Aquaculture America 2024

February 18 - 21, 2024

San Antonio, Texas

Vibrio aestuarianus CORRELATION WITH TISSUE LESIONS IN CULTIVATED OYSTERS Magallana gigas IN SARDINIA, ITALY: MOLECULAR AND IN SITU HYBRIDIZATION APPROACHES

Giuseppe Esposito*, Gianna Asara, Daniela Mandas, Fulvio Salati, Claudio Murgia, Marina Antonella Sanna, Marta Polinas, Rosanna Zobba, Giovanni Pietro Burrai, Alberto Alberti, Angelo Ruiu, Elisabetta Antuofermo

 

Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta.

Via Bologna 148, 10154, Turin, Italy.

*giuseppe.esposito@izsto.it

 



 Vibrio aestuarianus subsp. francensis has been identified as a pathogenic agent responsible for recurring mortality in adult Pacific cupped oysters (Magallana gigas) in several countries. However, studies attribute these mortalities to the interaction of environmental factors and pathogens. Little information available in the literature highlights the need to clarify the mechanisms of action of V. aestuarianus in M. gigas . The objective of this study was to apply an in situ hybridization (ISH) system (RNAscope®) to detect the presence of Vibrio spp. in M. gigas.

Twenty−eight oysters (M. gigas) were  manually collected during  a mortality event (October 2016−March 2017) from San  Teodoro lagoon , one of Sardinia’ s leading oyster culture facilities, with a water temperature  of  14°C. The collected samples were  investigated by molecular, histopathological, and in situ hybridization (ISH) techniques.

In 29% of the oysters , the mantle exhibited a moderate to severe, nodular to multifocal hemocytic inflammatory infiltrate  associated with a  concentration of  V. aestuarianus greater than 104 copies/µL in qPCR.  ISH demonstrated the presence of Vibrio spp.  in 78% of the subjects  associated with an inflammatory process in the mantle and gills, with  a stronger and diffuse signal in oysters displaying moderate to severe inflammation (r=0.66, p<0.05) ( Figure 1).  Our  results suggest that V aestuarianus is a major contributor to oysters mortality.