Construction of a susceptible cell model for decapod iridescent virus 1 (DIV1) infection

Decapod iridescent virus 1 (DIV1) poses a severe threat to the Macrobrachium rosenbergii aquaculture industry due to its broad host range and high mortality rate. However, the lack of a stable, susceptible cell line has impeded the study of its infection mechanisms. In this study, we established an in vitro infection model using an insect-derived cell line, determining the optimal virus-cell incubation time to be 6 h post-infection. Cytopathic effects, including cell rounding, granulation, and detachment, were observed in infected cells. Quantification by TCID₅₀ assay showed that the cell-cultured virus reached a titer of 10^-2.67 TCID₅₀ per 0.1 mL, confirming substantial infectivity. Artificial challenge experiments demonstrated that cell-cultured DIV1 retained high pathogenicity, causing dose-dependent mortality in M. rosenbergii. Histopathological and transmission electron microscopy analyses revealed severe hepatopancreatic damage and the presence of hexagonal viral particles in infected tissues. Moreover, we performed whole-genome sequencing of a DIV1 strain, revealing a double-stranded DNA genome of 165,567 bp with 34.58% GC content, encoding 176 predicted open reading frames. Phylogenetic analysis confirmed its classification within the genus Decapodiridovirus. This study provides a foundational cell model for DIV1 research, facilitating future studies on viral pathogenesis and the development of control strategies.