Extensive heterogeneity of the protein composition of Chlamydia trachomatis following serial passage in two different cell lines

Abstract

To determine if the host-modulated adherence characteristics of the intracellular bacterial pathogen Chlamydia fruhomatis were due to the acquisition of altered surface-exposed proteins, highly purified chlamydiae grown in two different host cells were analysed. Two serovars, L1 and E, were grown for multiple passages in both HeLa and McCoy host cells. Numerous protein differences in the chlamydial elementary bodies (EB) of each serovar grown in the two different hosts were detected by two-dimensional (2-D) gel electrophoresis and fluorography of radioactively labelled proteins. At least four to six serial passages in the alternative host were necessary before the changes were apparent. Iodination of suspensions of purified chlamydiae and 2-D electrophoresis revealed several surface proteins that were determined by the host cells in which the bacteria had replicated. These iodinated chlamydial proteins were removed by treatment of the iodinated EB with trypsin, indicating their location at the bacterial surface. Two of the major constituents of the outer-membrane complex, the cysteine-and methionine-rich 60 kDa and 40 kDa proteins, remained unchanged in both molecular mass and charge during the host adaptation. Several chlamydial proteins capable of binding iodinated host membrane preparations also exhibited hostdependent alterations. Immunoblotting experiments with a rabbit and a human polyclonal sera indicated that distinct host-specified chlamydial proteins were reactive with the two sera.

The role of lipopolysaccharide in the exposure of protective antigenic sites on the major outer membrane protein of Chlamydia trachomatis

“…The purity of the preparation was judged by SDS-PAGE in 12.5% (w/v) polyacrylamide gels. SDS-PAGE and Western blots were done as described by Goswami et al (1990). Fab fragments were obtained by trypsinization of the IgM mAb under reducing conditions (Bidlack & Mabie, 1986).…”