Pathogenicity difference analysis of novel duck reovirus NY01 between in semi-muscovy duck and shelduck.

Recently, the waterfowl industry of China has suffered significant economic losses due to the novel duck reovirus (NDRV), an emerging pathogen. Its characteristic pathological manifestations include marked splenomegaly with diffuse hemorrhagic necrosis, multi-organ congestion, and parenchymal cell degeneration. Clinically recovered ducks frequently exhibit persistent growth retardation syndrome. In this study, a wild-type strain of NDRV, designated NY01, was isolated and identified from clinical spleen samples using viral isolation and cultivation techniques. To evaluate its pathogenic potential, an animal infection model was established using one-day-old healthy semi-muscovy ducks and shelducks. A standardized viral inoculum dose (ELD50=10-4.5/0.2mL) was administered, followed by systematic monitoring of clinical symptoms, dynamic weight changes, and histopathological lesions. Sampling time points were set at 3, 5, 7 and 14 days of post-infection (dpi), with three ducks per group euthanized randomly at each time point for gross lesion observation and histopathological analysis (hematoxylin-eosin (HE) staining). Results demonstrated that viral replication was detectable in target organs (liver, spleen, and kidney) as early as 72 hours post-inoculation, accompanied by multifocal necrosis, perivascular inflammatory cell infiltration, and parenchymal apoptosis. Furthermore, NDRV exhibited significantly higher infectivity and pathogenicity in semi-muscovy ducks than in shelducks.