Antigenic and genotypic characterization of Echinococcus granulosus larval isolates from Egypt

Abstract

Background: Cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus, is a global zoonotic infection of economic importance constituting a threat to public health in many countries. E. granulosus exists as a complex of different strains that have an impact on the epidemiology and control of CE, the most important of which are G1 and G6 strains. In Egypt, some studies confirm the predominance of G1 strain while others demonstrated the involvement of camel G6 strain in causing human infection. Objective: To study the diagnostic potential of purified antigenic yields of hydatid cyst fluid (HCF) from Egyptian CE patients and DNA corresponding to different recorded genotypes, in addition to the characterization of E. granulosus genotype in human and animal isolates in Egypt. Subjects and Methods: Crude HCF antigens from 30 patients were extracted and fractionated by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) and probed by enzyme immunoelectrotransfer blot (EITB) against sera from CE patients and 50 controls. HCF from human and animal isolates was obtained and prepared for DNA extraction and the amplification of the predominant genotype bands at 254 bp. Results: PCR applied to HCF protoscolices of human and camels showed a typical 254 bp band of 12S fragment of mitochondrial gene belonging to G6 genotype (camel strain). SDS-PAGE fractionation of crude HCF antigen gave a protein profile composed of 11 bands. Immunoblotting assay showed that anti-E. granulosus IgG of patients' sera recognized 9 antigenic bands, varying in molecular weight from 12-110 kDa. The 48 and 12 kDa bands detected in all patients' sera disappeared after treatment. Conclusion: This study confirmed the predominance of G6 genotype (camel strain) of cystic echinococcosis in Egypt. PCR using the amplification primers of G6 genotype is a promising tool in the diagnosis of CE using either patients' HCF or sera. The use of EITB in the diagnosis and post-treatment follow up of G6 genotype CE patients proved of high sensitivity and specificity. The recognition of 48 and 12 kDa antigenic proteins in 100% of CE cases' sera and their disappearance after treatment marks their usefulness in diagnosis and follow up of CE cases.

Immunological detection of human and camel cystic echinococcosis using different antigens of hydatid cyst fluid, protoscoleces, and germinal layers

“…CE diagnosis remains difficult, although effective serological diagnoses provide opportunities for early treatment, post-treatment follow-up, and more effective chemotherapy [9]. Enzyme-linked immunosorbent assay (ELISA) is beneficial for CE diagnosis in humans and domestic animals.…”

“…granulosus, formerly regarded as a single species with high genotypic and phenotypic diversity, is now recognized as a multiple cryptic species that considerably in morphology, development, and host specificity (including human infectivity/pathogenicity) among others. [9]. Based on phenotypic characteristics and gene sequences, E. granulosus (sensu lato) is now subdivided into E. granulosus (sensu stricto) (including G1-3), Echinococcus felidis (the "lion strain"), Echinococcus equinus (the "horse strain," genotype G4), Echinococcus ortleppi (the "cattle strain," and genotype G5), and Echinococcus canadensis.…”