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.
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