Expression of HBsAg variants to improve the efficacy of the current anti-hepatitis B vaccine

PERAZZO P; EGUIBAR N; SORDELLI A; RODRIGUEZ DEL VALLE N; GALLEGO M; MOLINA R; SAQUIN J; NUDEL C; GONZALEZ R; NUSBLAT A; CUESTAS ML

Congreso; LI Reunión SAIB; 2015

Introduction: Cocirculation of HBsAg and neutralizing anti-HBsantibodies in patients with adequate active/passive immunization or during thenatural course of infection is a problem of health concern. The most widelyreported S-escape mutants are D144A, G145R and those at cysteines. All anti-HBVvaccines available are only composed of wild-type (wt) HBsAg; the S-escapemutants described to date in the world are not included. Some of them may alsoescape immune detection by some commercial kits used in the diagnosis of HBVinfection and in the screenings of blood donors.Aims: To analyze the effect of S mutants at various positions (eg,C107R,D144A,G145R)in relation to the interaction with anti-HBs antibodies from wt strains.Methods: Wt and mutant S genes were cloned into the expression vector pPICZa andtransformed into Pichia pastoris X-33. For detection of HBsAg, commercial ELISAassays were performed. VLPs were characterized and reactivity of wt and mutantHBsAg was assayed in vitro (TEM and DLS) and in silico.Results: High expression levels were obtained, and the resulting VLPs had asize of about 20 nm. Reactivity with anti-HBs antibodies was variable.Conclusions: This may lead to the development of a newanti-HBV vaccine covering such escape mutants, as well as for the developmentof diagnostic tools needed - and still not available, for their detection, assome of them may escape their detection.