1887

Microbiology Society logo

Volume 149, Issue 1

Genesis of variants of O1 biotype El Tor: role of the CTXϕ array and its position in the genome Free

Abstract

The gene encoding cholera toxin, the principal virulence factor of , is encoded by a filamentous, lysogenic bacteriophage known as CTXϕ. The genome of , the host for CTXϕ, consists of two chromosomes, one large and one small. Here, it is shown that localization and array of CTX prophage DNA in either the large or small chromosome of is likely to be one of the reasons for the emergence of O1 biotype El Tor variants isolated just before and after the O139 cholera outbreak in 1992. Analyses of the organization of the CTX region of the genome of pre-O139 El Tor strains revealed that these strains carry two distinct CTX prophages integrated in the small chromosome in tandem: CTX, the prophage having a conserved I site in its repeat sequence segment which seems to be specific for the El Tor strains so far examined, followed by CTX-like genome, the prophage found in recent O139 clinical isolates from Calcutta. In sharp contrast, in post-O139 El Tor strains only one copy of the CTX prophage was found to be integrated in the large chromosome. To the authors' knowledge, the presence of CTX prophage in the small chromosome of O1 El Tor strains has not been reported previously. It is also shown that the difference in the CTX copy number and the position of the bacteriophage on the genomes of pre- and post-O139 El Tor strains have an effect on cholera toxin production. While a pre-O139 strain produced maximum cholera toxin in yeast extract/peptone medium at 30 °C, a post-O139 El Tor strain showed maximal yield at 37 °C, indicating differential regulation of cholera toxin between the strains. It appears from this study that the variation in the integration site of the CTX prophage, its copy number and the presence of diverse phage genomes in O1 biotype El Tor may be strategically important for generating variants with subtle phenotypic modulations of virulence factor production in this longest-ruling seventh pandemic strain.

  • Received:
  • Accepted:
  • Revised:
  • Published Online:
Keyword(s): CT, cholera toxin and RS, repeat sequence
SGM
Loading

Article metrics loading...

/content/journal/micro/10.1099/mic.0.25599-0
2003-01-01
2024-04-18
Loading full text...

Full text loading...

/deliver/fulltext/micro/149/1/mic149_10.html?itemId=/content/journal/micro/10.1099/mic.0.25599-0&mimeType=html&fmt=ahah

