Identification and characterization of IgA1 protease from Streptococcus suis.

Streptococcus suis (S. suis) is a major swine pathogen and an emerging zoonotic agent. However, the current understanding of the S. suis pathogenesis of infection remains limited. In the present study, an IgA1 protease of S. suis was identified for the first time. The protein was recombinantly expressed in Escherichia coli, and the purified recombinant protein showed good cleaving reactivity to IgA1 and was highly immunoreactive to convalescent sera. The gene was found to exist in most pathogenic strains but scarcely in non-invasive isolates. These findings suggested that the IgA1 protease might play an important role in the pathogenesis of S. suis.