Similarity between the group B and A streptococcal C5a peptidase genes.

Group B streptococci (GBS) and group A streptococci (GAS) are known to have surface-associated peptidase activity which specifically cleaves C5a (C5a-ase), the primary chemotaxin for polymorphonuclear leukocytes. Amplification products were obtained from GBS genomic DNA template by using the polymerase chain reaction and primers corresponding to the C5a peptidase gene of GAS (scpA12). A restriction map of the GBS full-length amplified gene (scpB) was developed. The scpB restriction map was found to be highly similar to that of the analogous gene in GAS. A 50-bp deletion was located near the 5' end of scpB in a region where repeat sequences are found in scpA12. Hybridization experiments confirmed that other serotypes of GBS also carry an scpB-like gene. These results show that GBS contain a gene, scpB, which is very similar to that harbored by M12 GAS. The probability that scpB encodes the C5a-ase protein is discussed.