Chlamydophila
Encyclopedia
Chlamydophila is a bacteria
l genus
belonging to the family Chlamydiaceae
, order Chlamydiales
, class/phylum Chlamydiae
.
. All Chlamydiae
have a biphasic developmental lifecycle that depends on obligately intracellular growth in eukaryotic host cells.
Prior to 1999, criteria for chlamydial species were not exclusive. For example, at that time genus Chlamydia = family Chlamydiaceae; C. psittaci were distinguished from C. trachomatis by sulfadiazine
resistance, although not all C. psittaci were resistant; C. pneumoniae was classified by its appearance under electron microscopy (EM) and its ability to infect humans, although the EM appearance was found to differ from one research group to the next, and all of these species infected humans.
The systematic taxonomy
established for Chlamydiae in 1999 uses up-to-date, prevailing criteria for bacterial classification, including DNA-DNA reassociation, 16S and 23S ribosomal RNA
gene similarity, sequence similarity clustering of protein
coding genes, and genome
size. Supporting criteria such as antigen
detection, glycogen
staining, host association, and EM morphology are also employed, depending on applicability and availability. In 1999, many Chlamydia strains were reorganized into the genus Chlamydophila.
DNA-DNA reassociation similarity distinguishing Chlamydophila from Chlamydia is 10.1% (95% confidence interval
= 6.8 through 13.5), an accepted value for genus separation.
Divergence of Chlamydophila from Chlamydia is indicated by sequence similarity clustering of protein coding and ribosomal RNA genes. The 16S ribosomal RNA gene sequences of Chlamydophila and Chlamydia are close to 95% identical. However, 95% is not a cutoff for separating Chlamydiaceae genera but is a guideline for establishing new genera in chlamydial families. The full-length 23S rRNA genes of Chlamydophila and Chlamydia species are less than 95% identical.
Species in Chlamydophila include:
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
belonging to the family Chlamydiaceae
Chlamydiaceae
Chlamydiaceae is a family of bacteria that belongs to the Phylum Chlamydiae, Order Chlamydiales. All Chlamydiaceae species are Gram-negative and express the family-specific lipopolysaccharide epitope αKdo--αKdo--αKdo . Chlamydiaceae ribosomal RNA genes all have at least 90% DNA sequence identity...
, order Chlamydiales
Chlamydiales
The bacterial order Chlamydiales includes only obligately intracellular bacteria that have a chlamydia-like developmental cycle of replication and at least 80% 16S rRNA or 23S rRNA gene sequence identity with other members of Chlamydiales. Chlamydiales live in animals, insects, and protozoa...
, class/phylum Chlamydiae
Chlamydiae
Chlamydiae is a bacterial phylum and class whose members are obligate intracellular pathogens. Many Chlamydiae coexist in an asymptomatic state within specific hosts, and it is widely believed that these hosts provide a natural reservoir for these species....
.
Taxonomy
Chlamydophila was recognized in 1999, with six species in Chlamydophila and three in the original genus, ChlamydiaChlamydia (bacterium)
Chlamydia is a genus of bacteria that are obligate intracellular parasites. Chlamydia infections are the most common bacterial sexually transmitted infections in humans and are the leading cause of infectious blindness worldwide....
. All Chlamydiae
Chlamydiae
Chlamydiae is a bacterial phylum and class whose members are obligate intracellular pathogens. Many Chlamydiae coexist in an asymptomatic state within specific hosts, and it is widely believed that these hosts provide a natural reservoir for these species....
have a biphasic developmental lifecycle that depends on obligately intracellular growth in eukaryotic host cells.
Prior to 1999, criteria for chlamydial species were not exclusive. For example, at that time genus Chlamydia = family Chlamydiaceae; C. psittaci were distinguished from C. trachomatis by sulfadiazine
Sulfadiazine
Sulfadiazine is a sulfonamide antibiotic.-Uses:It eliminates bacteria that cause infections by stopping the production of folic acid inside the bacterial cell, and is commonly used to treat urinary tract infections ....
resistance, although not all C. psittaci were resistant; C. pneumoniae was classified by its appearance under electron microscopy (EM) and its ability to infect humans, although the EM appearance was found to differ from one research group to the next, and all of these species infected humans.
