1887

Abstract

The operon, encoding cholera toxin (CT) in , is carried by the genome of a filamentous phage, CTXΦ. Usually, specific CTXΦ infect each of the two important biotypes, classical and El Tor, of epidemic strains belonging to serogroup O1, and are called CTXΦ and CTXΦ, respectively. However, an unusual hybrid El Tor strain carrying CTXΦ caused the cholera epidemic in Mozambique in 2004. To understand the evolution of that strain, we have further analysed some representative hybrid El Tor strains isolated in Kolkata, India, in 1992, and the results indicate that both the Mozambique and the Indian strains are infected with a unique CTXΦ having only four copies of the tandem heptamer repeat sequence 5′-TTTTGAT-3′ present in the promoter (P) region, like in CTXΦ. Usually, the P of the classical biotype contains seven to eight copies of such sequences. However, sequence analyses of the P regions of several classical strains indicated that the copy number of heptamer repeat sequences might vary from four to eight copies, which was previously unknown. Since the hybrid strains analysed in this study carry four copies of the heptamer sequences, it may thus serve as a marker to trace the strain in future. Interestingly, while the Mozambique strain is devoid of an El Tor-specific free RS1 element or pre-CTX prophage, the Indian hybrid strains carry such elements. The free RS1 has been mapped, cloned and sequenced. As in pre-CTX and CTX prophages, multiple copies of free RS1 elements were found to be integrated in tandem in the large chromosomal site. Since Indian hybrid El Tor strains carry either free RS1 or pre-CTX prophage in their large chromosomes, it is possible that the Mozambique hybrid El Tor strain has evolved from these progenitor strains by step-wise deletion of CTX genetic elements from their large chromosomes.

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2010-01-01
2020-01-21
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References

