title: Characterization of the gene family encoding a host-protective antigen of the tapeworm Taenia ovis.
abstract: Genomic structure has been determined for a gene encoding a host-protective antigen of the parasitic platyhelminth Taenia ovis. An incomplete cDNA, known as 45W, encodes the protective antigen. Southern hybridisation experiments using 45W cDNA as a probe, revealed that the 45W gene was a member of a multigene family. Differential Southern hybridisation and rapid amplification of cDNA end (RACE) experiments were used to characterise the related genes, allowing the full-length coding region of the 45W encoded antigen to be determined. The gene family comprises a minimum of four members per haploid genome with each member showing varying degrees of 5' and 3' homology with respect to the 45W cDNA. A close homologue of the 45W gene, designated 45S, differed from 45W at 11 of 985 nt comprising the full-length mRNA. Sequencing of several independent RACE products for both 45W and 45S identified a cDNA which may be a product of homologous recombination between these genes, suggesting that the two genes may be alleles. Homologous recombination in genes which encode a host protective antigen such as 45W would provide a mechanism by which antigenic variants could arise.
authors.affiliation: University of Melbourne, Veterinary Clinical Centre, Werribee, Victoria, Australia.
authors.forename: J G
authors.initials: JG
authors.lastname: Waterkeyn
authors.forename: M W
authors.initials: MW
authors.lastname: Lightowlers
authors.forename: R
authors.initials: R
authors.lastname: Coppel
authors.forename: A F
authors.initials: AF
authors.lastname: Cowman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000940:Antigenic Variation; D000947:Antigens, Helminth / Q000235:genetics*; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D018509:DNA, Helminth / Q000235:genetics; D017238:Genes, Helminth; D008969:Molecular Sequence Data; D005810:Multigene Family; D018510:RNA, Helminth / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013621:Taenia / Q000235:genetics* / Q000276:immunology*
chemical_list: D000947:Antigens, Helminth; D018076:DNA, Complementary; D018509:DNA, Helminth; D018510:RNA, Helminth; D012333:RNA, Messenger