Antigenic modification of polypeptides

A process for preparing an antigen for provoking the formation, in the body of an animal, of antibodies to a protein which is not endogenous or immunogenic to said animal, said process comprising

• activating said protein, or a peptide having a sequence corresponding to as least part of the sequence of said protein, having a sulfhydryl group thereon by treatment with an activator of the structure ##STR45## where X represents a non-reacting group comprising substituted or unsubstituted phenyl or C.sub.1-10 alkylene moieties, or a combination thereof, or an amino acid chain, so as to cause reaction of the activator with such amino group, said carrier being biologically foreign to said animal and selected having size sufficient to elicit antibody response following the administration thereof into the body of said animal;
• and
• treating the resulting activated carrier with a hormone endogenous to said animal, non-hormonal polypeptide endogenous to said animal, non-hormonal polypeptide or a synthetic or natural fragment of either having a sulfhydryl group.

A process for preparing an antigen for provoking the formation, in the body of an animal of antibodies to a protein which is not endogenous or immunogenic to said animal, said process comprising

• activating under neutral or acid conditions a carrier not having a sulfhydryl group but having an amino group with an activator of the structure ##STR47## where X represents a non-reacting group comprising substituted or unsubstituted phenyl or C.sub.1-10 alkylene moieties, or a combination thereof, or an amino acid chain, so as to cause reaction of the actovator with such amino group, said carrier being biologically foreign to said animal and selected having a size sufficient to elicit antibody response following the administration thereof into the body of said animal;
• and
• treating the resulting activated carrier with said protein, or a peptide having a sequence corresponding to at least part of the sequence of said protein, said protein or said peptide having a sulfhydryl group.