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Cloning and sequence analysis of the major outer membrane protein gene of Chlamydia psittaci 6BC
K D Everett1, A A Andersen, M Plaunt
1Department of Microbiology and Immunology, University of Tennessee, Memphis 38163.
Abstract:
The gene encoding the major outer membrane protein (MOMP) of the psittacine Chlamydia psittaci strain 6BC was cloned and sequenced. N-terminal protein sequencing of the mature MOMP indicated that it is posttranslationally processed at a site identical to the site previously identified in the MOMP of Chlamydia trachomatis L2. The nucleotide sequence of the C. psittaci 6BC MOMP gene was found to be 67 to 68% identical to those of human C. trachomatis strains, 73% identical to that of Chlamydia pneumoniae IOL-207, 79% identical to that of the C. psittaci guinea pig inclusion conjunctivitis strain, GPIC, and 83% identical to that of the C. psittaci ovine abortion strain S26/3. In contrast, the 6BC sequence was found to be greater than 99% identical to the sequences reported for two strains of C. psittaci, A22/M and Cal-10 meningopneumonitis, believed to be of nonpsittacine avian origin. Monoclonal antibody analysis confirmed the nonpsittacine avian origin of A22/M but identified the Cal-10 strain from which the MOMP gene was previously sequenced as a psittacine strain. These results confirm that psittacine and nonpsittacine avian strains of C. psittaci are closely related and distinct from the mammalian guinea pig inclusion conjunctivitis and ovine abortion strains of C. psittaci.
Insights
The major outer membrane protein (MOMP) gene of Chlamydia psittaci was sequenced, revealing close genetic relationships among avian strains. This study differentiates avian Chlamydia psittaci from mammalian strains.
Area of Science:
- Microbiology
- Genomics
- Veterinary Medicine
Background:
- Chlamydia psittaci is an important avian pathogen.
- The major outer membrane protein (MOMP) is a key virulence factor and target for classification.
- Understanding genetic diversity is crucial for disease control.
Purpose of the Study:
- To clone and sequence the MOMP gene from a psittacine Chlamydia psittaci strain (6BC).
- To compare the genetic relatedness of this strain to other Chlamydia species and strains.
- To investigate the evolutionary relationship between psittacine and nonpsittacine avian C. psittaci.
Main Methods:
- Gene cloning and nucleotide sequencing of the C. psittaci 6BC MOMP gene.
- N-terminal protein sequencing of the mature MOMP.
- Sequence comparison with MOMP genes from various Chlamydia strains (human, avian, mammalian).
- Monoclonal antibody analysis for strain origin confirmation.
Main Results:
- The C. psittaci 6BC MOMP gene sequence shows varying identity to other Chlamydia species (C. trachomatis, C. pneumoniae).
- High sequence identity (>99%) was found with nonpsittacine avian C. psittaci strains (A22/M, Cal-10).
- Monoclonal antibody analysis confirmed A22/M as nonpsittacine avian but identified Cal-10 as psittacine, contrary to previous assumptions.
Conclusions:
- Psittacine and nonpsittacine avian strains of C. psittaci are closely related genetically.
- Avian C. psittaci strains are distinct from mammalian strains (guinea pig inclusion conjunctivitis, ovine abortion).
- The MOMP gene sequence and antibody analysis are valuable tools for differentiating C. psittaci strains and understanding their origins.