<b><i>E3</i></b> Gene-Based Genetic Characterization of Canine Adenovirus-2 Isolated from Cases of Canine Gastroenteritis in India Revealed a Novel Group of the Virus

Abstract

Canine adenovirus (CAV) circulates as two distinct serotypes, CAV-1 and CAV-2, which are antigenically related but differ in their clinical manifestations. CAV is one of the important viral agents in the etiology of canine gastroenteritis. Here, we report the molecular surveillance and genetic characterization of CAV from clinical cases of canine gastroenteritis. A total of 302 fecal/rectal swabs were collected from dogs presented with gastroenteritis at various clinics in and around Hyderabad, India during 2018-19. These samples were tested for CAV using polymerase chain reaction with primers designed for the CAV E3 gene and the virus was isolated from positive samples. CAV-2 nucleic acid was present in 4.9% of the test samples. The partial sequence analyses of the E3 gene of the CAV-2 isolates revealed a frameshift mutation by insertion of nucleotide "G" at 1077 position of E3 gene, which resulted in an extension of the polypeptide chain by eleven amino acids. As a result, isolates from the current study formed a novel group, and the virus that was previously subdivided into two groups worldwide is now categorized under three. The study identifies a novel group of CAV-2 circulating in India providing an updated information regarding CAV-2.

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

“…2 a). These findings are in agreement with a recent study from India [ 9 ] and reinforce the unique signature “G” nt. insertion in E3 gene of Indian CAV-2 isolates.…”

“…After the introduction of live-modified vaccines and their widespread use to control disease, the incidence of canine adenoviral infections has reduced [ 20 ] and until a recent study [ 9 ], the prevalence of CAV-2 in the dog population in India was unreported. It is to mention that there are only a few reports of CAV-2-associated neurological disease of dogs and hence, the possibility of CAV-2 causing the nervous signs is ignored by the clinicians which could be the reason that CAV-2 remained unreported in the past.…”

“…Although CAV-2 is supposed to cause a transient and asymptomatic or mild form of respiratory disease and remains restricted to the upper respiratory tract causing laryngeotracheitis, in presence of other pathogens or in immune-compromised host, it has been reported to cause severe necrotising bronchitis and interstitial pneumonia [ 3 ]. CAV-2 is also associated with fatal cases of diarrhoea [ 8 , 9 ] and neurological disease in dogs [ 5 ]. With the widespread use of modified-live vaccines to protect dogs from infectious agents such as canine adenovirus, it is now being considered as a pathogen of less importance and is neglected by clinicians.…”

A Comprehensive Molecular Survey of Viral Pathogens Associated with Canine Gastroenteritis During 2018-21

“…Canine parvovirus (CPV) (Caddy 2018), Canine distemper virus (CDV) (Quintero-Gil et al 2019), Canine adenovirus (CAdV) (Ramidi et al 2020), Canine coronavirus (CCoV) (Buonavoglia et al 2006), Canine astrovirus (CaAstV) (Fauquet and Fargette 2005), Canine rotavirus (CRV) (Ortega et al 2017) were frequently reported as a cause for viral gastroenteritis in dogs. CPV belonging to Parvoviridae family is highly contagious and was rst identi ed in dogs suffering from severe hemorrhagic gastroenteritis and myocarditis as CPV-2 variant (Appel et al 1979;Hoang et al 2019); later on replaced by three antigenic variants namely CPV-2a, CPV-2b, and CPV-2c (Zhong et al 2014;Sharma et al 2016;Chiang et al 2016;Zhou et al 2017b).…”

“…It was reported that at least fteen different lineages of CDV are circulating worldwide (Bhatt et al 2019;Kodi et al 2020). CAdV belongs to Adenoviridae family and circulates as two distinct serotypes, CAdV-1 and CAdV-2 (Mohammadi et al 2011;Ramidi et al 2020). Despite routine vaccinations, re-emergence of CAdV-2 was documented throughout the world (Balboni et al 2014).…”