Conjugation between the peptide and the carrier protein may be carried out as described by J. H. Kennedy et al. in Clinica Chimica Acta, Vol. 70, pages 1-31 (1976) with conjugating agents such as glutaraldehyde or a water soluble carbodiimide, e.g., 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (ECDI).