A comprehensive molecular survey of viral pathogens associated with canine gastroenteritis

Abstract

Viral pathogens are the primary cause of canine gastroenteritis. However, few structured comprehensive studies on the viral etiology of canine gastroenteritis have been conducted. In this study, 475 rectal swabs collected over three years (2018-2021) from clinical canine gastroenteritis cases were screened for the presence of six major enteric viruses - canine parvovirus 2 (CPV-2), canine distemper virus (CDV), canine adenovirus 2 (CAdV-2), canine coronavirus (CCoV), canine astrovirus (CaAstV), and canine rotavirus (CRV) - by real-time PCR. The most frequently detected virus was CPV-2, which was present in 64.8% of the samples (subtype 2a, 21.1%; 2b, 77.4%; 2c, 1.5%), followed by CDV (8%), CaAstV (7.2%), CCoV (5.9%), and CAdV-2 (4.6%). Two to four of these viruses in different combinations were found in 16.8% of the samples, and CRV was not detected. The complete genome sequences of Indian isolates of CDV, CCoV, and CaAstV were determined for the first time, and phylogenetic analysis was performed. This study highlights the need for routine prophylactic vaccination with the appropriate vaccines. Notably, 70.3% of animals vaccinated with DHPPiL were found to be positive for at least one virus. Hence, regular molecular analysis of the prevalent viruses is crucial for addressing vaccination failures.

Fig. 1

Prevalence of canine enteric viruses. (a) The prevalence of different canine enteric viruses during the years 2018-21 in the Hyderabad region of Telangana state in India. The length of the bar indicates the number of samples that tested positive (y-axis) for each virus either individually or in mixed infections (x-axis). The percentage above the bar indicates the prevalence of that particular virus. CPV* indicates CPV-2/2a/2b/2c. (b) The prevalence of antigenic variants of CPV-2 during the years 2018-21 in the Hyderabad region of Telangana state in India. The length of the bar indicates the number of samples that tested positive (y-axis) for the respective antigenic variant (x-axis). The percentage above the bar indicates the prevalence of that particular antigenic variant.

Fig. 2

Isolation of canine enteric viruses. Panel A shows images of an uninfected cell culture, and panel B shows images of a virus-infected cell culture, both taken at 20X (total of 200X) magnification. From left to right: (i) MDCK/CPV (ii) MDCK/CAdV-2, (iii) A-72/CCoV, (iv) B95a/CDV, (v) MDCK/CaAstV

Fig. 3

Phylogenetic analysis based on whole genome sequences of the isolates from this study and previously published sequences from the NCBI database. The CDV isolates from the current study clustered with members of the Asia 1 lineage (a). The CaAstV isolates from the current study clustered with members of group III, consisting of isolates from China and Brazil (b). The CCoV isolates from the current study clustered with members of group II, consisting of isolates from China and Taipei.