Effects of interferon gamma on Chlamydia trachomatis serovar A and L2 protein expression investigated by two-dimensional gel electrophoresis

Chlamydia trachomatis is an obligate intracellular bacterium causing human ocular and genital disease. The lymphokine interferon gamma (IFN-gamma) is an important immune effector exerting antimicrobial effects towards several intracellular parasites, the chlamydia included. IFN-gamma has been report ed to inhibit the chlamydial replication in vitro in part by depleting intr acellular levels of tryptophan in a dose-dependent manner. In addition, dow n-regulation of important immunogens has been described. These findings are extended in this paper, in which we are combining pulse labeling with [S-3 5]methionine and two-dimensional gel electrophoresis with immobilized pH gr adients in order to investigate changes in the protein expression of C. tra chomatis serovar A and L2 caused by treatment with IFN-gamma. In contrast t o what was observed in C. trachomatis L2, our results showed that, in C. tr achomatis A, down-regulations of the chlamydia major outer membrane protein and of several other proteins were detectable upon IFN-gamma treatment. in addition, we report the up-regulations of C. trachomatis A and L2 proteins with molecular masses of approximately 30 kDa and 40 kDa which may be part of an, as yet, uncharacterized chlamydial response to IFN-gamma treatment.