Antigenic differences between the EG95‐related proteins from Echinococcus granulosus G1 and G6 genotypes: implications for vaccination

Abstract

Cystic echinococcosis caused by Echinococcus granulosus remains an important and neglected issue in public health. The study of the likely efficacy of the currently available EG95 vaccine against other genotypes of the parasite is important to improve the vaccine as a potential tool to be used in control programmes. The recombinant vaccine EG95-1G1 was developed based on the G1 genotype of E. granulosus. Characterization of the eg95 gene family in the G6 genotype by genomic DNA cloning previously produced the first unequivocal information about the composition of the gene family in a different genotype. The information was used in this study to predict and express two EG95-related proteins from the G6 genotype as recombinants, for assessment of their capacity to bind antibodies raised in sheep vaccinated with the EG95-1G1 vaccine. The proteins (EG95-1G6 and EG95-5G6) from the G6 genotype of E. granulosus were unable to bind all the antibodies raised by sheep vaccinated with EG95-1G1. Differences in the amino acid sequence of EG95-related proteins from G6 and likely the differences in the encoded FnIII domain may be responsible for changes in the conformation of these epitopes.

Cystic echinococcosis in South America: systematic review of species and genotypes of Echinococcus granulosus sensu lato in humans and natural domestic hosts

“…The G6 genotype displays features that are important for cystic echinococcosis diagnosis and control such as sequence variability in the diagnostic antigen B and the vaccine EG95 antigen . Also, differences in anti‐EG95 antibody response to infection between the G1 and G6 genotypes have been described . Echinococcus equinus (G4 genotype) has not been identified in South America yet, since the cystic echinococcosis cases found in horses lack genotype determination .…”

“…Also, E. canadensis (G6 genotype) plays a significant role in South American human cystic echinococcosis. Taking into account the molecular epidemiological situation, it is relevant to evaluate the pathogenicity, diagnosis performance and response to chemotherapy of the G6 genotype since antigenic differences between the EG95‐related proteins from the G1 and G6 genotypes were observed . Additionally, for an accurate determination of the public health relevance of E. canadensis (G7 genotype) in South America, a molecular epidemiological survey should be carried out in those regions where swine breeding is concentrated.…”

“…This term was due to the observation of radical differences in the in vitro development of protoscoleces isolated from sheep and horse cysts . Since then, more strains were identified and several works have shown that the strains differ in many features such as protein profile , carbohydrate and lipid repertoires , hooks morphology , metabolic requirements (reviewed in ), fertile cyst development in natural infections (reviewed in 11), cyst development in experimental infections , intermediate host specificity, pre‐patent period , antigenicity and infectivity and pathogenicity in humans .…”

Echinococcus P29 Antigen: Molecular Characterization and Implication on Post-Surgery Follow-Up of CE Patients Infected with Different Species of the Echinococcus granulosus Complex

“…The currently most promising vaccine candidate EG95-1(G1) [44] differs also from its homologue in the E. canadensis (G6) by few AA variations (5 AA substitutions), but these substitutions result in conformational changes, which lead to a distinct difference in antigenicity between EG95-1G1 and EG95-1G6 [25], [26]. Indeed, antibodies from sheep vaccinated with EG95-1G1 did not react with EG95-1G6 antigen from E. canadensis (G6) [26].…”

“…Variation neutrality was challenged for EG95 genes [22] and theoretically calculated data indicated a genetic polymorphism of the EG95 antigen-coding genes among different genetically characterized strains of E. granulosus [23]. Rojas et al [25], [26] showed that this variability affects the antigenicity of EG95 antigen, by demonstrating that recombinant protein EG95-1G6 ( E. canadensis (G6)) was not recognized by antibodies raised by sheep vaccinated with EG95-1G1. Genetic polymorphism in diagnostic/vaccine candidates was also reported for other parasites including protozoa (e.g.…”