Isolation and genetic characterization of canine adenovirus type 2 from a domestic dog showing neurological symptoms

Abstract

Canine adenoviruses (CAVs) are of two types: canine adenovirus type 1 (CAV-1), which causes infectious canine hepatitis, and canine adenovirus type 2 (CAV-2), which is mainly associated with the respiratory type of disease in dogs. Due to the widespread use of modified live vaccines to control canine adenoviral infections and subsequently reduced disease incidence, CAVs are often neglected by clinicians. Although a number of studies are available about CAV-1 prevalence in India, only meagre information is available about CAV-2. This study reports the CAV-2 infection in a vaccinated dog with neurological and respiratory symptoms which was found negative for other canine pathogens like canine distemper virus and canine parvovirus. The virus was successfully isolated from rectal swab in MDCK cells and characterized by immunofluorescence assay and virus neutralization test. On phylogenetic analysis of partial E3 region, the Indian CAV-2 grouped in a separate clade different from established subgroups. An insertion of “G” nucleotide was reported at nucleotide (nt.) position 1077 in the E3 gene of Indian CAV-2 isolates which led to a frameshift in the coding region of E3 gene thereby imparting additional eleven amino acids to its C-terminal end in comparison to isolates from other parts of the world. This may have an implication on the functional role of E3 protein inside the cell. This study reinforces the unique signature insertion in the E3 gene of Indian CAV-2 and is the second study in the world to report the association of CAV-2 with neurological disease in dogs.

Genetic characterisation of canine adenovirus type 1 in an 18‐month‐old mixed breed male dog and its effect on clinico‐pathology, hemato‐biochemistry and serum oxidant–antioxidant status

“…position 1380 in the E3 gene (ORFA), which was also reported in an Indian isolate (GQ340423). E3 protein of CAdV‐1 is pivotal for modulating the host response to infection 34,35 . So, further investigation with complete genome sequences of E3 protein will give in‐depth insight into host–virus interactions and disease progression.…”

Genetic analysis of Canine adenovirus type 2 strains circulating in Turkey from past to present

“…Two different studies conducted in India pointed out some mutations have occurred in the genome. One of them detected insertion of a residue in the Indian CAV-2 strain that caused a frameshift, and the other one reported nine predominant mutations (Chander et al 2021;Raja et al 2021). Besides, in one study performed in red foxes in Italy, two genetically different CAV-2 strains were gathered from the same fox (in phylogenetic tree accession no: JX416841, JX416842) revealed the circulation of the different viral strains among the fox population (Balboni et al 2013).…”