Horizontal transmission of white spot syndrome virus (wssv) from Procambarus clarkii to Eriocheir sinensis in polyculture systems: Infection characteristics, physiological responses, and ecological impacts

Although laboratory studies have confirmed horizontal transmission of white spot syndrome virus (WSSV) among decapod crustaceans, its transmission dynamics in practical aquaculture remains poorly understood. This study investigated WSSV transmission from infected Procambarus clarkii to Eriocheir sinensis in a simulated polyculture environment. A 15-day outdoor pond experiment (120 m²) was conducted by co-culturing WSSV-infected crayfish with healthy crabs. Our results demonstrated successful cross-species transmission, with highest viral loads in gills and muscle tissues. Female crabs showed significantly higher susceptibility to infection than males. Physiological analysis revealed elevated oxidative stress markers in infected crabs, including increased superoxide dismutase activity and malondialdehyde levels. Molecular analysis showed upregulation of immune-related genes (anti-lipopolysaccharide factors, crustin, prophenoloxidase) in gills and muscle, indicating innate immune activation. We observed distinct tissue-specific responses: in male muscle, viral replication was associated with Nrf2 pathway activation and autophagy suppression, while gills tissues exhibited apoptosis potentially limiting viral spread. Plankton community shifts were also documented, with increased diatom and ciliate abundance but decreased green and golden algae in WSSV-infected waters. This study provides direct evidence of WSSV transmission between economically important crustacean species under practical aquaculture conditions, highlighting the disease risks in polyculture systems and the need for strict carrier screening. • First confirmation that WSSV transmits from Procambarus clarkii to Eriocheir sinensis in a shrimp-crab polyculture pond. • In infected E. sinensis , WSSV copy number peaks in gill and muscle, with females more susceptible than males. • E. sinensis infected with WSSV exhibited strong oxidative stress and activation of the non-specific immune system. • WSSV significantly alters pond plankton community structure: diatoms and ciliates increase, green algae and golden algae decrease.