Fig 2.

Salmonella recF-specific primers produce LAMP target amplicons that contain an E-DNA target region. (A) A LAMP primer set was designed that amplified a region of the recF gene in Salmonella that contains a 22-base, single-stranded E-DNA target region (yellow), shown here for S. Typhimurium. *, bases that differ between the serovars. (B) A polyacrylamide gel loaded with triplicate LAMP reactions of S. Typhimurium (lanes 1 to 3) and S. Choleraesuis (lanes 4 to 6). The LAMP products derived from different serovars differ in sequence but are indistinguishable in terms of product lengths. (C) The lowest-molecular-size LAMP products that we detect are ∼150-base, barbell-like structures with a single-stranded loop region (in yellow) containing a 22-base, single-stranded sequence complementary to the E-DNA probes (Table 2).