Amplification of the AM415 INDEL in A. marginale strains and field isolates. Panel A shows amplification of the AM415 INDEL in the Dawn and Gypsy Plains strains with two different primer sets. Lanes 1 and 5 contain DNA from the Dawn strain, lanes 2 and 6 contain DNA from the Gypsy Plains strain, lanes 3 and 7 contain DNA from the unrelated tick-borne pathogen Babesia bovis and lanes 4 and 8 contain a water control (no template). Lanes marked M is the 1kb Plus DNA ladder (Life TechnologiesTM) with bands of 1,000 and 2,000 bp indicated on the left. Lanes 1–4 show results using primer set AM415 designed to sit inside of the INDEL and show the absence of amplicon in the Dawn strain. The expected size of the product was 1,027 bp in Gypsy Plains. Lanes 5–8 show results using primer set AM415L which is designed to show a size difference between the Gypsy Plains and Dawn strains by flanking the INDEL. The expected size of the products was 1,684 bp for Gypsy Plains and 331 bp for Dawn. Panel B shows usage of primer set AM415L with several virulent field isolates. Lane 1 shows the Dawn strain, lane 2 field isolate P11-72270, lane 3 shows the Gypsy Plains strain and lanes 4 through 6 show isolates P11-702600009, P11-702600001 and P11-702600005 respectively.