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Journal of Clinical Microbiology, June 2004, p. 2501-2507, Vol. 42, No. 6
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.6.2501-2507.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Department of Microbiology and Infectious Diseases, The Royal Women's Hospital, Carlton, Victoria,1 National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory,2 Centre for Disease Control, Darwin, Northern Territory, Australia3
Received 14 November 2003/ Returned for modification 22 December 2003/ Accepted 4 February 2004
Chlamydia trachomatis conjunctival samples collected over a 6-month period from individuals with clinical signs of trachoma and located in remote communities in the Australian Northern Territory were differentially characterized according to serovar and variants. The rationale was to gain an understanding of the epidemiology of an apparent increased prevalence of acute trachoma in areas thought to be less conducive to this disease. Characterization was performed through sequencing of a region of the omp1 gene spanning the four variable domains and encoding the major outer membrane protein. Nucleotide and deduced amino acid sequences were genotyped by using a BLAST similarity search and were examined by phylogenetic analyses to illustrate evolutionary relationships between the clinical and GenBank reference strains. The predominant genotype identified corresponded to that of serovar C (87.1%), followed by the genotype corresponding to serovar Ba (12.9%). All nucleotide and amino acid sequences exhibited minor levels of variation with respect to GenBank reference sequences. The omp1 nucleotide sequences of the clinical samples best aligned with those of the conjunctival C. trachomatis reference strains C/TW-3/OT and Ba/Apache-2. All clinical samples (of serovar C) exhibited four or five nucleotide changes compared with C/TW-3/OT, while all serovar Ba samples had one or two nucleotide differences from Ba/Apache-2. Phylogenetic analyses revealed close relationships between these Northern Territory chlamydial samples and the respective reference strains, although the high proportion of sequence variants suggests an evolutionarily distinct C. trachomatis population causing eye infections in Australia. Given that such genotypic information has gone unreported, these findings provide knowledge and a foundation for trachoma-associated C. trachomatis variants circulating in the Northern Territory.
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