Population genetics of Vibrio vulnificus: identification of two divisions and a distinct eel-pathogenic clone.
Genetic relationships among 62 Vibrio vulnificus strains of different geographical and host origins were analyzed by multilocus enzyme electrophoresis (MLEE), random amplification of polymorphic DNA (RAPD), and sequence analyses of the recA and glnA genes. Out of 15 genetic loci analyzed by MLEE, 11 were polymorphic. Cluster analysis identified 43 distinct electrophoretic types (ETs) separating the V. vulnificus population into two divisions (divisions I and II). One ET (ET 35) included all indole-negative isolates from diseased eels worldwide (biotype 2). A second ET (ET 2) marked all of the strains from Israel isolated from patients who handled St. Peter's fish (biotype 3). RAPD analysis of the 62 V. vulnificus isolates identified 26 different profiles separated into two divisions as well. In general, this subdivision was comparable (but not identical) to that observed by MLEE. Phylogenetic analysis of 543 bp of the recA gene and of 402 bp of the glnA gene also separated the V. vulnificus population into two major divisions in a manner similar to that by MLEE and RAPD. Sequence data again indicated the overall subdivision of the V. vulnificus population into different biotypes. In particular, indole-negative eel-pathogenic isolates (biotype 2) on one hand and the Israeli isolates (biotype 3) on the other tended to cluster together in both gene trees. None of the methods showed an association between distinct clones and human clinical manifestations. Furthermore, except for the Israeli strains, only minor clusters comprising geographically related isolates were observed. In conclusion, all three approaches (MLEE, RAPD, and DNA sequencing) generated comparable but not always equivalent results. The significance of the two divisions (divisions I and II) still remains to be clarified, and a reevaluation of the definition of the biotypes is also needed.
Gutacker
Michaela
M
Istituto Cantonale di Microbiologia, 6501 Bellinzona, Switzerland.
Conza
Nadine
N
Benagli
Cinzia
C
Pedroli
Ambra
A
Bernasconi
Marco Valerio
MV
Permin
Lise
L
Aznar
Rosa
R
Piffaretti
Jean-Claude
JC
D000818:Animals; D015373:Bacterial Typing Techniques; D004524:Eels / Q000382:microbiology*; D004586:Electrophoresis / Q000379:methods; D005393:Fish Diseases / Q000382:microbiology; D014644:Genetic Variation; D005828:Genetics, Population; D005974:Glutamate-Ammonia Ligase / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D019105:Random Amplified Polymorphic DNA Technique; D011938:Rec A Recombinases / Q000235:genetics; D017422:Sequence Analysis, DNA; D014735:Vibrio Infections / Q000382:microbiology* / Q000662:veterinary; D041261:Vibrio vulnificus / Q000145:classification* / Q000235:genetics* / Q000472:pathogenicity
D011938:Rec A Recombinases; C081173:glutamine synthetase I; D005974:Glutamate-Ammonia Ligase