High polymorphism in genes encoding antigen B from human infecting strains of Echinococcus granulosus

KAMENETZKY L.; MUZULIN P. M.; GUTIERREZ A. M.; ANGEL S. O.; ZAHA A.; GUARNERA E. A.; ROSENZVIT M. C.

PARASITOLOGY

Cambridge University Press

Lugar: Reino Unido; Año: 2005 vol. 131 p. 805 - 815

0031-1820

Echinococcus granulosus antigen B (AgB) is encoded by a gene family and is involved in the evasion of the host immuneresponse. E. granulosus exists as a number of strains (G1-G10) that differ in biological characteristics. We used PCR-SSCPfollowed by DNA sequencing to evaluate sequence variation and transcription pro?le of AgB in 5 E. granulosus strains.Twenty-four genomic sequences were isolated and clustered in 3 groups related to 2 of the 5 reported AgB genes. AgB4genes were present in almost all strains, whereas AgB2 were present as functional genes exclusively in G1/G2 cluster, and asnon-functional genes in G5 and the G6/G7 cluster, suggesting inter-strain variation. The AgB transcription patterns,analysed by RT-PCR, showed that AgB2 and AgB4 genes were transcribed in G1, while only the AgB4 gene was transcribedin G7 strain. Cysts from the same strain or cluster shared more genomic and cDNA variants than cysts fromdifferent strain or cluster. The level of nucleotide and deduced amino acid sequence variation observed is higher than thatreported so far for coding genes of other helminths. Neutrality was rejected for AgB2 genes. These data show the geneticpolymorphism of antigen-coding genes among genetically characterized strains of E. granulosus.