Yashpal Singh Malik, ICAR-Indian Veterinary Research Institute

Yashpal Singh Malik, Jobin Jose Kattoor, Pallavi Deol, and Shubhankar Sircar ICAR-Indian Veterinary Research Institute, Mukteshwar, Nainital 263138, Uttarakhand, India

Epidemiology, Evolution, and Diversity

Rotaviruses (RVs) are a major cause of enteritis and diarrhea in a wide range of mammalian and avian species, leading to significant global losses in livestock and poultry industries. While group A rotaviruses (RVA) have been extensively studied, the role of other avian rotavirus (AvRV) groups, such as RVD, RVF, and RVG, remains unclear. Among these, avian group D rotavirus (AvRVD) has emerged as a notable viral agent of acute gastroenteritis in avian species. This study was prompted by the lack of epidemiological research and the absence of rapid, sensitive diagnostic tools for detecting AvRVD in poultry. A VP6 gene-targeted RT-PCR assay was developed with high sensitivity (2.95×10⁻⁷ ng/μL = 1.49×10³ copies) compared to previously reported assays (5×10⁻⁴ ng/μL). Epidemiological investigations revealed a 29.05% prevalence of AvRVD (43/148) among layer chickens with enteritis symptoms. AvRVD was also detected in 6.04% (13/215) of intestinal samples across northern and southern Indian states. Genetic characterization of VP6 and NSP4 genes from selected isolates demonstrated high similarity to global strains. Phylogenetic analysis suggested independent evolution of these genes, with VP6 closely related to a Nigerian strain (NEI013A) and NSP4 to a Brazilian strain (RS 6). In-silico analysis identified three N-glycosylation sites in VP6 and a bicistronic coding sequence in NSP4. These findings highlight the prevalence of AvRVD in Indian poultry, the diagnostic utility of the developed assay, and the genetic uniqueness of Indian isolates. Continued research is essential to understand emerging rotavirus groups and mitigate threats to the poultry sector.