Characterization of DNA fragment from Chlamydia psittaci avian strain which shows high homology with hypB gene of Chlamydia.

A study was performed to characterize DNA fragment No. 17 of C. psittaci strain P-1041 which encoded 42 KD beta-galactosidase fusion protein with type-specific antigenicity. Sequence determination identified a partial open reading frame that spanned about 1,200b. p. nucleotides. Screening the literatures for the nucleotide and deduced amino acid sequences revealed extensive similarity between the DNA fragment of P-1041 and two chlamydial hypB genes. This DNA showed 91.5% homology with C. psittaci GPIC hypB gene in nucleotide sequence and 96.4% homology in deduced amino acid sequence. The hypB gene of C. trachomatis serovar A and the P-1041 DNA fragment showed 81.2% and 91.3% homology in nucleotide and amino acid sequences, respectively. Dot enzyme-linked immunosorbent assay, for the products of deleted DNA fragments defined the coding region for type-specific antigenic polypeptide. In addition, the P-1041 DNA fragment carried a sequence highly homologous (greater than 49%) with other bacterial and plant genes called chaperonin which responds to various stress in cells. From these results, the P-1041 DNA fragment was found to be a part of hypB gene and to encode the region critical for type-specific antigenicity.