Epatite virale da adenovirus canino tipo 1: indagine retrospettiva su ceppi virali identificati in fegati inclusi in paraffina

From the Seventies, widespread vaccination has allowed an effective control of the infectious canine hepatitis (ICH) caused by the canine adenovirus type 1 (CAdV-1). However, cases of ICH are still reported. To assess the genetic differences between the Italian CAdV-1 strains spreading in the dogs population before the introduction of extensive vaccination and the strains recently identified, a retrospective study was performed on sections of paraffin-embedded liver of dogs with histological lesions typically related to CAdV- 1 infection. Eight dogs dead in 1961-69 and a dog dead in 2010 were selected and diagnosis of CAdV-1 infection was performed on DNA extracted from paraffin-embedded tissues by amplifying a portion of the E3 gene. The analysis performed on the obtained nucleotide sequences and reference sequences showed a complete identity between the viruses identified in dogs dead before the 1970, and behveen them and viruses identified in recent years in Italy. Therefore, these results suggest that before the vaccination against ICH, a single strain of CAdV-1, or very similar strains, was circulating in Italy and that it may still be present on the national territory. This hypothesis needs to be confirmed by increasing the number of infected dogs tested and analysing larger portions of the viral genome. In addition, the ability of molecular tests performed on old histological preparations to give positive results has important implications in the retrospective diagnosis and in the study of viral evolution.