratory and urogenital tracts—despite neither animal displaying clinical signs of disease. These findings provide compelling evidence that shrews can maintain persistent BDV infections without overt pathology, suggesting they function as asymptomatic reservoir hosts and may represent a critical epidemiological link in BDV transmission to equine and ovine populations. Understanding this reservoir dynamic is essential for veterinarians and stud managers in endemic regions to develop more effective biosecurity strategies, particularly regarding exposure risk and potential wildlife–domestic animal contact points.
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Practical Takeaways
- •This research provides evidence that shrews may be a natural reservoir for Borna disease virus in central European endemic areas, helping explain the epidemiology of equine BDV cases
- •The asymptomatic carrier status in shrews suggests that environmental exposure to infected wildlife may be a source of BDV transmission to horses and livestock in endemic regions
Key Findings
- •BDV antigen and RNA were detected in multiple organs of naturally infected shrews including brain, liver, respiratory tract, and urogenital tract without clinical disease signs
- •Virus distribution included both neural tissue (neurons and nerve cells) and parenchymal/epithelial cells, suggesting multi-organ involvement
- •Bicolored white-toothed shrews (Crocidura leucodon) can harbor BDV infection asymptomatically, supporting their role as a natural reservoir species in endemic regions