Adenovirus

Bovine adenovirus 7 (BAdV-7) is an unclassified member of the genus Atadenovirus with a worldwide distribution and has been reported to induce clinical ...

Our data also supports a recent analysis highlighting interspecies variability within the fiber gene (39.56% aa sequence identity to OAdV-7) [ 4]. We also identified the BAdV-7 genome region displaying the highest levels of intraspecies nucleotide sequence variability of BadV-7 to be in the genome region between the genes E4.1 and RH5. As previously described, this region is missing the gene RH6, which is present in the OADV-7 genome [ 4, 38], but instead contains various internal tandem repeats of varying length (25–71 bp). It is important to note, that this repeat region of BAdV-7 could be a result of de novo or reference assembly errors. Isolation of BAdV-7 has previously been restricted to primary bovine testicular cells, and bovine and ovine primary nasal turbinate cells [ 4, 15]. We have extended this list of susceptible cells by isolating BAdV-7 in KOP-R cells, a finite bovine eosophagus cell line with readily detected CPE on day three-post-infection. Several bacterial species were cultured from spleen and liver tissue of this animal but apart from Listeria monocytogenes, the other bacterial isolates were considered likely to be contaminants and not related to the observed pathology. The S427/18 strain also has an insertion of 17 bp when compared to the other three published BAdV-7 strains and a deletion of 76 bp which is unique to this BadV-7 strain. Given the paucity of avaliable BAdV-7 strains for use in in vitro and in vivo studies, we attempted to isolate virus by overlay of homogenized and filtered liver tissue onto KOP-R and MDBK cells. In addition to the intestine, adenoviral inclusions were observed in many other organs and were associated with necrosis in the liver, spleen, and other lymphoid organs throughout the body suggesting a systemic disseminated infection. In the current case, autolytic changes precluded a definite assessment of histologic lesions within the gastrointestinal tract, but viral inclusions were observed in cells with an endothelial morphology in the lamina propria of the intestine. Frozen spleen and liver tissue (200 mg) obtained at necropsy was homogenized in 500 µl PBS using ceramic beads in a FastPrep-24 5G homogenizer (MP Biomedical) and centrifuged at 12,000 RPM. 140 µl of tissue supernatant was used for automated RNA isolation using the QIAamp Viral RNA Mini Kit for the Qiacube (Qiagen) according to manufacturer’s instructions. In the liver, moderate amounts of Listeria monocytogenes and low amounts of Bacillus spp. Phylogenetic analysis of available genome sequences of BAdV-7 showed that the newly identified strain groups most closely with a recent BAdV-7 strain, SD18-74, from the USA, confirming that this newly identified strain is a member of the Atadenovirus genus. Virus titers were determined by performing TCID50 end-point dilution assays in triplicate using tenfold serial dilutions from (10−1 to 10−11) with TCID50/mL calculated using the Spearman and Kärber method [ 23]. Bovine adenovirus 7 (BAdV-7) is an unclassified member of the genus Atadenovirus with a worldwide distribution and has been reported to induce clinical disease of varying severity in infected cattle, ranging from asymptomatic infections to severe enteric or respiratory disease.