AgB gene expression in Echinococcus s.l. species has been examined suggesting differences between them; this might be relevant for epidemiological investigations intended to discriminate the contribution of distinct E. granulosus s.l. species to human CE. In the larva of E. granulosus s.s. all AgB genes were found to be expressed at mRNA level, even though only AgB8/1 to AgB8/4 protein products have been certainly detected in HF. On the other hand, no evidence of AgB5 expression or of the generation of AgB8/2 and AgB8/5 was achieved in E. canadensis (G6 and G7 genotypes) and E. ortleppi (G5 genotype) metacestode. In particular, AgB2 was proposed to be a pseudogene in E. canadensis.