| Description: |
Chlamydia trachomatis infection is an important cause of preventable blindness and sexually transmitted disease (STD) in humans. There are 15 serovariants that exhibit distinct organotropism for the eye or the urogenital tract and are separated according to the pathobiotypes. Trachoma biovariants consist of serovars A, B, Ba, C, D, E, F, G, H, I, J and K. LGV (Lymphogranuloma venereum) biovariants consist of serovars L1, L2 and L3. Trachoma biovariants are noninvasive and epitheliotropic strains that cause blinding trachoma (A to C) or sexually transmitted diseases. LGV biovariants cause sexually transmitted diseases with disseminating infection of draining regional lymph nodes. The trpBA operon encoding tryptophan synthase is functional in STD serovars, whereas trpBA harbors mutations that inactivate the enzyme in ocular serovars. Chlamydia trachomatis is an obligate intracellular parasite depending on the host machinery for ATP synthesis. Chlamydial life cycle comprehends an intracellular metabolically- active "reticular body" and an inert extracellular spore-like "elementary body" equipped with a unique disulfide-cross-linked protein envelope.
Chlamydia trachomatis (strain A/HAR-13 / ATCC VR-571B) is an oculotropic strain derived from a clonal population originating from a single plaque-purified isolate. It harbors a chromosome and a plasmid. Even though the genomes of strains D/UW-3 and A/HAR-13 / ATCC VR-571B are 99.6% identical, they possess a number of important differences that may be involved in disease organotropism determination. A large in-frame deletion was found in the gene coding for Tarp. A 125bp deletion was found and was shown to be unique to oculotropic serovars. There are 8 interrupted ORFs in strain A/HAR-13 / ATCC VR-571B compared to strain D/UW-3. Whereas the strain D/UW-3 possesses 2 copies of tyrP, the second copy is disrupted in strain A/HAR-13 / ATCC VR-571B. A total of 3354 SNPs were identified between strain A/HAR-13 / ATCC VR-571B and strain D/UW-3. Nine SNPs are localized within RNA encoding regions, 226 in intergenic regions and 3119 in coding regions. |
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