TABLE 2.

Distribution of virulence genes among clinical non-O1, non-O139 V. cholerae strains isolated from patients with acute diarrhea in 2003

No. of strainsPCR-based detectiona of virulence gene:
ctxAceptcpAtoxThlyArtxATTSSbVSP-IcVSP-IIdO1 wb
6e+++ (El)f++++++
1+++ (Env)g− (+)h+++
5+ (Env)g− (+)h+++
10+++
27++
1++++
1++
2+
7
  • a Symbols: +, PCR positive by generating the expected-size amplicon; −, no amplicon detected by the PCR assay.

  • b PCR-based detection of the TTSS gene cluster was based on the detection of vcsV2, vcsC2, vcsN2, and vspD.

  • c PCR-based detection of VSP-I was based on the detection of both VC0178 and VC0185.

  • d PCR-based detection of VSP-II was based on the detection of VC0516.

  • e All six strains were rough V. cholerae of O1 background.

  • f + (El), El Tor allele of tcpA.

  • g These strains gave a tcpA amplicon identical to the classical allele. However, nucleotide sequences were identical to tcpAEnv.

  • h These strains were PCR negative for toxT but positive by dot blot assay for toxT.