Identification of Streptococcus phocae pathotypes by comparing virulence-associated traits of harbor seal isolates in primary airway epithelial cell models

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Marine mammals are indicator species for the health status of the marine ecosystem and threaten by numerous biotic and abiotic factors. At the German coast, the most common diseases in harbour seals (Phoca vitulina) are respiratory infections. Streptococcus phocae is one of the frequently isolated bacterial pathogen associated with those respiratory infections and characterized as gram-positive, beta-haemolytic, facultative anaerobic, catalase-negative and serologically heterogeneous. Its molecular infection mechanisms are nearly unknown. Thus, we aim within the applied project to characterize virulence-associated features including adherence, colonization, biofilm formation, invasion and cytotoxic effects of different S. phocae strains isolated from harbour seals. Investigations will be performed in two models that are used to study respiratory pathogens: air–liquid-interface (ALI) cultures and precision-cut lung slices (PCLS) of harbour seals that will be sampled from fresh carcasses or provided by the cooperation partner Prof. Prof. h.c. Dr. Ursula Siebert. Both models comprise highly differentiated primary airway epithelial cells and will allow us to mimicry natural conditions and to investigate a pathogen in its natural reservoir. In addition, we want to identify pathotypes by comparing the phenotypes with the appropriate genotypes. Genome sequences of a collection of different S. phocae strains will be provided by Prof. Dr. Marcus Fulde from Berlin. The outcome of this project will help to understand the molecular mechanisms that are involved in the infection of epithelial lung cells of harbour seals. As S. phocae being an emerging pathogen in wildlife this might be important, even as its possible zoonotic potential is not clarified yet.