Background: The Group B Streptococcus (GBS) Surface Immunogenic Protein (SIP) is highly conserved and is present in all serotypes. An analysis of the primary protein structure determined that contains a secretion signal peptide and a LysM domain that allows it to anchoring to the cell wall by binding to glycan peptide, locating itself on the cell surface along with other proteins characterized as virulence factors in adhesion or invasion.
The biological function of the SIP is still unknown, so a mutagenesis strategy aimed at deleting the sip complete gene, it will allow us analyze the role the SIP in the pathogenesis of GBS.
Methods: A high-throughput suicide vector (pMBsacB) to generate a clean deletion of specific locus was used for deleting the sip gene from GBS strain. Then, the properties of adhesion and invasion in the cervical epithelium cell line (HeLa) was evaluated with the new GBS strain without SIP expression.
Results: We generate a new GBS strain without SIP expression. The sip gene deletion was complete, it was analyzed by DNA chromosomal massive sequencing. In addition, a decrease in adhesion properties was observed and Cell invasion capacity did not show significant differences for the new mutant of GBS strain.
Conclusions: The null expression the SIP in GBS strain affects adhesion phenotype in vitro, which suggests to SIP as new adhesin of GBS.