Multicentric molecular and pathologic study on canine adenovirus type 1 in red foxes (Vulpes vulpes) in three European countries

Canine adenovirus type 1 (CAdV-1) is the agent of infectious canine hepatitis, a severe frequently fatal disease affecting primarily dogs (Canis lupus familiaris). The virus has been detected in many wild carnivore species. Our aim was to evaluate the prevalence and genetic and histopathologic features of CAdV-1 in wild red foxes (Vulpes vulpes). Kidney and liver samples were obtained from 86 subjects, coming from the UK (n¼21), Italy (n¼36), and Germany (n¼29). We used PCR, targeting the viral E3 gene and flanked regions, to detect the presence of the virus; viral E3, fiber, and E4 genes were sequenced and their sequences were compared with published sequences. Kidneys and liver from foxes in Italy and Great Britain (n¼57) were prepared for histologic and immunohistochemical examination for CAdV-1. Viral DNA was detected in 22% (19 of 86) kidney samples, with E3 and E4 genes showing reported and unreported single nucleotide changes. No pathologic changes or viral immunopositive signals were detected in the examined tissues. Our study suggests that red foxes could be considered potential shedders of CAdV-1, as they showed a relatively high prevalence without related pathologic changes in the organs examined.