Comparison of Isoenzyme pattern of Echinococcus granulosus sensu stricto (G1-G3) and E. canadensis (G6/G7) protoscoleces according to their Host Variation in Iran

Different genotypes of Echinococcus granulosus sensu lato can infect humans and animals. The simultaneous occurrence of the isoenzymes and molecular characterization of this important zoonotic parasite have not been yet investigated in Iran. This study aims to evaluate the isoenzyme pattern of the larval stage of Echinococcus spp. genotypes according to their host types in the country.

Thirty-two (8 humans and 24 animals) hydatid cyst isolates were collected from May 2018 to December 2020. DNAs were extracted using a DNA extraction kit, and their genotypes were determined by molecular methods to identify the presence of different species/genotypes of E. granulosus sensu lato. Enzymes were extracted from the cyst and subjected to polyacrylamide gel electrophoresis. The activities of glucose 6-phosphate dehydrogenase (G6PD), malate dehydrogenase (MDH), malic enzyme (ME), nucleoside hydrolyse 1 (NH1), and isocitrate dehydrogenase (ICD) were assessed in the cyst samples. The results were compared with the genotyping findings.

DNA sequence analysis of the samples showed that the specimens contained 75% E. granulosus sensu stricto (G1) and 25% E. canadensis (G6) genotypes. The isoenzyme pattern of ICD for both genotypes produced a six-band pattern with different relative factors.  Moreover, the G6PD produced two bands with different relative migration in both genotypes. The MDH and NH1 systems exhibited a two-band pattern, while only one band was observed in the ME enzyme of the E. granulosus sensu stricto genotype. Furthermore, in E. canadensis, the MDH and NH1 enzymes showed one band, and the ME enzyme represented a two-band pattern.

Our findings reveal that E. granulosus sensu stricto and E. canadensis genotypes have entirely different isoenzyme patterns for NH1, G6PD, MDH, and ME. Therefore, these enzyme systems may be used for the differentiation of these two genotypes of Echinococcus granulosus.