Chlamydia

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Chlamydia
DukeMedNews Chlamydia Escapes Defenses By Cloaking Itself with Lipids: "Chlamydia is an obligate intracellular parasite that prospers within a host cell by hijacking the cell's internal machinery to survive and replicate. The bacterium lives within the cell in a protective capsule known as an inclusion. Chlamydia has been implicated in sexually transmitted infections, atherosclerosis and some forms of pneumonia. To date, it has not been clearly understood how Chlamydia has evolved to evade the cell's internal intruder alert system.Duke University Medical Center microbiologists have discovered that the parasitic bacteria Chlamydia escapes cellular detection and destruction by cloaking itself in droplets of fat within the cell. The researchers said that their findings represent the first example of a bacterial pathogen "mimicking" such a structure, or organelle, within a cell.

– Duke University Medical Center microbiologists have discovered that the parasitic bacteria Chlamydia escapes cellular detection and destruction by cloaking itself in droplets of fat within the cell. The researchers said that their findings represent the first example of a bacterial pathogen "mimicking" such a structure, or organelle, within a cell.Not only do the findings suggest a novel mechanism of bacterial infection, but the new insights into Chlamydia's actions within infected cells provide rational targets for potential drugs to halt the spread of the bacteria, said the researchers. Chlamydia has been implicated in sexually transmitted infections, atherosclerosis and some forms of pneumonia.Chlamydia is an obligate intracellular parasite that prospers within a host cell by hijacking the cell's internal machinery to survive and replicate. The bacterium lives within the cell in a protective capsule known as an inclusion. To date, it has not been clearly understood how Chlamydia has evolved to evade the cell's internal intruder alert system."In our experiments, we found that Chlamydia recruits lipid droplets from within the cell and stimulates the production of new droplets, which cover the surface of the inclusion," explained Yadunanda Kumar, Ph.D., a post-doctoral fellow in Duke's Department of Molecular Genetics and Microbiology. "This action of surrounding itself with lipid droplets may represent an example of organelle mimicry, where the chlamydial inclusion is protected from the cell's defenses by being perceived by the cell as just another lipid droplet.When these cloaked inclusions were treated with agents known to inhibit the production of lipid droplets, the researchers were able to significantly reduce the ability of the bacterium to replicate."It has long been thought that lipid droplets within cells were just passive repositories of energy for the cells," said Duke microbiologist Raphael Valdivia, Ph.D., senior member of the research team. "But now we are learning that these structures appear to play important roles in lipid synthesis and transport of cholesterol throughout the cell, and cell signaling."When the researchers screened the chlamydial proteins in yeast cells, they found four specific proteins that appeared to recruit and spur the production of lipid droplets."Our findings provide evidence for a novel mechanism of organelle subversion where Chlamydia recruits lipid bodies and co-opts their function for survival," Valdivia said. "Chlamydia may exploit lipid droplets to acquire lipids, modulate inflammation or just for protection."If unchecked, the inclusion will continue to grow until it fills the entire cell, causing it to explode, releasing thousands of bacteria ready to infect adjacent cells."Not only do the findings suggest a novel mechanism of bacterial infection, but the new insights into Chlamydia's actions within infected cells provide rational targets for potential drugs to halt the spread of the bacteria, said the researchers."

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