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DNA sequence polymorphism of the Chlamydia trachomatis omp1 gene
C L Yang1, I Maclean, R C Brunham
1Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.
Abstract:
The Chlamydia trachomatis major outer membrane protein gene (omp1) was amplified by polymerase chain reaction (PCR) from 89 clinical specimens, and restriction fragment length polymorphism (RFLP) patterns were analyzed after AluI or AluI and MspI digestion. Ten distinct RFLP omp1 genotypes were observed, although 4 types accounted for 70% of the isolates. The DNA sequence of variable domains (VDs) 1, 2, and 4 were determined for 49 samples. Thirty samples (61%) had prototype VD sequences, 15 (31%) had sequences that varied from prototype sequences, and 4 (8%) contained sequences from > 1 chlamydial isolates. Eleven of the 15 DNA sequence variations were one- or two-site nucleotide substitutions, 10 of which resulted in an amino acid change. Four DNA sequence variations were more extensive, with multiple nucleotide substitutions, insertions, or deletions. The data demonstrate that C. trachomatis isolates circulating in a relatively circumscribed geographic community exhibit remarkable omp1 DNA sequence polymorphism.
Insights
Chlamydia trachomatis outer membrane protein gene (omp1) shows significant DNA sequence polymorphism in clinical isolates. This genetic variation in omp1 is important for understanding Chlamydia trachomatis evolution and diagnostics.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Chlamydia trachomatis is a major cause of sexually transmitted infections.
- The major outer membrane protein (omp1) gene is a key target for Chlamydia trachomatis typing and vaccine development.
- Understanding genetic diversity within C. trachomatis is crucial for effective disease control.
Purpose of the Study:
- To investigate the genetic polymorphism of the Chlamydia trachomatis omp1 gene in clinical isolates.
- To characterize the diversity of omp1 genotypes and DNA sequences within a specific geographic community.
Main Methods:
- Amplification of the omp1 gene from 89 clinical specimens using polymerase chain reaction (PCR).
- Analysis of restriction fragment length polymorphism (RFLP) patterns after AluI or AluI and MspI digestion.
- Determination of DNA sequences for variable domains (VDs) 1, 2, and 4 in 49 samples.
Main Results:
- Ten distinct RFLP omp1 genotypes were identified, with 4 types comprising 70% of isolates.
- Significant DNA sequence variation was observed in VDs 1, 2, and 4, with 31% of samples showing deviations from prototype sequences.
- Multiple nucleotide substitutions, insertions, or deletions were found in some omp1 DNA sequences, indicating substantial genetic diversity.
Conclusions:
- Chlamydia trachomatis isolates from a defined geographic area exhibit considerable omp1 DNA sequence polymorphism.
- The observed genetic diversity highlights the dynamic nature of the C. trachomatis omp1 gene.
- This polymorphism may have implications for diagnostic accuracy and vaccine efficacy.