PCR-RFLP profiles of the PLB1 gene obtained from serotype AD clones of strain WM329 = 90-7031 (see hybrid RFLP profile in lane 3, Fig. 1A), with AvaI. Strain H99, serotype A, RFLP profile A1, molecular type VNI; strain WM629, serotype D, RFLP profile A4, molecular type VNIV; clones 1 to 6, clones of strain WM329 = 90-7031 (clones 1 and 3, RFLP profile A1; clones 2, 4, 5, and 6, RFLP profile A4).