title: Reverse vaccinology approach identify an Echinococcus granulosus tegumental membrane protein enolase as vaccine candidate.
abstract: Applying reverse vaccinology strategy, we employed a sequence encoding an enolase from Taenia asiatica to search its homolog in the expression sequence tag (EST) database of Echinococcus granulosus and found two EST sequences (Access number: CN653186 and CN649593) of a clone Eg_PSGRS_13B09 from E. granulosus protoscolex full-length cDNA library, which are responding for the 5' and 3' partial cds of E. granulosus enolase, respectively. Primers are designed according to the 5' end and 3'end of the putative encoding sequence to amplify the genomic DNA of E. granulosus strain isolated from sheep in Qinghai province of China by polymerase chain reaction (PCR). A sole product of 1,449 bp in length was obtained, which contains two little introns of 78 bp and 69 bp, respectively. The introns were excised by unsymmetrical PCR with combined flank sequences of introns as primers. The structural, functional, and immunological characteristics of putative amino acid sequence were predicted by bioinformatics analysis. The complete coding sequence was predicted to encode 433 residues and contain a transmembrane region aa(104-124), with the N terminus outside and C terminus inside. The inside part is quite the functional domain. SWISS-MODEL modulated its 3D structure as a barrel which constitutes of alternatively arranged alpha helix-beta sheet, with the key sites such as substrate binding region, active sites, Mg(2+)-binding sites closely located at the center. The protein contains a potential nuclear localization sequence aa(190-199) and several linear B cell epitopes and CTL T cell epitopes, of which the outside epitope aa(49-57) and inside epitope aa(228-236) are facultative T cell and B cell epitope, and the linear B cell epitope aa(206-213) contains the active center site Glu(210), suggesting the putative protein is a potential membrane with strong immunogenicity. The complete cds was expressed in Escherichia coli, and the recombinant protein can be recognized by the serum from patient infected with E. granulosus. Reverse vaccinology process identified E. granulosus tegumental membrane protein enolase as vaccine candidate.
authors.affiliation: Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University Guangzhou, Guangzhou, Guangdong, China.
authors.forename: Wenjia
authors.initials: W
authors.lastname: Gan
authors.forename: Guoxiong
authors.initials: G
authors.lastname: Zhao
authors.forename: Hongxu
authors.initials: H
authors.lastname: Xu
authors.forename: Weihua
authors.initials: W
authors.lastname: Wu
authors.forename: Wuying
authors.initials: W
authors.lastname: Du
authors.forename: Jiang
authors.initials: J
authors.lastname: Huang
authors.forename: Xinbing
authors.initials: X
authors.lastname: Yu
authors.forename: Xuchu
authors.initials: X
authors.lastname: Hu
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D002681:China; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D048209:Echinococcus granulosus / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D004926:Escherichia coli / Q000235:genetics; D020224:Expressed Sequence Tags; D015723:Gene Library; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D010751:Phosphopyruvate Hydratase / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA; D012756:Sheep / Q000469:parasitology*
chemical_list: D000909:Antibodies, Helminth; D018509:DNA, Helminth; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D015801:Helminth Proteins; D008565:Membrane Proteins; D019913:Nuclear Localization Signals; D010751:Phosphopyruvate Hydratase