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

KAMENETZKY, L.; MUZULIN, P.; GUTIERREZ, A.; ANGEL, S.; ZAHA, A.; GUARNERA, E.; MARA CECILIA ROSENZVIT

PARASITOLOGY

Cambridge University Press.

Lugar: Cambridge, Inglaterra; Año: 2005 vol. 131 p. 805 - 816

0031-1820

Echinococcus granulosus antigen B (AgB) is encoded by a gene family and isinvolved in the evasion of the host immune response. E. granulosus exists as anumber of strains (G1-G10) that differ in biological characteristics. We usedPCR-SSCP followed by DNA sequencing to evaluate sequence variation andtranscription profile of AgB in 5 E. granulosus strains. Twenty-four genomicsequences were isolated and clustered in 3 groups related to 2 of the 5 reportedAgB genes. AgB4 genes were present in almost all strains, whereas AgB2 werepresent as functional genes exclusively in G1/G2 cluster, and as non-functionalgenes in G5 and the G6/G7 cluster, suggesting inter-strain variation. The AgBtranscription patterns, analysed by RT-PCR, showed that AgB2 and AgB4 genes weretranscribed in G1, while only the AgB4 gene was transcribed in G7 strain. Cystsfrom the same strain or cluster shared more genomic and cDNA variants than cystsfrom different strain or cluster. The level of nucleotide and deduced amino acidsequence variation observed is higher than that reported so far for coding genesof other helminths. Neutrality was rejected for AgB2 genes. These data show thegenetic polymorphism of antigen-coding genes among genetically characterizedstrains of E. granulosus.