Résumé
Cytotoxic T cells (CTLs) play a key role in the control of Hepatitis B virus (HBV) infection and viral clearance. However, most of identified CTL epitopes are derived from HBV of genotypes A and D, and few have been defined in virus of genotypes B and C which are more prevalent in Asia. As HBV core protein (HBc) is the most conservative and immunogenic component, in this study we used an overlapping 9-mer peptide pool covering HBc to screen and identify specific CTL epitopes. An unconventional HLA-A2-restricted epitope HBc141-149 was discovered and structurally characterized by crystallization analysis. The immunogenicity and anti-HBV activity were further determined in HBV and HLA-A2 transgenic mice. Finally, we show that mutations in HBc141-149 epitope are associated with viral parameters and disease progression in HBV infected patients. Our data therefore provide insights into the structure characteristics of this unconventional epitope binding to MHC-I molecules, as well as epitope specific CTL activity that orchestrate T cell response and immune evasion in HBV infected patients.
Sujets)
Adulte , Animaux , Femelle , Humains , Mâle , Souris , Adulte d'âge moyen , Séquence d'acides aminés , Sites de fixation , Épitopes , Chimie , Allergie et immunologie , Métabolisme , Génotype , Cellules HEK293 , Antigène HLA-A2 , Métabolisme , Antigènes de la nucléocapside du virus de l'hépatite virale B , Chimie , Allergie et immunologie , Métabolisme , Virus de l'hépatite B , Génétique , Métabolisme , Liaison hydrogène , Souris de lignée BALB C , Souris transgéniques , Simulation de dynamique moléculaire , Mutation , Liaison aux protéines , Structure tertiaire des protéines , Lymphocytes T cytotoxiques , Allergie et immunologie , MétabolismeRésumé
Secretory anti-gp96 scFv fragment was expressed in Pichia pastoris to obtain a small molecule antibody that specifically recognizes heat shock protein gp96. The gp96-scFv fragment gene was synthesized and cloned to Pichia pastoris expression plasmid pPICZa-A. Pichia pastoris X33 was electroporated with the linearized recombinant expression vector, and expression of gp96-scFv fragment was induced by methanol. The His-tagged recombinant protein was then purified by affinity chromatography and analyzed with SDS-PAGE and Western blotting assays. The biological activities of recombinant gp96-scFv fragment were determined by Western blotting, Immunofluorescence, ELISA and FACS assays. The gp96-scFv fragment was expressed successfully in Pichia pastoris. About 50 mg of recombinant protein could be purified from 1 liter of the Pichia pastoris culture supernatant. Its molecular weight was about 15 kDa. The gp96-scFv fragment could specifically bind to gp96 protein by Western blotting, immunofluorescence, ELISA and FACS analyses. Pichia pastoris-expressed gp96-scFv fragment specifically recognizes gp96 protein, which could be used for Western blotting, Immunofluorescence, ELISA and FACS analyses.