Emergence and genetic diversity of El Tor Vibrio cholerae O1 that possess classical biotype ctxB among travel-associated cases of cholera in Japan.
Vibrio cholerae O1 are classified into two biotypes, classical and El Tor, each encoding a biotype-specific cholera toxin. However, El Tor strains have recently emerged with a classical cholera-toxin genotype (El Tor variant). We characterized El Tor strains of V. cholerae O1 from travel-associated cases of cholera in Japan isolated from 1991 to 2006 by cholera toxin B subunit gene (ctxB) typing and by molecular epidemiological methods. ctxB in the biotype El Tor shifted from the El Tor-specific type to the classical-specific type around 1993, and this type fully dominated the later half of the 1990s. Based on the results of PFGE and multilocus variable-number tandem repeat analysis, strains of the classical biotype remained diverse from those of El Tor biotype. The El Tor biotype strains formed multiple minor clusters and intermingled with each other irrespective of their origins and toxin types. El Tor variant strains are widespread in Asian countries and show significant genetic diversity, indicating that their spread is a result of multiclonal expansion rather than spread from a single clone.
Morita
Masatomo
M
Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Ohnishi
Makoto
M
Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Arakawa
Eiji
E
Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Yamamoto
Shouji
S
Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Nair
G Balakrish
GB
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Matsushita
Shigeru
S
Tokyo Metropolitan Institute of Public Health, Tokyo, Japan.
Yokoyama
Keiko
K
Tokyo Metropolitan Institute of Public Health, Tokyo, Japan.
Kai
Akemi
A
Tokyo Metropolitan Institute of Public Health, Tokyo, Japan.
Seto
Kazuko
K
Osaka Prefectural Institute of Public Health, Osaka, Japan.
Watanabe
Haruo
H
Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Izumiya
Hidemasa
H
Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
D015373:Bacterial Typing Techniques; D002771:Cholera / Q000382:microbiology*; D002772:Cholera Toxin / Q000235:genetics*; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D016521:Electrophoresis, Gel, Pulsed-Field; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007564:Japan; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D014195:Travel; D041241:Vibrio cholerae O1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*
D002772:Cholera Toxin