FIG. 2.

One percent agarose gels with ethidium bromide showing examples of PCR-based vacA midregion typing by new strategy 1 (A) and new strategy 2 (B). Details about the PCR primers and expected product sizes are given in the text and in Fig. 1. The PCR products shown were amplified from the following nine strains (in the lanes from left to right), respectively: J238 (from the United States, m1 control), J226 (from the United States, m2 control), Ch2 (from China, m1/m2 hybrid), Ch3 (from China, m1), Ch4 (from China, m2), Ch5 (from China, m1), Ch7 (from China, m1), Ch8 (from China, m1), and 92-24 (from the United States m1 control).