N-terminal anchor in surface immunogenic protein of Streptococcus agalactiae and its influence on immunity elicitation.

A multiplex PCR method was developed to characterize the potential variability within the sip gene from bovine isolates of Streptococcus agalactiae. An incomplete sip gene (ncosip) was found in four isolates of S. agalactiae. According to the in silico analysis of the missing region at amino acid level, the N-terminal of surface immunogenic protein (Sip) was found to contain a LysM domain motif; whilst the incomplete Sip (NcoSip) lacked a part of this motif. Immunity elicitation against Sip was confirmed by immunization of mice. This response was partially observed also with NcoSip.