MLVA genotyping data and cluster analysis. Cluster analysis was performed using the categorical and unweighted-pair group method using arithmetic averages (UPGMA) options. From left to right, the columns designate the MLVA types, plague foci, biovar, and number of isolates with identical MLVA type and plague focus, repeat number of 14 loci (M76, M73, M72, M66, M61, ms01, M59, M58, M55, M54, M52, M51, M49, and M37). EV (MT70) is strain EV76, which is the vaccine strain. The details of group A, B, C and D were in the text.