Variability of the host-protective EG95 vaccine antigen in G6 and G7 genotypic variants

CHOW C; GAUCI CG; VURAL G; JENKINS DJ; HEATH DD; ROSENZVIT MC; HARANDI MF; COWMAN AF; LIGHTOWLERS MW

EXPERIMENTAL PARASITOLOGY

Academic Press

Lugar: United States; Año: 2008 vol. 119 p. 499 - 505

0014-4894

Cystic hydatid disease in humans is caused by the zoonotic parasite Echinococcusgranulosus. As an aid to control transmission of the parasite, a vaccine has been produced forprevention of infection in the parasite’s natural animal intermediate hosts. The vaccineutilizes the recombinant oncosphere protein, EG95. An investigation into the geneticvariability of EG95 was undertaken in this study to assess antigenic variability in E.granulosus. Gene-specific PCR conditions were first established to preferentially amplify theEG95 vaccine-encoding gene (designated eg95-1) from the E. granulosus genome that alsocontains several other EG95-related genes. The optimized PCR conditions were used toamplify eg95-1 from several parasite isolates in order to determine the protein-codingsequence of the gene. An identical eg95-1 gene was amplified from parasites showing a G1 orG2 genotype of E. granulosus. However, from isolates having a G6 or G7 genotype, a genewas amplified which had substantial nucleotide substitutions (encoding amino acidsubstitutions) compared with the eg95 gene family members. The amino acid substitutions ofEG95 in the G6/G7 genotypes may affect the antigenicity/efficacy of the EG95 recombinantantigen against parasites of these genotypes. These findings indicate that characterisation ofeg95 gene family members in other strains/isolates of E. granulosus may provide valuableinformation about the potential for the EG95 hydatid vaccine to be effective against E.granulosus strains other than the G1 genotype.