POLYCLONAL ANTIBODIES WITH PREDETERMINED SPECIFICITY AGAINST BOVINE ALPHA-S1-CASEIN - APPLICATION TO THE DETECTION OF BOVINE-MILK IN OVINE MILK AND CHEESE

Comparing the primary sequences of bovine and ovine milk proteins, som e short peptide fragments are cow-specific, in particular the 141-148 fragment of bovine alpha(s1)-casein, which is deleted in its ovine cou nterpart. The 140-149 peptide was chemically synthesized on a solid ph ase matrix and directly used as an immunogen to produce polyclonal mon ospecific antibodies in rabbits. These antibodies recognized this frag ment both on the peptidyl resin and in the native protein. They appear ed to be monospecific, since no antigen-antibody complex was formed wi th homologous ovine or caprine proteins. Subsequently, a competitive e nzyme-linked immunosorbent assay was successfully developed for the de tection of defined amounts of cows' milk in sheep's milk from 0.125 to 64 % (v/v) and in cheese from 0.5 to 25 % (v/v) that was not influenc ed by heat treatment of milk or the degree of ripening of cheese.