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

海洋哺乳动物是海洋生态系统健康状况的指示物种，受到众多生物和非生物因素的威胁。在德国海岸，斑海豹（Phoca vitulina）最常见的疾病是呼吸道感染。phocae链球菌是与呼吸道感染相关的常见分离细菌病原体之一，其特征为革兰氏阳性、溶血、兼性厌氧、过氧化氢酶阴性和血清学异质性。其分子感染机制几乎是未知的。因此，我们的目标是在应用项目中表征从斑海豹中分离的不同S. phocae菌株的毒力相关特征，包括粘附、定植、生物膜形成、入侵和细胞毒性作用。调查将在两种用于研究呼吸道病原体的模型上进行：空气-液界面（ALI）培养和精确切割的海豹肺片（PCLS），这些肺片将从新鲜尸体上取样或由合作伙伴Ursula Siebert教授提供。这两种模型都包含高度分化的初级气道上皮细胞，使我们能够模拟自然条件，并在其自然储存库中研究病原体。此外，我们希望通过将表型与适当的基因型进行比较来确定病理类型。来自柏林的Marcus Fulde教授将提供不同的S. phocae菌株的基因组序列。本研究结果将有助于了解斑海豹肺上皮细胞感染的分子机制。作为一种新兴的野生动物病原体，这可能是重要的，即使其可能的人畜共患的潜力尚未明确。

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.