B-cell epitope mapping of human testis specific basic protein

Sesum from an immunologically infertile patient (ISA-I) was used in screening human testis cDNA expression library. A new testis--specific candidate antigen-- human testis specific basic protein (TSBP) was identified by this patient serum. DNA sequencing and homology searching in databases showed that TSBP is a new testis specific protein. Northern blot analyses showed that TSBP recognized a single message present only in testis. The fusion protein expressed in E. Colt was recognized by original serum ISA--I. A B cell epitope was identified in region of 11 amino acid residues near the carboxyterminus of the TSBP protein by unidirectional nested deletion method and Western blot analyses. A chimeric peptide containing the predicted epitope has been designed and synthesized.