Interaction of chlamydiae and host cells in vitro

Abstract

The obligately intracellular bacteria of the genus Chlamydia, which is only remotely related to other eubacterial genera, cause many diseases of humans, nonhuman mammals, and birds. Interaction of chlamydiae with host cells in vitro has been studied as a model of infection in natural hosts and as an example of the adaptation of an organism to an unusual environment, the inside of another living cell. Among the novel adaptations made by chlamydiae have been the substitution of disulfide-bond-cross-linked polypeptides for peptidoglycans and the use of host-generated nucleotide triphosphates as sources of metabolic energy. The effect of contact between chlamydiae and host cells in culture varies from no effect at all to rapid destruction of either chlamydiae or host cells. When successful infection occurs, it is usually followed by production of large numbers of progeny and destruction of host cells. However, host cells containing chlamydiae sometimes continue to divide, with or without overt signs of infection, and chlamydiae may persist indefinitely in cell cultures. Some of the many factors that influence the outcome of chlamydia-host cell interaction are kind of chlamydiae, kind of host cells, mode of chlamydial entry, nutritional adequacy of the culture medium, presence of antimicrobial agents, and presence of immune cells and soluble immune factors. General characteristics of chlamydial multiplication in cells of their natural hosts are reproduced in established cell lines, but reproduction in vitro of the subtle differences in chlamydial behavior responsible for the individuality of the different chlamydial diseases will require better in vitro models.

Insights Into Host Cell Cytokines in Chlamydia Infection

“…Intracellular infection starts with the entry of EBs into a host cell. Then, the endocytosed EBs differentiates into noninfectious but metabolically active RBs (6), which replicates and converts into EBs again for transmission of the infection to a new host cell (1). Invasion of the host by Chlamydia and the ensuing chlamydial life cycle, involves series of poorly understood mechanisms that compromise and interfere with the function of the host cells, thus damaging host health.…”

Chlamydial MreB Directs Cell Division and Peptidoglycan Synthesis in Escherichia coli in the Absence of FtsZ Activity

“…The molecular mechanism of cell division in the Chlamydia genus in the absence of FtsZ is poorly understood. Two models proposed for Chlamydia cell division are canonical binary fission (31,32) and polarized division (33). A subset of the members of Planctomycetes that lack FtsZ propagate by a budding-like mechanism (34).…”

Ocular Chlamydia trachomatis infection: elimination with mass drug administration

“…RBs replicate, by division, within the inclusion. The prevailing theory is that they divide by binary fission (6,7), however, studies have described polarized cell division similar to budding (8). RBs are converted back to EBs after several rounds of division; this process is delayed and asynchronous.…”