Termination of pregnancy in mice following administration of antibodies to the pentadecapeptide 10-24 of chicken riboflavin carrier protein: identification of a bioneutralizing epitope of chicken riboflavin carrier protein.

Our studies have shown that the administration of antibodies to chicken riboflavin carrier protein (cRCP) or disulfide-reduced carboxymethylated cRCP (RCM-RCP) leads to termination of pregnancy in mice. In an attempt to delineate the bioneutralizing epitopes, a combination of chemical modification and predictive methods was used. The results led to the identification of the region 10-24 of cRCP as a potential candidate. A single injection of antipeptide antibodies to pregnant mice on day 11 resulted in 100% pregnancy termination. This was accompanied by a drastic reduction in circulatory progesterone as early as 24 h after the antibody administration. These results thus demonstrate that the amino acid sequence 10-24 of cRCP harbours a bioneutralizing epitope of cRCP.