*2.3.3 CT621 and CT622*

Chlamydial cells use the type III secretion system to secrete CT621 and CT622 into the host cell cytoplasm [12, 15]. The presence of CT622 and CT621 in host cell cytoplasm should be involved in the pathogenetic mechanism of chlamydial infection, although their role needs to be further studied and elucidated. They seem to follow the same path but different kinetics in expression and secretion, meaning they play different roles in the survival and replication of the bacterium intracellularly [12].

#### *2.3.4 CT311*

Protein CT311 of *C. trachomatis* is secreted out of chlamydial inclusion into the cytosol of the infected cell and it enters host cell nucleus, thus it is a sufficient component for nuclear targeting [16]. The presence of this chlamydial component in the nucleus during the late stage of intracellular infection means that it can interact and modulate signal transduction pathways. This is an important tool to induce infection [16]. The

most possible role of CT311 is alteration of host cell mechanisms to facilitate exiting of host cell and spreading [16].
