The invention provides a conjugate comprising an antigen and a carrier molecule, wherein the carrier molecule comprises a BP-2a antigen and a spb1 antigen. BP-2a and spb1 are Streptococcus agalactiae antigens. The conjugate may be used in a method for raising an immune response in a mammal, the method comprising administering the conjugate to the mammal. Also provided are pharmaceutical compositions, particularly vaccines, comprising the conjugate.