Abstract
Bovine adenovirus type 2 (BAdV-2), a member of the Mastadenovirus genus of the Adenoviridae family, is involved in mild respiratory disease and is rarely isolated from cattle in the world. Here, we isolated BAdV-2 for the first time in Japan, from the feces of cattle with severe respiratory symptoms. The isolate, designated strain KY19-1, was identified morphologically and genetically. Electron microscopic observation of infected cells showed intranuclear, non-enveloped virus particles, approximately 70 nm in diameter and with typical adenoviral morphology. Whole-genome sequencing revealed that the viral genome is 33,175 bp long, with 105 bp inverted terminal repeats and encoding 32 predicted genes. KY19-1 has a similar genomic organization to the prototype BAdV-2 strain No. 19 with overall 99.1% nucleotide identity. Notable differences were found in the E3 region of the genome, which may affect various biological properties, including pathogenicity. The seroepidemiology of BAdV-2 was also investigated, using a virus-neutralization test, and 92.8 % of the Japanese cattle (n=1,325) were seropositive, with the positivity rate increased by age. Further experimental infections with KY19-1 may elucidate the pathogenic properties of BAdV-2 and the importance of this virus as a causal agent of bovine respiratory disease.
Epidemic of Bovine Adenovirus type 2 Associated with Respiratory and Digestive Signs in Dairy Cattle