  1. Bhadra, R. K., Roychoudhury, S., Banerjee, R. K., Kar, S., Majumdar, R., Sengupta, S., Chatterjee, S., Khetawat, G. & Das, J. ( 1995; ). Cholera toxin (CTX) genetic element in Vibrio cholerae O139. Microbiology 141, 1977–1983.[CrossRef]
    [Google Scholar]
  2. Boyd, E. F., Heilpern, A. J. & Waldor, M. K. ( 2000; ). Molecular analyses of a putative CTXΦ precursor and evidence for independent acquisition of distinct CTXΦs by toxigenic Vibrio cholerae. J Bacteriol 182, 5530–5538.[CrossRef]
    [Google Scholar]
  3. Chatterjee, S., Patra, T., Ghosh, K., Raychoudhuri, A., Pazhani, G. P., Das, M., Sarkar, B., Bhadra, R. K., Mukhopadhyay, A. K. & other authors ( 2009; ). Vibrio cholerae O1 clinical strains isolated in 1992 in Kolkata with progenitor traits of the 2004 Mozambique variant. J Med Microbiol 58, 239–247.[CrossRef]
    [Google Scholar]
  4. Choudhury, S. R., Bhadra, R. K. & Das, J. ( 1994; ). Genomic size and restriction fragment length polymorphism analysis of Vibrio cholerae strains belonging to different serovars and biotypes. FEMS Microbiol Lett 115, 329–334.[CrossRef]
    [Google Scholar]
  5. Das, B., Halder, K., Pal, P. & Bhadra, R. K. ( 2007; ). Small chromosomal integration site of classical CTX prophage in Mozambique Vibrio cholerae O1 biotype El Tor strain. Arch Microbiol 188, 677–683.[CrossRef]
    [Google Scholar]
  6. Davis, B. M. & Waldor, M. K. ( 2000; ). CTXΦ contains a hybrid genome derived from tandemly integrated elements. Proc Natl Acad Sci U S A 97, 8572–8577.[CrossRef]
    [Google Scholar]
  7. Davis, B. M., Kimsey, H. H., Chang, W. & Waldor, M. K. ( 1999; ). The Vibrio cholerae O139 Calcutta bacteriophage CTXΦ is infectious and encodes a novel repressor. J Bacteriol 181, 6779–6787.
    [Google Scholar]
  8. Davis, B. M., Moyer, K. E., Boyd, E. F. & Waldor, M. K. ( 2000; ). CTX prophages in classical biotype Vibrio cholerae: functional phage genes but dysfunctional phage genomes. J Bacteriol 182, 6992–6998.[CrossRef]
    [Google Scholar]
  9. Davis, B. M., Kimsey, H. H., Kane, A. V. & Waldor, M. K. ( 2002; ). A satellite phage-encoded antirepressor induces repressor aggregation and cholera toxin gene transfer. EMBO J 21, 4240–4249.[CrossRef]
    [Google Scholar]
  10. Faruque, S. M., Asadulghani, Abdul Alim, A. R. M., Albert, M. J., Nasirul Islam, K. M. & Mekalanos, J. J. ( 1998; ). Induction of the lysogenic phage encoding cholera toxin in naturally occurring strains of toxigenic Vibrio cholerae O1 and O139. Infect Immun 66, 3752–3757.
    [Google Scholar]
  11. Faruque, S. M., Asadulghani, Kamruzzaman, M., Nandi, R. K., Ghosh, A. N., Nair, G. B., Mekalanos, J. J. & Sack, D. A. ( 2002; ). RS1 element of V. cholerae can propagate horizontally as a filamentous phage exploiting the morphogenesis genes of CTXΦ. Infect Immun 70, 163–170.[CrossRef]
    [Google Scholar]
  12. Faruque, S. M., Tam, V. C., Chowdhury, N., Diraphat, P., Dzieman, M., Heidelberg, J. F., Clemens, J. D., Mekalanos, J. J. & Nair, G. B. ( 2007; ). Genomic analysis of the Mozambique strain of Vibrio cholerae O1 reveals the origin of El Tor strains carrying classical CTX prophage. Proc Natl Acad Sci U S A 104, 5151–5156.[CrossRef]
    [Google Scholar]
  13. Heidelberg, J. F., Eisen, J. A., Nelson, W. C., Clayton, R. A., Gwinn, M. L., Dodson, R. J., Haft, D. H., Hickey, E. K., Peterson, J. D. & other authors ( 2000; ). DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae. Nature 406, 477–484.[CrossRef]
    [Google Scholar]
  14. Huber, K. E. & Waldor, M. K. ( 2002; ). Filamentous phage integration requires the host recombinases XerC and XerD. Nature 417, 656–659.[CrossRef]
    [Google Scholar]
  15. Hung, D. T. & Mekalanos, J. J. ( 2005; ). Bile acids induce cholera toxin expression in Vibrio cholerae in a ToxT-independent manner. Proc Natl Acad Sci U S A 102, 3028–3033.[CrossRef]
    [Google Scholar]
  16. Iwanaga, M., Yamamoto, K., Higa, N., Ichinose, Y., Nakasone, N. & Tanabe, M. ( 1986; ). Culture conditions for stimulating cholera toxin production by Vibrio cholerae O1 El Tor. Microbiol Immunol 30, 1075–1083.[CrossRef]
    [Google Scholar]
  17. Kaper, J. B., Morris, J. G., Jr & Levine, M. M. ( 1995; ). Cholera. Clin Microbiol Rev 8, 48–86.
    [Google Scholar]
  18. Lee, J. H., Han, K. H., Choi, S. Y., Lucas, M. E., Mondlane, C., Ansaruzzaman, M., Nair, G. B., Sack, D. A., von Seidlein, L. & other authors ( 2006; ). Multilocus sequence typing (MLST) analysis of Vibrio cholerae O1 El Tor isolates from Mozambique that harbour the classical CTX prophage. J Med Microbiol 55, 165–170.[CrossRef]
    [Google Scholar]
  19. Maiti, D., Das, B., Saha, A., Nandy, R. K., Nair, G. B. & Bhadra, R. K. ( 2006; ). Genetic organization of pre-CTX and CTX prophages in the genome of an environmental Vibrio cholerae non-O1, non-O139 strain. Microbiology 152, 3633–3641.[CrossRef]
