Molecular Evidence of Group D Rotavirus in Commercial Broiler Chicks in India

Abstract

Group D rotavirus (RVD) is one of the evolving viral causes of acute gastroenteritis in avian species all over the world but its frequency in Indian poultry is not known. We report here the first sequence-confirmed RVD infection in 1–2 week old broiler chicks from northern India. Initial confirmation of type D rotavirus was done using polyacrylamide gel electrophoresis and VP6 gene based reverse-transcriptase-PCR (RT-PCR) for group D rotavirus, which produced a specific 742 bp amplicon in positive cases. The intestinal contents which showed presence of group D rotavirus strain were designated as RVD/Avian/India/PTN-14/2012/ GXP[X] and RVD/Avian/India/UKD-48/2012/GXP[X]. The comparative sequence analysis based on partial VP6 gene of type D rotavirus Indian strains revealed higher homology with the VP6 genes of the avian group D rotaviruses from Brazil, Germany, Netherlands, Bangladesh and UK, both at the nucleotide (87.2–89.6%) and amino acid (98.7–99.5%) levels. These two Indian avian RVD isolates clustered together, away from other Asian group D isolates from Bangladesh. The analysis of group specific VP6 protein showed amino acid changes at only two positions i.e. 228 and 384 when compared to the reference group D rotavirus strain (GenBank accession number: GU733448) confirming conserved nature of this protein. This seems to be the first sequence-confirmed detection of group D avian rotavirus in broiler chicks from India. The findings emphasise the importance of this virus in enteric infections of Indian poultry flocks. The study also emphasises the need for intensifying the epidemiological surveillance for group D rotaviruses in the near future.