High resolution melting technique for molecular epidemiological studies of cystic echinococcosis: differentiating G1, G3, and G6 genotypes of Echinococcus granulosus sensu lato.

Reliable and rapid genotyping of large number of Echinococcus granulosus sensu lato isolates is crucial for understanding the epidemiology and transmission of cystic echinococcosis. We have developed a method for distinguishing and discriminating common genotypes of E. granulosus s.l. (G1, G3, and G6) in Iran. This method is based on polymerase chain reaction coupled with high resolution melting curve (HRM), ramping from 70 to 86 °C with fluorescence data acquisition set at 0.1 °C increments and continuous fluorescence monitoring. Consistency of this technique was assessed by inter- and intra-assays. Assessment of intra- and inter-assay variability showed low and acceptable coefficient of variations ranging from 0.09 to 0.17 %. Two hundred and eighty E. granulosus s.l. isolates from sheep, cattle, and camel were used to evaluate the applicability and accuracy of the method. The isolates were categorized as G1 (93, 94, and 25%), G3 (7, 4, and 4%), and G6 (0, 2, and 71%) for sheep, cattle, and camel, respectively. HRM results were completely compatible with those obtained from sequencing and rostellar hook measurement. This method proved to be a valuable screening tool for large-scale molecular epidemiological studies.