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ARS Home » Research » Publications at this Location » Publication #98030
Title: DISTINGUISHING CHLAMYDIA AND "PARACHLAMYDIA" BY ELECTRONMICROGRAPHY AND ANALYSIS OF 23S RRNA (POSTER PRESENT FOR 99TH ASM MTG., MAY 30-JUNE 3, 1999)

Author
item EVERETT, KARIN - USDA-ARS-NADC, AMES, IA
item BUSH, ROBIN - UNIV. CALIF., IRVINE, CA
item AMANN, R - INSTIT., KOBLENZ, GERMANY
item MULLER, K -D - INSTIT. GHS, ESSEN, GE
item MICHEL, R - INSTIT., KOBLENZ, GERMANY

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 2/22/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: For 30 years, the order Chlamydiales has included only a single family of obligately, intracellular bacteria, the Chlamydiaceae. Phylogenetic analysis of 16S rRNA sequence data has recently shown that a new group of bacteria, "Parachlamydia acanthamoebae" candidatus, is related to Chlamydia. Both groups are also associated with disease in humans. Phenotypic and genetic evidence for relatedness or dissimilarity are critical determinants in bacterial classification. To find additional characteristics that would reveal the relationships between Chlamydia and "Parachlamydia," these bacteria were examined by electronmicroscopy. Like Chlamydia, "Parachlamydia" replicated in endocytic vacuoles and had two morphological forms, a large replicative form and an electron dense form, that were 0.6-1.0 um in diameter. This finding indicated that the morphology and possibly the replicative cycle of these bacteria were similar to those of Chlamydia. We also examined the full-length sequence of the 23S rRNA gene from a dozen strains of Chlamydia and compared them with the 23S rRNA sequence for "Parachlamydia." Parsimony analysis showed that the "Parachlamydia" 23S rRNA was more closely related to Chlamydia (17-19% different) than to other bacteria. It was concluded that these bacteria had similar developmental morphology and so could be grouped together in one order. The 23S rRNA differences were in the range of order and family separations among bacteria, and it was concluded that "Parachlamydia" should probably be a separate family in the order Chlamydiales.