CD4 and chlamydia trachomatis infectious disease: In conclusion, the recruitment of specific T-cells, B-cells, and HLA-DR-positive cells to both the lower and upper reproductive compartments in koalas and the correlation between the CD4-positive cell number and gross pathology score in the female genital tract highlighted in this study represent a clear step forward when exploring the mechanisms behind koala chlamydial infection immunopathogenesis.