The Chlamydiales are important intracellular parasites which cause a wide spectrum of diseases in humans and animals (www.chlamydiae.com). Chlamydia trachomatis is responsible for the most common bacterial sexually transmitted disease and also leading cause of preventable blindness. Chlamydophila pneumoniae is the causative agent of several pneumonia-like respiratory diseases, and has been implicated in increased susceptibility to HIV and atherosclerosis. The Chlamydiales group is currently composed of at least 4 distinct families (viz. Chlamydiaceae, Simkaniaceae, Parachlamydiaceae and Waddliaceae) and they are characterized by a unique two-stage developmental cycle. While chlamydiae species are best known as human and animal pathogens, the recently described Parachlamydia species are also found to infect free-living amoebae. Free-living amoebae, which are important components of soil and water ecosystems, are increasingly recognized as vectors for human pathogens (www.chlamydiae.com). It is now recognized that the diversity of chlamydiae both in terms of their numbers as well as clinical involvement is presently significantly underestimated. The obligate intracellular nature of these pathogens also limits their genetic and biochemical investigation. This emphasizes the need for other approaches for their identification as well as genetic and biochemical investigations. Recent phylogenetic studies as well as a number of uniquely shared conserved indels strongly indicate that among bacteria, Verrucomicroiba are the closest free-living relatives of Chlamydiae. Thus, it is of much interest to investigate what unique biochemical or other physiological chraracteristics are shared between these two groups of bacteria. In recent years, the genomes of several chlamydiae species have been sequenced. This information is being used to determine novel chlamydiae-specific conserved indels and unique proteins which can serve as unique biomarkers for identification and characterization of these organisms.
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4. Laterally Transfered Genes and Proteins
5. Conserved Indels Uniquely Shared by Chlamydiae and Verrucomicrobium
Selected References :
Chlamydiae Website: http://www.chlamydiae.com
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Bacterial (Prokaryotic) Phylogeny Webpage (March 2006). http://www.bacterialphylogeny.com/index.html