Genetic Variability and Evolution of CsRV1 in Callinectes sapidus

In recent decades, there has been a significant increase in epizootic events in aquatic species. Moreover, a notable number of pathogens typically associated with human infections have been reported in these environments, some of which are causative agents of mortality in aquatic animals. This alarming trend underscores the urgent need for comprehensive research and mitigation strategies.
In this context, we present a study focused on Callinectes sapidus reovirus 1 (CsRV1), a pathogenic virus spreading along the Atlantic coast of the Americas that may influence the distribution of its host populations, the blue crab Callinectes sapidus. CsRV1 has a double-stranded RNA genome, organized into 12 segments, and is characterized by high mutation rates, segment recombination and reassortment.
Our study investigates the genetic variability of CsRV1, aiming to understand how it is evolving along the Atlantic coast of the Americas, its area of origin. To achieve this goal, we conducted phylodynamic reconstruction using all available genomes and segments from the NCBI Virus database. Molecular dating based on whole-genome data suggests that CsRV1 emerged approximately 40 years ago, with a notable increase in genetic diversity and viral population size occurring around a decade ago.
These results not only provide an overview of the genetic variability of CsRV1 in the Americas but may also prove valuable should the virus be detected in C. sapidus specimens from other geographic areas, given that its host is a highly invasive alien species. In this context, we are currently screening C. sapidus specimens, primarily collected from Sardinia, but also from other areas of the Mediterranean Sea.
Moreover, these findings underscore the importance of monitoring aquatic pathogens, particularly when invasive alien species such as C. sapidus may serve as vectors for previously undetected pathogens that pose potential threats to native species and local ecosystems.