Polymerase chain reaction–amplified products from Rhipicephalus sanguineus ticks. Amplification of a 378-basepair (bp) product of the dsb protein gene and electrophoresis on a 1.5% agarose gel. B Lane 1, 100-bp molecular weight marker; lane 2, positive control E. canis plasmid DNA; lanes 3 and 4, negative controls; lanes 5–7 and 18, negative samples of DNA extracted from R. sanguineus ticks, lanes 8–17, positive samples of DNA extracted from individual R. sanguineus ticks.