Infectivity, transmission and 16S rRNA sequencing of a rickettsia, Coxiella cheraxi sp. nov., from the freshwater crayfish Cherax quadricarinatus.
A rickettsia-like organism isolated from infected, farm-reared Cherax quadricarinatus was cultured in the yolk sac of developing chicken eggs, but could not be cultured in 3 continuous cell lines, bluegill fry (BF-2), fathead minnow (FHM), and Spodoptera frugiperda (Sf-9). The organism was confirmed by fulfilling Koch's postulates as the aetiological agent of mortalities amongst C. quadricarinatus. When C. quadricarinatus was inoculated with the organism, mortality was 100% at 28 degrees C and 80% at an ambient temperature of 24 degrees C. Horizontal transmission with food and via the waterborne route was demonstrated, but mortalities were lower at 30 and 10% respectively over a 4 wk period. The 16S rRNA sequence of 1325 base pairs of the Gram-negative, obligate intracellular organism was 95.6% homologous to Coxiella burnetii. Of 18 species compared to this rickettsia, the next most closely related bacterium was Legionella pneumophila at 86.7%. The suggested classification of this organism is Order Rickettsiales, family Rickettsiaceae, tribe Rickettsieae, within the genus Coxiella. We suggest it should be named Coxiella cheraxi sp. nov.
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Department of Microbiology and Immunology, James Cook University, Townsville, Australia.
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D000818:Animals; D017756:Aquaculture; D003400:Astacoidea / Q000382:microbiology*; D001483:Base Sequence; D002642:Chick Embryo; D016384:Consensus Sequence; D003381:Coxiella / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D004269:DNA, Bacterial / Q000737:chemistry; D008969:Molecular Sequence Data; D010802:Phylogeny; D011793:Queensland; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D013047:Specific Pathogen-Free Organisms
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S