FIG. 1.

Subtyping of Stx2 subtypes by RFLP-PCR. (A) Schematic representation of the restriction patterns obtained with the RFLP-PCR method developed by Tyler et al. (25). (B) Predicted sizes of the amplified products obtained with the VT2c and VT2d oligonucleotide primers and restricted with HaeIII, RsaI, and NciI endonuclease. The method developed to screen the Stx2vh-a subtype should also detect Stx2c and Stx2-OX3b because the nucleotide sequences of primers and sites of the restriction endonucleases used in the RFLP-PCR method were conserved among Stx2vh-a, Stx2c, and Stx2-OX3b genes. Similarly, the protocol used to discriminate Stx2-EDL933 should also detect Stx2-O48. The nucleotide sequence of Stx2-O113 is not available in the databases.