The recombinant production of Gap4, a chimeric GapC plasmin binding protein comprising the entire amino acid sequence of the Streptococcus dysgalactiae GapC protein in addition to unique amino acid sequences from the Streptococcus parauberis and Streptococcus agalactiae GapC proteins, is described. Also described is the use of Gap4 chimeric GapC protein in vaccine compositions to prevent or treat streptococcal infections in general and mastitis in particular.