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Sneathia amnii is a poorly characterized gram-negative anaerobe that commonly colonizes the vagina. It has been linked to many obstetric disorders, including preterm labor, preeclampsia, and chorioamnionitis. S. amnii lyses human red blood cells, and we aimed to identify the hemolysin. We identified two genes that appear to encode transporter and effector components of a two-partner secretion system. The putative effector, which we refer to as SaFHA, contains a domain with amino acid similarity to the filamentous hemagglutinin (FHA) of Bordetella pertussis and its predicted structure suggests it may form a transmembrane channel or pore. Thus, we hypothesized that SaFHA would be secreted by S. amnii and that it would play a role in hemoglobbin release. To test this, a portion of the gene encoding the SaFHA protein in S. amnii was expressed in E. coli and used as an immunogen in rabbits. Western analysis using anti-SaFHA revealed that the protein is secreted and localizes to the bacterial surface. Pre-treatment of S. amnii with anti-SaFHA blocked the hemolytic activity whereas antiserum against an irrelevant protein had no effect. We partially purified SaFHA from S. amnii using cation exchange chromatography and the partially purified protein mediated hemoglobin release from human RBC, supporting our hypothesis. Further characterization of SaFHA will help provide more insight on the virulence of S. amnii, and perhaps shed light on the etiology of Sneathia-associated vaginal conditions, as well as future treatment options.

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Medical Microbiology

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VCU Graduate Research Posters

Characterization of Protein Involved in Hemolysis Expressed by Sneathia amnii, a Pathogen of the Female Urogenital Tract