Out of the Reservoir: Phenotypic and Genotypic Characterization of a Novel Cowpox Virus Isolated from a Common Vole

• Published in: Journal of Virology
• Main Authors: Hoffmann, Donata, Franke, Annika, Jenckel, Maria, Tamošiūnaitė, Aistė, Schluckebier, Julia, Granzow, Harald, Hoffmann, Bernd, Fischer, Stefan, Ulrich, Rainer G., Höper, Dirk, Goller, Katja, Osterrieder, Nikolaus, Beer, Martin
• Format: Text
• Language: English
• Published: American Society for Microbiology 2015
• Subjects: Pathogenesis and Immunity; Brighton; Common vole
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4621121/; http://www.ncbi.nlm.nih.gov/pubmed/26311891; https://doi.org/10.1128/JVI.01195-15

The incidence of human cowpox virus (CPXV) infections has increased significantly in recent years. Serological surveys have suggested wild rodents as the main CPXV reservoir. We characterized a CPXV isolated during a large-scale screening from a feral common vole. A comparison of the full-length DNA sequence of this CPXV strain with a highly virulent pet rat CPXV isolate showed a sequence identity of 96%, including a large additional open reading frame (ORF) of about 6,000 nucleotides which is absent in the reference CPXV strain Brighton Red. Electron microscopy analysis demonstrated that the vole isolate, in contrast to the rat strain, forms A-type inclusion (ATI) bodies with incorporated virions, consistent with the presence of complete ati and p4c genes. Experimental infections showed that the vole CPXV strain caused only mild clinical symptoms in its natural host, while all rats developed severe respiratory symptoms followed by a systemic rash. In contrast, common voles infected with a high dose of the rat CPXV showed severe signs of respiratory disease but no skin lesions, whereas infection with a low dose led to virus excretion with only mild clinical signs. We concluded that the common vole is susceptible to infection with different CPXV strains. The spectrum ranges from well-adapted viruses causing limited clinical symptoms to highly virulent strains causing severe respiratory symptoms. In addition, the low pathogenicity of the vole isolate in its eponymous host suggests a role of common voles as a major CPXV reservoir, and future research will focus on the correlation between viral genotype and phenotype/pathotype in accidental and reservoir species.