The systematic taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
established for Chlamydiae in 1999 uses up-to-date, prevailing criteria for bacterial classification, including DNA-DNA reassociation, 16S and 23S ribosomal RNA
Ribosomal RNA
Ribosomal ribonucleic acid is the RNA component of the ribosome, the enzyme that is the site of protein synthesis in all living cells. Ribosomal RNA provides a mechanism for decoding mRNA into amino acids and interacts with tRNAs during translation by providing peptidyl transferase activity...
gene similarity, sequence similarity clustering of protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
coding genes, and genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
size. Supporting criteria such as antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
detection, glycogen
Glycogen
Glycogen is a molecule that serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue...
staining, host association, and EM morphology are also employed, depending on applicability and availability. In 1999, many Chlamydia strains were reorganized into the genus Chlamydophila.
Chlamydophila differentiation
The meanMean
In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....
DNA-DNA reassociation similarity distinguishing Chlamydophila from Chlamydia is 10.1% (95% confidence interval
Confidence interval
In statistics, a confidence interval is a particular kind of interval estimate of a population parameter and is used to indicate the reliability of an estimate. It is an observed interval , in principle different from sample to sample, that frequently includes the parameter of interest, if the...
= 6.8 through 13.5), an accepted value for genus separation.
Divergence of Chlamydophila from Chlamydia is indicated by sequence similarity clustering of protein coding and ribosomal RNA genes. The 16S ribosomal RNA gene sequences of Chlamydophila and Chlamydia are close to 95% identical. However, 95% is not a cutoff for separating Chlamydiaceae genera but is a guideline for establishing new genera in chlamydial families. The full-length 23S rRNA genes of Chlamydophila and Chlamydia species are less than 95% identical.
| Genus | Approximate Genome Size (million DNA base pairs) | Detectable Glycogen | Number of Ribosomal Operons |
|---|---|---|---|
| Chlamydophila | 1.2 | No | 1 |
| Chlamydia | 1.0 | Yes | 2 |
Species
Distinctions such as EM morphology, antibiotic resistance, and extrachromosomal plasmid are typically species-specific characteristics.Species in Chlamydophila include:
- Chlamydophila pneumoniaeChlamydophila pneumoniaeChlamydophila pneumoniae is a species of Chlamydophila, an obligate intracellular bacteria that infects humans and is a major cause of pneumonia....
- Chlamydophila pecorumChlamydophila pecorumChlamydophila pecorum is a species of Chlamydiaceae that has been isolated only from mammals: cattle, sheep and goats , koalas , and swine. C. pecorum strains are serologically and pathogenically diverse....
- Chlamydophila felisChlamydophila felisChlamydophila felis is a bacterium endemic among house cats worldwide, primarily causing inflammation of feline conjunctiva, rhinitis and respiratory problems. C. felis can be recovered from the stomach and reproductive tract. Zoonotic infection of humans with C. felis has been reported...
- Chlamydophila psittaciChlamydophila psittaciChlamydophila psittaci is a lethal intracellular bacterial species that may cause endemic avian chlamydiosis, epizootic outbreaks in mammals, and respiratory psittacosis in humans. Chlamydophila psittaci is transmitted by inhalation, contact or ingestion among birds and to mammals...
- Chlamydophila abortusChlamydophila abortusChlamydophila abortus is a species in Chlamydiae that causes abortion and fetal death in mammals, including humans. Chlamydophila abortus was previously classified as Chlamydia psittaci along with all Chlamydiae except Chlamydia trachomatis. This was based on a lack of evident glycogen production...
- Chlamydophila caviaeChlamydophila caviaeChlamydophila caviae is a bacterium that can be recovered from the conjunctiva of Guinea pigs suffering from ocular inflammation and eye discharge. It is also possible to infect the genital tract of Guinea pigs with C. caviae and elicit a disease that is very similar to human Chlamydia trachomatis...
External links
- Chlamydophila genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
- Taxonomic Outline of the Procaryotes, Bergey's Manual of Systematic Bacteriology, Second Edition Release 1.0, April c. http://www.cme.msu.edu/Bergeys/april2001-genus.pdf