The ongoing work of researchers at the University of Sassari within the LIFE Pinna project has led to new and important insights into the infection process of the protozoan Haplosporidium pinnae, which emerged during the project as the primary suspect in the mass mortality of Pinna nobilis. Initially, it was believed that the protozoan infected the digestive gland and completed its reproductive cycle there, ultimately killing the mollusk. However, throughout the project, thanks to hundreds of molecular analyses on the tissues of Pinna nobilis specimens intended for transplantation, UNISS was able to classify them into three distinct categories based on their sensitivity to the pathogen:  

• Highly sensitive individuals: even a mild mantle infection leads to death within a few days.  
• Less sensitive individuals: they survive the initial mantle infection but die within approximately 30 days when high infection rates affect all organs.  
• Resistant individuals: even with a latent presence of the protozoan in their tissues, these individuals remain generally healthy.  

In light of these findings, researchers in Sassari can now identify potential breeding individuals for reintroduction (restocking) efforts—selecting those with the highest chances of survival and resistance to potential infections by Haplosporidium pinnae. Beyond assessing pathogen infections, these analyses are crucial for the success of the project’s initiatives. In the coming months, researchers at the University of Sassari will also investigate whether there is a method to reduce infection levels in individuals kept in aquariums.

Credit: Ilenia Azzena, Ilaria Deplano, Chiara Locci/UNISS