Restricted replication of viral hemorrhagic septicemia virus (VHSV) in a birnavirus-carrier cell culture

Bacterial and viral co-infections in aquaculture under climate warming: co-evolutionary implications, diagnosis, and treatment

Climate change and the associated environmental temperature fluctuations are contributing to increases in the frequency and severity of disease outbreaks in both wild and farmed aquatic species. This has a significant impact on biodiversity and also puts global food production systems, such as aquaculture, at risk. Most infections are the result of complex interactions between multiple pathogens, and understanding these interactions and their co-evolutionary mechanisms is crucial for developing effective diagnosis and control strategies. In this review, we discuss current knowledge on bacteria-bacteria, virus-virus, and bacterial and viral co-infections in aquaculture as well as their co-evolution in the context of global warming. We also propose a framework and different novel methods (e.g. advanced molecular tools such as digital PCR and next-generation sequencing) to (1) precisely identify overlooked co-infections, (2) gain an understanding of the co-infection dynamics and mechanisms by knowing species interactions, and (3) facilitate the development multi-pathogen preventive measures such as polyvalent vaccines. As aquaculture disease outbreaks are forecasted to increase both due to the intensification of practices to meet the protein demand of the increasing global population and as a result of global warming, understanding and treating co-infections in aquatic species has important implications for global food security and the economy.

A Cell Membrane Fusion Assay for the Fish Pathogen Spring Viremia of Carp Virus (SVCV)

Fusion of the infected cell membranes is a characteristic effect of a wide number of viral infections. Spring viremia of carp virus (SVCV), a rhabdovirus causing disease in farmed carp, can induce membrane fusion of the infected cells by shifting the pH of the culture medium to slightly acidic. Membrane fusion leads to the formation of clusters of cell nuclei enclosed in a cell membrane, the so-called syncytia, that can be easily visualized by cell staining and light microscope inspection. In the present work, we report a protocol to induce syncytia formation in EPC cells infected with SVCV, where membrane fusion is triggered by a low-pH incubation step. Appearance of syncytia can be observed at 18 hours post infection. The syncytia formation assay described here may serve as an experimental platform to quantitate SVCV, to determine virus infectivity, and a useful tool to study virus entry into the cell as well as to test candidate antiviral compounds that could block the entry of SVCV into cells by inhibiting membrane fusion.