title: Determinants of trachoma endemicity using Chlamydia trachomatis ompA DNA sequencing.
abstract: A six-year prospective study of Chlamydia trachomatis infection and ocular disease in Tanzanian village children was conducted to identify the determinants of trachoma endemicity using sequencing of ompA. Overall, 749 conjunctival samples were obtained, with 176 children sampled in both 1989 and 1995. 31.1% (233/749) were positive by PCR-enzyme immunoassay, and 76% (176/233) of the positives were sequenced in variable domains (VD) 1 to 4 (22 children in both 1989 and 1995). Twenty-six ompA genotypes of serovar A, and 19 of B/Ba were identified, and only 20% of genotypes identified in 1995 matched those found in 1989. In particular, B/Ba genotypes exhibited a 15-base region in VD 2 with increased nucleotide substitution, and these types were associated with age and water availability. Homotypic infection and infection with multiple genotypes and high chlamydial load did predict subsequent severe trachoma (odds ratio (OR) = 10.14, 95% confidence interval (CI): 1.71, 60.23; OR = 6.40, 95% CI: 0.75, 54.41; OR = 6.74, 95% CI: 0.82, 55.38, respectively). And, multitypic infection was clustered with residence of village and associated with familial cattle ownership. In conclusion, high ompA polymorphism and the inability of some hosts to clear infection with the same ompA genotype suggest two distinct but converging mechanisms of endemic severe trachoma.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Johns Hopkins University, 720 Rutland Avenue, Baltimore, Maryland 21205, USA. yhhsieh@jhmi.edu
authors.forename: Y H
authors.initials: YH
authors.lastname: Hsieh
authors.forename: L D
authors.initials: LD
authors.lastname: Bobo
authors.forename: T C
authors.initials: TC
authors.lastname: Quinn
authors.forename: S K
authors.initials: SK
authors.lastname: West
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001483:Base Sequence; D002417:Cattle; D002648:Child; D002675:Child, Preschool; D002692:Chlamydia trachomatis / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D019353:Endemic Diseases; D005500:Follow-Up Studies; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D012423:Rural Health; D013636:Tanzania / Q000453:epidemiology; D014141:Trachoma / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; C078167:OMPA outer membrane proteins