Identification of a novel angiogenin inhibitor 1 and its association with hyaluronidase of Streptococcus suis serotype 2

To characterize the role of hyaluronidase (Hyl) of Streptococcus suis serotype 2 (S. suis 2), the hylA gene that encodes Hyl was cloned, expressed and purified. A murine brain cDNA library was used to screen for interacting proteins of Hyl. Employing the yeast two-hybrid system, a novel murine ribonuclease, angiogenin inhibitor 1 (AI1), which shares 93% homology with porcine AI1, was shown to interact with Hyl in yeast. Through co-immunoprecipitation assays, the interaction between AI1 and Hyl was further confirmed. Transcription and translation products of the identified cDNA were detected in both normal cells and S. suis 2-infected cells. AI1 was found to localize mainly in the cytoplasm of 293T cells. These results suggested that the identified protein AI1 might be involved in the pathogenesis of meningitis through interaction with Hyl of S. suis 2.