Isolation and Genetic Characterization of Virulence Factors in Adriatic Sturgeon ().

The first case of infection of in Adriatic sturgeon () was recently reported in a raceway system located in Northern Italy. A second episode of infection in sturgeons with absence of mortality and evident clinical signs, was registered in November 2020 in the same farm and is reported in this study. Histopathological changes observed in infected organs are described. The strains isolated in the two episodes were compared using molecular analysis based on PCR, phylogeny and virulence factors analysis. Not all the major virulence factors were detected for the two strains; in particular the strains 78697, isolated in November, lacks , compared to the strains 64844, isolated in September. Moreover, genetic variations were reported for and genes. These findings let us hypothesize a different virulence of the strains in accordance with clinical findings related to the sturgeons.