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Evidence that Human Chlamydia pneumoniae Was Zoonotically Acquired∇

G. S. A. Myers,1* S. A. Mathews,2 M. Eppinger,1 C. Mitchell,2 K. K. O’Brien,1 O. R. White,1 F. Benahmed,3 R. C. Brunham,4 T. D. Read,5 J. Ravel,1 P. M. Bavoil,6 and P. Timms2

1 Institute for Genome Sciences, University of Maryland, Baltimore, Maryland 21201

2 Institute of Health & Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059, Australia2;

3 J. Craig Venter Institute, 9712 Medical Center Drive, Rockville, Maryland 20850

4 University of British Columbia Centre for Disease Control, 655 West 12th Avenue, Vancouver, British Columbia V5Z 4R4, Canada

5 Division of Infectious Diseases & Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Atlanta, Georgia 30322

6 Department of Microbial Pathogenesis, University of Maryland Baltimore, 650 West Baltimore Street, Baltimore, Maryland 21201


Zoonotic infections are a growing threat to global health. Chlamydia pneumoniae is a major human pathogen that is widespread in human populations, causing acute respiratory disease, and has been associated with chronic disease. C. pneumoniae was first identified solely in human populations; however, its host range now includes other mammals, marsupials, amphibians, and reptiles. Australian koalas (Phascolarctos cinereus) are widely infected with two species ofChlamydia, C. pecorum and C. pneumoniae. Transmission of C. pneumoniae between animals and humans has not been reported; however, two other chlamydial species, C. psittaci and C. abortus, are known zoonotic pathogens. We have sequenced the 1,241,024-bp chromosome and a 7.5-kb cryptic chlamydial plasmid of the koala strain of C. pneumoniae (LPCoLN) using the whole genome shotgun method. Comparative genomic analysis, including pseudogene and single nucleotide polymorphism (SNP) distribution, and phylogenetic analysis of conserved genes and SNPs against the human isolates of C. pneumoniae show that the LPCoLN isolate is basal to human isolates. Thus, we propose based on compelling genomic and phylogenetic evidence that humans were originally infected zoonotically by an animal isolate(s) of C. pneumoniae which adapted to humans primarily through the processes of gene decay and plasmid loss, to the point where the animal reservoir is no longer required for transmission.

  • All
  • 2013
  • Biogeography
  • Biology
  • Chlamydia
  • Diet
  • Disease
  • Ecology
  • Ellis
  • Eucalyptus
  • Genetics
  • Habitat
  • Infection
  • Interventions
  • Koala
  • Lunney
  • Threats
  • Timms
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