First detection and genetic characterization of a novel duck reovirus in Vietnam based on the S1 segment

Duck reovirus (DRV), a member of the Orthoreovirus genus within the Reoviridae family, is associated with significant economic losses in the duck farming industry. This study aimed to detect the presence of DRV and genetically characterize the S1 gene segment of DRV strains identified on duck farms in Tien Giang Province, Vietnam. A total of 110 liver and spleen samples were collected from ducks exhibiting clinical signs suggestive of DRV infection. Reverse transcription-polymerase chain reaction was used to detect DRV. Positive samples were subjectied to phylogenetic and pairwise distance analyses based on the S1 gene sequence to determine genetic relatedness. The overall incidence of DRV infection was 14.54% (16/110), with a statistically significant association observed between infection rate and duck age (p < 0.05). Notably, ducks aged less than 4 weeks were 7.4 times more likely to be infected with DRV compared with those older than 6 weeks (95% confidence interval, 1.49–36.68; p = 0.01). Phylogenetic analysis revealed that the detected strain, designated CTU/NDRV/TG2024 (GenBank Accession No. PV034365), is closely related to novel DRV (NDRV) strains, sharing 94.48%–96.69% nucleotide identity. These findings confirm the circulation of an NDRV strain in Tien Giang Province, representing the first documented occurrence of DRV in the Mekong Delta region of Vietnam.