    [Google Scholar]
  20. Mekalanos, J. J. ( 1983; ). Duplication and amplification of toxin genes in Vibrio cholerae. Cell 35, 253–263.[CrossRef]
    [Google Scholar]
  21. Mekalanos, J. J., Swartz, D. J., Pearson, G. D., Harford, N., Groyne, F. & de Wilde, M. ( 1983; ). Cholera toxin genes: nucleotide sequence, deletion analysis and vaccine development. Nature 306, 551–557.[CrossRef]
    [Google Scholar]
  22. Miller, V. L. & Mekalanos, J. J. ( 1984; ). Synthesis of cholera toxin is positively regulated at the transcription level by toxR. Proc Natl Acad Sci U S A 81, 3471–3475.[CrossRef]
    [Google Scholar]
  23. Miller, V. L. & Mekalanos, J. J. ( 1988; ). A novel suicide vector and its use in construction of insertion mutations: osmoregulation of outer membrane proteins and virulence determinants in Vibrio cholerae requires toxR. J Bacteriol 170, 2575–2583.
    [Google Scholar]
  24. Nair, G. B., Faruque, S. M., Bhuniyan, N. A., Kamaruzzaman, M., Siddque, A. K. & Sack, D. A. ( 2002; ). New variants of Vibrio cholerae O1 biotype El Tor with attributes of the classical biotype from hospitalized patients with acute diarrhoea in Bangladesh. J Clin Microbiol 40, 3296–3299.[CrossRef]
    [Google Scholar]
  25. Nandi, S., Maiti, D., Saha, A. & Bhadra, R. K. ( 2003; ). Genesis of variants of Vibrio cholerae O1 biotype El Tor: role of CTXΦ array and its position in the genome. Microbiology 149, 89–97.[CrossRef]
    [Google Scholar]
  26. Olsvik, O., Wahlberg, J., Petterson, B., Uhlén, M., Popovic, T., Wachsmuth, I. K. & Fields, P. I. ( 1993; ). Use of automated sequencing of polymerase chain reaction-generated amplicons to identify three types of cholera toxin subunit B in Vibrio cholerae O1 strains. J Clin Microbiol 31, 22–25.
    [Google Scholar]
  27. Pearson, G. D., Woods, A., Chiang, S. L. & Mekalanos, J. J. ( 1993; ). CTX genetic element encodes a site-specific recombination system and an intestinal colonization factor. Proc Natl Acad Sci U S A 90, 3750–3754.[CrossRef]
    [Google Scholar]
  28. Rubin, E. J., Lin, W., Mekalanos, J. J. & Waldor, M. K. ( 1998; ). Replication and integration of Vibrio cholerae cryptic plasmid linked to the CTX prophage. Mol Microbiol 28, 1247–1254.[CrossRef]
    [Google Scholar]
  29. Sack, D. A., Sack, R. B., Nair, G. B. & Siddique, A. K. ( 2004; ). Cholera. Lancet 363, 223–233.[CrossRef]
    [Google Scholar]
  30. Sambrook, J., Fritsch, E. F. & Maniatis, T. ( 1989; ). Molecular Cloning: a Laboratory Manual, 2nd edn. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory.
  31. Sharma, C., Nair, G. B., Mukhopadhyay, A. K., Bhattacharya, S. K., Ghosh, R. K. & Ghosh, A. ( 1997; ). Molecular characterization of Vibrio cholerae O1 biotype El Tor strains isolated between 1992 and 1995 in Calcutta, India: evidence for the emergence of a new clone of the El Tor biotype. J Infect Dis 175, 1134–1141.[CrossRef]
    [Google Scholar]
  32. Trucksis, M., Michalski, J., Deng, Y. K. & Kaper, J. B. ( 1998; ). The Vibrio cholerae genome contains two unique circular chromosomes. Proc Natl Acad Sci U S A 95, 14464–14469.[CrossRef]
    [Google Scholar]
  33. Udden, S. M. N., Zahid, M. S. H., Biswas, K., Ahmad, Q. S., Cravioto, A., Nair, G. B., Mekalanos, J. J. & Faruque, S. M. ( 2008; ). Acquisition of classical CTX prophage from Vibrio cholerae O141 by El Tor strains aided by lytic phages and chitin-induced competence. Proc Natl Acad Sci U S A 105, 11951–11956.[CrossRef]
    [Google Scholar]
  34. Val, M. E., Bouvier, M., Campos, J., Sherratt, D., Cornet, F., Mazel, D. & Barre, F. X. ( 2005; ). The single-stranded genome of phage CTX is the form used for integration into the genome of Vibrio cholerae. Mol Cell 19, 559–566.[CrossRef]
    [Google Scholar]
  35. Waldor, M. K. & Mekalanos, J. J. ( 1994; ). Emergence of a new cholera pandemic: molecular analysis of virulence determinants in Vibrio cholerae O139 and development of a live vaccine prototype. J Infect Dis 170, 278–283.[CrossRef]
    [Google Scholar]
  36. Waldor, M. K. & Mekalanos, J. J. ( 1996; ). Lysogenic conversion by a filamentous phage encoding cholera toxin. Science 272, 1910–1914.[CrossRef]
    [Google Scholar]
  37. Waldor, M. K., Rubin, E. J., Pearson, G. D., Kimsey, H. & Mekalanos, J. J. ( 1997; ). Regulation, replication, and integration functions of the Vibrio cholerae CTXΦ are encoded by region RS2. Mol Microbiol 24, 917–926.[CrossRef]
    [Google Scholar]
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PCR analysis of the large chromosomal CTX element integration sites of hybrid El Tor strains VC44 and VC106 [PDF](274 KB)

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