Cloning and expression in Escherichia coli of a protective surface protein from type V group B streptococci

This report describes a trypsin-resistant laddering protein purified from a type V strain, a serotype of important emerging clinical significance. This protein is present in a majority of type V clinical strains, elicits protective antibody in an animal model, and is cross-reactive with the alpha C protein and R1. The gene encoding this protein has been cloned; preliminary nucleotide sequence analysis reveals significant homology, though not identity, with the alpha C protein gene. These data support the hypothesis that there exists a family of related but distinct GBS surface proteins which may play a role in immunity to GBS infection.