Genetic characterization of hydatid cysts of different intermediate hosts

Cystic echinococcosis is an important cosmopolitan parasitic zoonosis that causes public health and economic problems in Egypt. The present study was undertaken to identify genotypes of hydatid cyst (HC) DNA isolated from different animal isolates and to identify the genotype of secondary hydatid cysts (HCs) developed in rabbits experimentally infected with camel HC for detection of any genetic mutation. In the present study, we extracted DNA from the germinal layers of 8 HCs collected from 3 camels, 1 cattle, 1 sheep and 3 donkeys in addition to 3 secondary HCs collected from rabbits experimentally infected with camel HC. PCR amplification of the ITS1 gene of all examined samples showed an amplified DNA band at 1115 bp. The partial nucleotide sequences of the ITS1 gene of all isolates were aligned and compared with the reference sequences of the genotypes G1–G8 in GenBank. The camel and rabbit samples were identified as Echinococcus canadensis genotype 6 (G6), while the cattle and sheep samples belonged to E. granulosus sensu stricto (G1). The donkey isolates belonged to E. equines (G4). Alignment of the ITS1 partial nucleotide sequences of the camel HCs and rabbit secondary HCs isolates with the G6 partial nucleotide sequence in GenBank was performed. Both camel HCs and rabbit secondary HCs isolates exhibited the same sequence identity matrix, which indicated the absence of mutation in the rabbit secondary HCs. It can be concluded that camel and rabbit samples were identified as E. canadensis (G6), the cattle and sheep samples belonged to E. granulosus sensu stricto (G1) and donkey isolates belonged to E. equines (G4). No mutation occurred during HCs transmission from camel to rabbit.