Chlamydiaceae Species Research Articles

Protein signatures distinctive of chlamydial species: horizontal transfers of cell wall biosynthesis genes glmU from archaea to chlamydiae and murA between chlamydiae and Streptomyces.

Chlamydiae are major human and animal pathogens. Based on alignments of different protein sequences, a number of conserved indels (insertion/deletions) were identified that appear to be unique and distinctive characteristics of the chlamydial species. The identified signatures include one 16 aa and two single aa inserts in the enzyme UDP-N-acetylglucosamine 1-carboxyvinyltransferase (MurA), a 1 aa insert in protein synthesis elongation factor P (EF-P), a 1 aa insert in the Mg(2+) transport protein (MgtE), a 1 aa insert in the carboxy-terminal protease and a 1 aa deletion in the tRNA (guanine-N(1)-)-methyltransferase (TrmD) protein. The homologues of these proteins are found in all major groups of bacteria and the observed indels are present in all available chlamydial sequences but not in any other species (except for the large insert in MurA in Streptomyces). The validity of three of these signatures (MurA, EF-P and MgtE) was tested by PCR amplifying the signature regions from several chlamydial species for which no sequence information was available. All Chlamydiaceae species for which specific fragments could be amplified (Chlamydia suis, Chlamydophila abortus, Chlamydophila psittaci, Chlamydophila felis) contained the expected signatures. Additionally, a fragment of the murA gene from Waddlia chondrophila and the efp gene from Simkania negevensis, two chlamydia-like species, were also cloned and sequenced. The presence of respective indels in these species provides strong evidence that they are specifically related to the traditional chlamydial species, and that these signatures may be distinctive of the entire Chlamydiales order. A 17 aa conserved indel was also identified in the cell wall biosynthesis enzyme UDP-N-acetylglucosamine pyrophosphorylase (GlmU), which is shared by all archaeal and chlamydial homologues. The gene for this protein is indicated to have been horizontally transferred from an archaeon to a common ancestor of the chlamydiae. The results also support a lateral transfer of the murA gene between chlamydiae and STREPTOMYCES: The large inserts in these peptidoglycan synthesis related genes in chlamydiae could account for their unusual cell-wall characteristics. These signatures are also potentially useful for screening of the chlamydiae species.

Aerosolized prostacyclin in acute respiratory distress syndrome caused by Chlamydiaceae spp. pneumonia

Management of respiratory failure in acute respiratory distress syndrome (ARDS) typically requires ventilatory assistance. If traditional approaches to mechanical ventilation and adjunctive measures fail to succeed in achieving adequate oxygenation, alternative measures should be considered. We describe an ARDS patient with respiratory failure caused by a severe Chlamydiaceae species community-acquired pneumonia (CAP). Aerosolized prostacyclin (PGI2) treatment was successfully instituted for refractory hypoxemia.

Chlamydia and Chlamydiales: more than meets the eye

This review summarizes the dramatic changes that have occurred in the taxonomy of bacteria known as Chlamydia. Best known for the diseases they cause in humans, these intracellular bacteria also comprise many species that are responsible for a wide variety of clinically and economically important diseases in livestock and companion animals. The old taxonomy grouped most of these species into C. psittaci because systematic methods for routinely distinguishing them were not available. DNA-based testing methods are now available that distinguish different chlamydial families, genera, and species. This summary reviews these tests and a number of oligonucleotide primers that distinguish these groups using PCR and PCR-RFLP. DNA-based methods are also being used to discover new families of chlamydia-like bacteria, at least one of which is responsible for abortion in cattle ( Waddlia chondrophila). This review summarizes the pathogenic roles of the Chlamydiaceae, new families, and individual species within the order Chlamydiales. These discoveries create opportunities for veterinarians to carry out epidemiological studies of chlamydiae that previously were not possible.

Detection of sequence variation in PCR-amplified fragments of omp2 gene from three species of the family Chlamydiaceae using agarose gel electrophoresis containing bisbenzimide-PEG

A simple technique providing a means for rapid genetic differentiation of chlamydial strains is described. The technique is based on a single-step sequence-specific separation of PCR-amplified DNA fragments by electrophoresis in an agarose gel containing a DNA ligand – bisbenzimide-PEG. A hypervariable region at the 5′ end of the omp2 gene of Chlamydiaceae species encoding the 60-kDa cysteine-rich outer membrane protein was selected as a target for PCR. The appropriate fragments were amplified from strains of Chlamydia trachomatis, Chlamydophila pneumoniae, and Chlamydophila psittaci, and the PCR products originating from different species were electrophoretically separated in the presence of the DNA ligand. We therefore demonstrated that PCR with a single pair of primers followed by simple agarose gel electrophoresis with bisbenzimide-PEG can be applied to the differentiation of three members of the family Chlamydiaceae which are commonly recognized as human pathogens.

Detection of sequence variation in PCR-amplified fragments of omp2 gene from three species of the family Chlamydiaceae using agarose gel electrophoresis containing bisbenzimide-PEG.

A simple technique providing a means for rapid genetic differentiation of chlamydial strains is described. The technique is based on a single-step sequence-specific separation of PCR-amplified DNA fragments by electrophoresis in an agarose gel containing a DNA ligand - bisbenzimide-PEG. A hypervariable region at the 5' end of the omp2 gene of Chlamydiaceae species encoding the 60-kDa cysteine-rich outer membrane protein was selected as a target for PCR. The appropriate fragments were amplified from strains of Chlamydia trachomatis, Chlamydophila pneumoniae, and Chlamydophila psittaci, and the PCR products originating from different species were electrophoretically separated in the presence of the DNA ligand. We therefore demonstrated that PCR with a single pair of primers followed by simple agarose gel electrophoresis with bisbenzimide-PEG can be applied to the differentiation of three members of the family Chlamydiaceae which are commonly recognized as human pathogens.