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- Characterization of C69R variant HBsAg: effect on binding to anti-HBs and the structure of virus-like particles doi link

Auteur(s): Hadiji-Abbes Nadia, Mihoubi Wafa, Martin Fernandez M., Karakasyan-Dia Carole, Frikha Fakher, Gergely C., Jouenne Thierry, Gargouri Ali, Mokdad-Gargouri Raja

(Article) Publié: Archives Of Virology, vol. p.10.1007/s00705-015-2515-y (2015)


Ref HAL: hal-01179792_v1
DOI: 10.1007/s00705-015-2515-y
WoS: 000361817600004
Exporter : BibTex | endNote
5 Citations
Résumé:

Several variants of the major ‘‘a’’ determinant of the HBsAg, the main target of HBV neutralization by antibodies, have been described. However, mutations out- side this region have not been as thoroughly investigated. During the genotyping of HBV from Tunisian patients with chronic hepatitis B, we identified a variant with a C69R substitution in the cytosolic loop of the S protein, resulting in a change in the hydrophobicity profile compared to the wild-type HBsAg. Wild-type and mutant HBsAgs were produced in Saccharomyces cerevisiae and recombinant proteins were tested for their ability to correctly self- assemble into virus-like particles (VLPs), and their ability to bind to HBs antibodies. The C69R substitution resulted in a decrease in binding to commercial anti-HBs antibod- ies, and although the variant appeared to assemble properly into VLPs, the average size of the particles was larger than that of the wild-type HBsAg. Prediction of the tertiary structure of the C69R mutant revealed a change in the first (aa 60-70) and the second loop (aa 110 to 120) compared to the wild-type protein. Furthermore, we showed by an isothermal titration calorimetry assay that the interaction between the wild-type HBsAg and the anti-HBs antibody was exothermic, whereas that with the mutant C69R was endothermic, indicating an effect on the binding affinity.