Purification and partial characterization of a type-specific antigen of Rickettsia tsutsugamushi

A type-specific antigen (54- to 56-kilodalton polypeptide) in the envelope of Rickettsia tsutsugamushi was purified from each of three prototype strains (Gilliam, Karp, and Kato) by a combination of mild anionic detergent treatment, gel filtration, and reverse-phase high-performance liquid chromatography. The purified antigens from the three strains were shown to have similar amino acid compositions: primarily aspartic acid, glutamic acid, and glycine, with lesser amounts of cysteine, methionine, and tyrosine. The N-terminal amino acid sequences of the antigens were 74.3% homologous among the three strains.