Abstract
Twenty-seven PCR-derived antigen B (AgB) nucleotide sequences from four Echinococcus species ( Echinococcus granulosus, Echinococcus multilocularis, Echinococcus oligarthrus and Echinococcus vogeli) were aligned with 78 already published sequences, to generate a maximum likelihood phylogeny of the AgB multigene family. The phylogenetic analysis confirms that the family is constituted by four groups of genes present in each one of the four species ( AgB1, AgB2, AgB3 and AgB4), and suggests that it originated by ancient duplication events preceding speciation within the genus. AgB5 sequences, which had been formerly suggested to correspond to a putatively new AgB subunit, cluster with AgB3. Likelihood tests suggest that AgB gene evolution may have been driven by heterogeneous selection pressures acting on particular AgB1, AgB3 and AgB4 codons. No selection is detected in AgB2. We discuss implications of our findings in terms of AgB biology and its use as a diagnostic tool.
Highlights
Antigen B (AgB), the major antigen of Echinococcus granulosus, which causes the cystic hydatid disease, is a 120– 160 kDa lipoprotein composed of heterogeneous multimers of 8-kDa subunits encoded by a multigene family
The nucleotide sequences identified with a letter followed by a number are the alleles found in our previous study of E. granulosus AgB variation (Haag et al, 2004), which were obtained from only three protoscoleces from a single metacestode; those shown in bold letters are sequences obtained in the present study
All E. granulosus cervid strain and Echinococcus oligarthrus sequences from the AgB3 clade are clustered with the AgB5 (Q) alleles, and not with those corresponding to the already known E. granulosus AgB3 subunit (R alleles)
Summary
Antigen B (AgB), the major antigen of Echinococcus granulosus, which causes the cystic hydatid disease, is a 120– 160 kDa lipoprotein composed of heterogeneous multimers of 8-kDa subunits encoded by a multigene family. Four AgB genes have been characterized, AgB1, AgB2, AgB3 and AgB4 (Shepherd et al, 1991; Fernandez et al, 1996; Chemale et al, 2001; Arend et al, 2004), each encoding a related, but distinct AgB subunit. The Echinococcus AgB is predicted to be alpha helix-rich (Gonzalez-Sapienza and Cachau, 2003), but its binding properties to hydrophobic compounds and its polymeric nature suggest a distinct biological role in relation to the parasite LBPs
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
