GENOMIC AND EXPRESSION ANALYSIS OF A MAJOR SECRETED ANTIGEN OF ECHINOCOCCUS GRANULOSUS: THE ANTIGEN B

LAURA KAMENETZKY; PATRICIA MUZULIN; FEDERICO CAMICIA; ARIANA GUTIERREZ; HUGO LUJÁN; MARA ROSENZVIT

Escocia

Congreso; XI International Congress of Parasitology; 2006

XI International Congress of Parasitology

The cestode E. granulosus, responsible for the worldwide extended zoonosis cystic hydatid disease, exists as a number of strains adapted to different intermediate hosts. E. granulosus antigen B (AgB) is expressed in the larval stage and secreted to the host milieu. It is used in diagnosis and was involved in the modulation of the host immune response. E. granulosus AgB is a gene family composed of at least five members (AgB1-AgB5), sharing an amino acid identity of 47-98%. We used PCR-SSCP followed by sequencing to do a genomic and expression analysis of AgB in five human infecting strains. We also studied AgB expression in individual protoscoleces of the same cyst and other life cycle stages of E. granulosus sheep strain by RT-PCR with subunit-specific primers. Genomic and transcriptional differences among E. granulosus strains were detected. In sheep strain all the AgB subunits were found. However, in cattle, camel and pig strains, AgB2 genes were detected as pseudogenes and AgB5 was not detected at the genomic or the RNA levels. Also, differential expression of AgB subunits was found among protoscoleces of the same cyst. It was also found that some of the AgB subunits were not detected in adult worms and oncospheres. Immunohystochemical experiments with subunit-specific antibodies showed that some of them have different localization patterns in protoscolex, suggesting different functions for the AgB subunits. Different expression of AgB genes may be related to the establishment and/or survival of the parasite in the host.