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. 2010 Jun 14;78(9):3660–3668. doi: 10.1128/IAI.00386-10

FIG. 7.

FIG. 7.

CEL I digestion of the D-EC, D-LC, and reference serovar D strains. CT135 PCR amplicons of D-EC, D-LC, a mixture of each strain, and the parental reference serovar D strain were digested with the mismatch-specific nuclease CEL I. Before digestion, the PCR products were heat denatured and reannealed to allow possible heteroduplexes to form. D-EC and D-LC have only the uncleaved 1,217-bp full-length CT135 PCR product. The 1:1 mixture of D-EC and D-LC exhibits five digestion products: 628 bp and 589 bp as a result of cleaving the D-EC mutation, 1,001 bp and 216 bp as a result of cleaving the D-LC mutation, and 412 bp as a result of cleaving both the D-EC and D-LC mutations (the complete digestion of a heteroduplex). In the parental serovar D strain, the 1,001-bp band is significantly weaker than that for the D-EC and D-LC mixture, and the 412-bp and 216-bp bands are not detectable, all of which are likely related to a low abundance of D-LC in the parental serovar D strain. The bands associated with D-EC are easily recognizable, as are two other bands (685 bp and 532 bp, indicated by asterisks), suggesting the presence of other genotypes in the parental serovar D strain.