Cloning of the gene for cell-surface protein antigen A from streptococcus sobrinus (serotype d)

Abstract A gene library of Strep. sobrinus B13N (serotype d ) chromosomal DNA was constructed in Escherichia coli , with the bacteriophage vector λL47,1. A recombinant phage, λMDSM49, containing a 15.5 kb DNA insert, directed the expression of a 210 kDa antigenic protein. The recombinant 210 kDa protein was shown by Western blot analysis to be identical with cell-surface protein antigen A (spaA) from a serotype g strain. However, the restriction patterns of a subclone plasmid, pMD51, from λMDSM49 differed from those of serotype g strain. The cell-surface protein antigen I II from serotype c Streptococcus mutans is a potential immunogen for vaccination against dental caries and corresponds to the spaA from serotype d and g strains. A recombinant clone, pDM51, will be a useful tool for serological and molecular biological studies. The recombinant spaA provides useful material for assessment of its diagnostic and immunogenic potential.