Genital Chlamydia trachomatis: understanding the roles of innate and adaptive immunity in vaccine research

Abstract

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted disease worldwide, and despite significant advances in chlamydial research, a prophylactic vaccine has yet to be developed. This Gram-negative obligate intracellular bacterium, which often causes asymptomatic infection, may cause pelvic inflammatory disease (PID), ectopic pregnancies, scarring of the fallopian tubes, miscarriage, and infertility when left untreated. In the genital tract, Chlamydia trachomatis infects primarily epithelial cells and requires Th1 immunity for optimal clearance. This review first focuses on the immune cells important in a chlamydial infection. Second, we summarize the research and challenges associated with developing a chlamydial vaccine that elicits a protective Th1-mediated immune response without inducing adverse immunopathologies.

FIG 1

(Top left) Laparoscopy surgical procedure showing a ruptured left fallopian tube as a result of ectopic pregnancy. The image shows the presence of significant hemoperitoneum. The patient was positive for Chlamydia trachomatis by PCR. (Top right) Fitz-Hugh-Curtis syndrome caused by Chlamydia trachomatis. (Bottom) Pelvic inflammatory disease (PID) caused by Chlamydia trachomatis infection of the uterus, fallopian tubes, and ovaries. The image shows the presence of a large dilation of the right fallopian tube, representing a tubo-ovarian abscess. (Inset) Drainage of the tubo-ovarian abscess.