HBV subgenotypes F1b and F4 replication induces an incomplete autophagic process in hepatocytes: Role of BCP and preCore mutations

Abstract

Hepatitis B virus (HBV) genotypes and mutants have been associated with differences in clinical and virological characteristics. Autophagy is a cellular process that degrades long-lived proteins and damaged organelles. Viruses have evolved mechanisms to alter this process to survive in host cells. In this work, we studied the modulation of autophagy by the replication of HBV subgenotypes F1b and F4, and the naturally occurring mutants BCP and preCore. HBV subgenotypes F1b and F4 replication induced accumulation of autophagosomes in hepatoma cells. However, no autophagic protein degradation was observed, indicating a blockage of autophagic flux at later stages. This inhibition of autophagy flux might be due to an impairment of lysosomal acidification in hepatoma cells. Moreover, HBV-mediated autophagy modulation was independent of the viral subgenotypes and enhanced in viruses with BCP and preCore naturally occurring mutations. These results contribute to understand the mechanisms by which different HBV variants contribute to the pathogenesis of HBV infections. In addition, this study is the first to describe the role that two highly prevalent naturally occurring mutations exert on the modulation of HBV-induced autophagy.

Incomplete autophagy: Trouble is a friend

“…For instance, newly emerged research indicated that SARS‐CoV‐2 induced incomplete autophagy in infected cells and increased the replication efficiency of SARS‐CoV‐2 8 . Similarly, other reports investigated that coxsackievirus A16, PRRSV, Epstein–Barr virus, Porcine tescho virus 2, and HBV infection‐induced incomplete autophagy resulting in increased the virus replication and production 75,127,156–158 . Besides, incomplete autophagy is related to pro‐inflammatory microglia activation following infection of Japanese encephalitis virus 159 .…”

“…8 Similarly, other reports investigated that coxsackievirus A16, PRRSV, Epstein-Barr virus, Porcine tescho virus 2, and HBV infection-induced incomplete autophagy resulting in increased the virus replication and production. 75,127,[156][157][158] Besides, incomplete autophagy is related to pro-inflammatory microglia activation following infection of Japanese encephalitis virus. 159 Therefore, inhibition of incomplete autophagy can effectively inhibit viruses, which is a promising strategy for the development of novel antiviral drugs.…”

Impact of core protein naturally selected mutants associated with HBeAg‐negative status in HBV biosynthesis

“…Transfected cells were lysed in 1X Laemmli buffer, boiled, loaded on 12% sodium dodecyl sulfate (SDS)-polyacrylamide gels, and transferred to polyvinylidene fluoride membranes (Hybond), according to standard protocols. 20 HBc was detected with HBc-170A polyclonal antibody (kindly provided by Dr. Ju-Tao Guo). β-Actin detection was used as intracellular protein loading control.…”