References

  1. Albert M. J, Siddique A. K, Islam M. S, Faruque A. S, Ansaruzzaman M, Faruque S. M., Sack R. B. 1993; Large outbreak of clinical cholera due to Vibrio cholerae non-O1 in Bangladesh. Lancet 341:704
     [Google Scholar]
  2. Baudry B, Fasano A, Ketley J., Kaper J. B. 1992; Cloning of a gene ( zot ) encoding a new toxin produced by Vibrio cholerae . Infect Immun 60:428–434
     [Google Scholar]
  3. Bhadra R. K, Roychoudhury S., Das J. 1994; Vibrio cholerae O139 El Tor biotype. Lancet 343:728
     [Google Scholar]
  4. 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
     [Google Scholar]
  5. Bik E. M, Bunschoten A. E, Gouw R. D., Mooi F. 1995; Genesis of the novel epidemic Vibrio cholerae O139 strain: evidence of horizontal transfer of genes involved in polysaccharide synthesis. EMBO J 14:209–216
     [Google Scholar]
  6. Chakraborty S, Mukhopadhyay A. K, Bhadra R. K. 8 other authors 2000; Virulence genes in environmental strains of Vibrio cholerae . Appl Environ Microbiol 66:4022–4028
     [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
     [Google Scholar]
  9. Faruque S. M, Albert M. J., Mekalanos J. J. 1998; Epidemiology, genetics and ecology of toxigenic Vibrio cholerae . Microbiol Mol Biol Rev 62:1301–1314
     [Google Scholar]
  10. Heidelberg J. F, Eisen J. A, Nelson W. C. 29 other authors 2000; DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae . Nature 406:477–484
     [Google Scholar]
  11. Kaper J. B, Morris J. G. Jr, Levine M. M. 1995; Cholera. Clin Microbiol Rev 8:48–86
     [Google Scholar]
  12. Karaolis D. K. R, Johnson J. A, Bailey C. C, Boedecker E. C, Kaper J. B., Reeves P. R. 1998; A Vibrio cholerae pathogenicity island associated with epidemic and pandemic strains. Proc Natl Acad Sci U S A 95:3134–3139
     [Google Scholar]
  13. Karaolis D. K. R, Somara S, Maneval D. R. Jr, Johnson J. A., Kaper J. B. 1999; A bacteriophage encoding pathogenicity island, a type-IV pilus and a phage receptor in cholera bacteria. Nature 399:375–379
     [Google Scholar]
  14. Khetawat G, Bhadra R. K, Nandi S., Das J. 1999; Resurgent Vibrio cholerae O139: rearrangement of cholera toxin genetic elements and amplification of rrn operon. Infect Immun 67:148–154
     [Google Scholar]
  15. Kimsey H. H., Waldor M. K. 1998; CTXϕ immunity: application in the development of cholera vaccines. Proc Natl Acad Sci U S A 95:7035–7039
     [Google Scholar]
  16. Kimsey H. H, Nair G. B, Ghosh A., Waldor M. K. 1998; Diverse CTXϕs and evolution of new pathogenic Vibrio cholerae . Lancet 352:457–458
     [Google Scholar]
  17. Levine M. M. 1991; South America: the nature of cholera. Lancet 341:45–46
     [Google Scholar]
  18. Lin W, Fullner K. J, Clayton R, Saxton J. A, Rogers M. B, Calia K. E, Calderwood S. B, Fraser C., Mekalanos J. J. 1999; Identification of a Vibrio cholerae RTX toxin gene cluster that is tightly linked to the cholera toxin prophage. Proc Natl Acad Sci U S A 96:1071–1076
     [Google Scholar]
  19. Mekalanos J. J. 1983; Duplication and amplification of toxin genes in Vibrio cholerae . Cell 35:253–263
     [Google Scholar]
  20. Mukhopadhyay A. K, Garg S, Nair G. B. 7 other authors 1995; Biotype traits and antibiotic susceptibility of Vibrio cholerae serogroup O1 before, during and after the emergence of the O139 serogroup. Epidemiol Infect 115:427–434
     [Google Scholar]
  21. Mukhopadhyay A. K, Garg S, Mitra R. 8 other authors 1996a; Temporal shifts in traits of Vibrio cholerae strains isolated from hospitalized patients in Calcutta: a 3-year (1993 to 1995) analysis. J Clin Microbiol 34:2537–2543
     [Google Scholar]
  22. Mukhopadhyay A. K, Garg S, Saha P. K, Takeda Y, Bhattacharya S. K., Nair G. B. 1996b; Comparative analysis of factors promoting optimal production of cholera toxin by Vibrio cholerae O1 (classical and El Tor biotypes) and O139. Indian J Med Res 104:129–133
     [Google Scholar]
  23. Nair G. B. 1996; Molecular insights into the evolution and epidemiology of Vibrio cholerae . Indian J Med Res 104:5–13
     [Google Scholar]
  24. Nandi S, Khetawat G, Sengupta S, Majumder R, Kar S, Bhadra R. K, Roychoudhury S., Das J. 1997; Rearrangements in the genomes of Vibrio cholerae strains belonging to different serovars and biovars. Int J Syst Bacteriol 47:858–862
     [Google Scholar]
  25. Pearson G. D. N, 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
     [Google Scholar]
  26. Ramamurthy T, Garg S, Sharma R. 8 other authors 1993; Emergence of novel strain of Vibrio cholerae with epidemic potential in Southern and Eastern India. Lancet 341:703–704
     [Google Scholar]
  27. 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
     [Google Scholar]
  28. Sambrook J, Fritsch E. F., Maniatis T. 1989 Molecular Cloning: a Laboratory Manual, 2nd edn. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory;
     [Google Scholar]
  29. 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
     [Google Scholar]
  30. Trucksis M, Galen J. E, Michalsky J, Fasano A., Kaper J. B. 1993; Accessory cholera enterotoxin (Ace), the third toxin of a Vibrio cholerae virulence cassette. Proc Natl Acad Sci U S A 90:5267–5271
     [Google Scholar]
  31. Trucksis M, Michalsky 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
     [Google Scholar]
  32. Waldor M. K., Mekalanos J. J. 1994; Emergence of 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
     [Google Scholar]
  33. Waldor M. K., Mekalanos J. J. 1996; Lysogenic conversion by a filamentous phage encoding cholera toxin. Science 272:1910–1914
     [Google Scholar]
  34. Waldor M. K, Rubin E. J, Pearson G. D. N, Kimsey H., Mekalanos J. J. 1997; Regulation, replication, and integration functions of the Vibrio cholerae (CTX) are encoded by region RS2. Mol Microbiol 24:917–926
     [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/mic.0.25599-0
Loading
Genesis of variants of Vibrio cholerae O1 biotype El Tor: role of the CTXϕ array and its position in the genome
Microbiology 149, 89 (2003); https://doi.org/10.1099/mic.0.25599-0
/content/journal/micro/10.1099/mic.0.25599-0
/content/journal/micro/10.1099/mic.0.25599-0
Loading

Data & Media loading...

Most cited Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error