Results of AP-PCR assay for O3:K6 strains isolated in Bangladesh. The results obtained with primer 1 are shown in A1 and B1, and those obtained with primer 2 are presented in A2 and B2. (A1 and A2) Lanes: 1 and 13, molecular size markers (phage λ DNA digested with HindIII); 2 and 14, molecular size markers (phage φX174 DNA digested with HaeIII); 3 and 12, strain VP47 (a control strain isolated in Calcutta in 1996 [16]); 4 through 9, Bangladeshi strains isolated in 1980; 10 and 11, Bangladeshi strains isolated in 1981. (B1 and B2) Lanes: 1 and 15, molecular size markers (phage λ DNA digested with HindIII); 2 and 14, molecular size markers (phage φX174 DNA digested with HaeIII); 3 and 13, VP47; 4 through 10, Bangladeshi strains isolated in 1996; 11 and 12, Bangladeshi strains isolated in 1997.