title: Genetic variability of the 18 kDa/HP6 protective antigen in Taenia saginata and Taenia asiatica: implications for vaccine development.
abstract: Genomic characterization of the genes encoding the Taenia 18 kDa/HP6 protective antigens was carried out for Taenia saginata and T. asiatica using 42 taeniid isolates comprising 23 samples of T. saginata, 13 samples of T. asiatica and 6 samples of T. solium. The corresponding sequences from all taeniid isolates were PCR-amplified with specific primers and then sequenced. All the genes, and other described taeniid gene homologues, had the same genomic structure. Surprisingly, the T. saginata TSA18 gene showed nucleotide variability within the 23 samples analyzed. This resulted in two distinct genotypes with 96% DNA sequence similarity and deduced amino acid sequences with 21 substitutions, mainly located in the second exon which contains the fibronectin type III domain. In regards to T. asiatica, the 18 kDa gene (TASI18) was very similar to the T. saginata antigen homologues, both at the DNA and deduced amino acid sequence levels, and the TSOL18 gene was conserved among T. solium isolates as previously described. The implications of these findings on the future development of taeniid vaccines are discussed.
authors.affiliation: Parasitology Department, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: González
authors.forename: Raquel
authors.initials: R
authors.lastname: Ramiro
authors.forename: Luz
authors.initials: L
authors.lastname: García
authors.forename: R Michael E
authors.initials: RM
authors.lastname: Parkhouse
authors.forename: Donald P
authors.initials: DP
authors.lastname: McManus
authors.forename: Teresa
authors.initials: T
authors.lastname: Gárate
mesh_terms: D000352:Africa, Northern; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000947:Antigens, Helminth / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D001208:Asia; D002417:Cattle; D017931:DNA Primers / Q000737:chemistry; D018509:DNA, Helminth / Q000235:genetics / Q000276:immunology; D005060:Europe; D005091:Exons; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation / Q000276:immunology; D006801:Humans; D007843:Latin America; D008969:Molecular Sequence Data; D058974:Phylogeography; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D012689:Sequence Homology, Nucleic Acid; D013552:Swine; D041202:Taenia saginata / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D041201:Taenia solium / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D013622:Taeniasis / Q000235:genetics / Q000276:immunology / Q000517:prevention & control; D014614:Vaccines, Synthetic / Q000096:biosynthesis
chemical_list: D000947:Antigens, Helminth; D017931:DNA Primers; D018509:DNA, Helminth; D005353:Fibronectins; C464926:HP6 protein, Taenia saginata; D014614:Vaccines, Synthetic