title: Chlamydia pneumoniae is genetically diverse in animals and appears to have crossed the host barrier to humans on (at least) two occasions.
abstract: Chlamydia pneumoniae is a common human and animal pathogen associated with a wide range of diseases. Since the first isolation of C. pneumoniae TWAR in 1965, all human isolates have been essentially clonal, providing little evolutionary insight. To address this gap, we investigated the genetic diversity of 30 isolates from diverse geographical locations, from both human and animal origin (amphibian, reptilian, equine and marsupial). Based on the level of variation that we observed at 23 discreet gene loci, it was clearly evident that the animal isolates were more diverse than the isolates of human origin. Furthermore, we show that C. pneumoniae isolates could be grouped into five major genotypes, A-E, with A, B, D and E genotypes linked by geographical location, whereas genotype C was found across multiple continents. Our evidence strongly supports two separate animal-to-human cross species transfer events in the evolutionary history of this pathogen. The C. pneumoniae human genotype identified in the USA, Canada, Taiwan, Iran, Japan, Korea and Australia (non-Indigenous) most likely originated from a single amphibian or reptilian lineage, which appears to have been previously geographically widespread. We identified a separate human lineage present in two Australian Indigenous isolates (independent geographical locations). This lineage is distinct and is present in Australian amphibians as well as a range of Australian marsupials.
authors.affiliation: Institute of Health and Biomedical Innovation, School of Life Sciences, Queensland University of Technology, Kelvin Grove, Queensland, Australia.
authors.forename: Candice M
authors.initials: CM
authors.lastname: Mitchell
authors.forename: Susan
authors.initials: S
authors.lastname: Hutton
authors.forename: Garry S A
authors.initials: GS
authors.lastname: Myers
authors.forename: Robert
authors.initials: R
authors.lastname: Brunham
authors.forename: Peter
authors.initials: P
authors.lastname: Timms
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura; D001315:Australia; D001426:Bacterial Proteins / Q000235:genetics; D002690:Chlamydia Infections / Q000382:microbiology*; D016993:Chlamydophila pneumoniae / Q000235:genetics*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D014644:Genetic Variation; D005838:Genotype; D006736:Horses; D006801:Humans; D008969:Molecular Sequence Data; D051189:Murinae; D048368:Phascolarctidae; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D048328:Potoroidae; D012104:Reptiles; D015047:Zoonoses / Q000382:microbiology*; D000095283:Australian Aboriginal and Torres Strait Islander Peoples
chemical_list: D001426:Bacterial Proteins