Key mutations in the C-terminus of the HBV surface glycoprotein correlate with lower HBsAg levels in vivo, hinder HBsAg secretion in vitro and reduce HBsAg structural stability in the setting of HBeAg-negative chronic HBV genotype-D infection

Romina Salpini, Arianna Battisti, Lorenzo Piermatteo, Luca Carioti, Olympia E. Anastasiou, Upkar S. Gill, Domenico Di Carlo, Luna Colagrossi, Leonardo Duca, Ada Bertoli, Katia Yu La Rosa, Lavinia Fabeni, Alessandra Iuvara, Vincenzo Malagnino, Carlotta Cerva, Miriam Lichtner, Claudio M. Mastroianni, Giuseppe Maria De Sanctis, Maurizio Paoloni, Massimo MarignaniCaterina Pasquazzi, Nerio Iapadre, Giustino Parruti, Jacopo Vecchiet, Loredana Sarmati, Massimo Andreoni, Mario Angelico, Sandro Grelli, Patrick T. Kennedy, Jens Verheyen, Stefano Aquaro, Francesca Ceccherini Silberstein, Carlo Federico Perno, Valentina Svicher

Research output: Contribution to journalArticlepeer-review

Abstract

Increasing evidences suggest that HBsAg-production varies across HBV-genotypes. HBsAg C-terminus plays a crucial role for HBsAg-secretion. Here, we evaluate HBsAg-levels in different HBV-genotypes in HBeAg-negative chronic infection, the correlation of specific mutations in HBsAg C-terminus with HBsAg-levels in-vivo, their impact on HBsAg-secretion in-vitro and on structural stability in-silico. HBsAg-levels were investigated in 323 drug-naïve HBeAg-negative patients chronically infected with HBV genotype-D(N = 228), -A(N = 65) and -E(N = 30). Genotype-D was characterized by HBsAg-levels lower than genotype-A and -E (3.3[2.7–3.8]IU/ml; 3.8[3.5–4.2]IU/ml and 3.9[3.7–4.2]IU/ml, P < 0.001). Results confirmed by multivariable analysis correcting for patients’demographics, HBV-DNA, ALT and infection-status. In genotype-D, specific C-terminus mutations (V190A-S204N-Y206C-Y206F-S210N) significantly correlate with HBsAg<1000IU/ml(P-value from <0.001 to 0.04). These mutations lie in divergent pathways involving other HBsAg C-terminus mutations: V190A + F220L (Phi = 0.41, P = 0.003), S204N + L205P (Phi = 0.36, P = 0.005), Y206F + S210R (Phi = 0.47, P < 0.001) and S210N + F220L (Phi = 0.40, P = 0.006). Notably, patients with these mutational pairs present HBsAg-levels 1log lower than patients without them(P-value from 0.003 to 0.02). In-vitro, the above-mentioned mutational pairs determined a significant decrease in HBsAg secretion-efficiency compared to wt(P-value from <0.001 to 0.02). Structurally, these mutational pairs reduced HBsAg C-terminus stability and determined a rearrangement of this domain. In conclusion, HBsAg-levels in genotype-D are significantly lower than in genotype-A and -E in HBeAg-negative patients. In genotype-D, specific mutational clusters in HBsAg C-terminus correlate with lower HBsAg-levels in-vivo, hamper HBsAg-release in-vitro and affect its structural stability, supporting their detrimental role on HBsAg-secretion. In this light, genotypic-testing can be a valuable tool to optimize the clinical interpretation of HBsAg in genotype-D and to provide information on HBV-pathogenicity and disease-progression.

Original languageEnglish
Pages (from-to)928-939
Number of pages12
JournalEmerging Microbes and Infections
Volume9
Issue number1
DOIs
Publication statusE-pub ahead of print - Apr 20 2020

Keywords

  • HBeAg-negative infection
  • HBsAg C-terminus
  • HBsAg levels
  • HBsAg mutations
  • HBV genotypes

ASJC Scopus subject areas

  • Parasitology
  • Epidemiology
  • Microbiology
  • Immunology
  • Drug Discovery
  • Virology
  • Infectious Diseases

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