Differential Impact of Immune Escape Mutations G145R and P120T on the Replication of Lamivudine-Resistant Hepatitis B Virus e Antigen-Positive and -Negative Strains

Abstract

Immune escape variants of the hepatitis B virus (HBV) represent an emerging clinical challenge, because they can be associated with vaccine escape, HBV reactivation, and failure of diagnostic tests. Recent data suggest a preferential selection of immune escape mutants in distinct peripheral blood leukocyte compartments of infected individuals. We therefore systematically analyzed the functional impact of the most prevalent immune escape variants, the sG145R and sP120T mutants, on the viral replication efficacy and antiviral drug susceptibility of common treatment-associated mutants with resistance to lamivudine (LAM) and/or HBeAg negativity. Replication-competent HBV strains with sG145R or sP120T and LAM resistance (rtM204I or rtL180M/rtM204V) were generated on an HBeAg-positive and an HBeAg-negative background with precore (PC) and basal core promoter (BCP) mutants. The sG145R mutation strongly reduced HBsAg levels and was able to fully restore the impaired replication of LAM-resistant HBV mutants to the levels of wild-type HBV, and PC or BCP mutations further enhanced viral replication. Although the sP120T substitution also impaired HBsAg secretion, it did not enhance the replication of LAM-resistant clones. However, the concomitant occurrence of HBeAg negativity (PC/BCP), sP120T, and LAM resistance resulted in the restoration of replication to levels of wild-type HBV. In all clones with combined immune escape and LAM resistance mutations, the nucleotide analogues adefovir and tenofovir remained effective in suppressing viral replication in vitro. These findings reveal the differential impact of immune escape variants on the replication and drug susceptibility of complex HBV mutants, supporting the need of close surveillance and treatment adjustment in response to the selection of distinct mutational patterns.

Clinical features and viral quasispecies characteristics associated with infection by the hepatitis B virus G145R immune escape mutant

“…The most frequently observed mutations in the S region were located at aa 126, 129, 130, 133, 145 and 181. 2, 6, 22 The G145R mutation in the MHR, which is one of the most prevalent immune escape mutations, can impair HBsAg secretion 28 and has been reported in patients with advanced liver diseases and even liver cancer. 15 In addition, the Q181R mutation has been recently reported in a new vaccine escape mutant.…”

Naturally Occurring Mutations in Large Surface Genes Related to Occult Infection of Hepatitis B Virus Genotype C

“…Mutations in major hydrophilic regions (MHR), particularly the “a” determinant, are known to be associated with occult infection or the generation of vaccine escape variants due to the reduced binding affinity between the HBsAg and the antibody to HBsAg [37]–[40]. Among the MHR mutations related to vaccine escape, the mutation from glycine to arginine in the 145 th codon of HBsAg, known as G145R, has been most frequently encountered worldwide [37], [38]. However, the G145R mutation was found only in one patient in our cohort (KU-II-28) (Table S1).…”

Molecular identification of hepatitis B virus genotypes/subgenotypes: Revised classification hurdles and updated resolutions

“…In Bolivia, the exchange of native HBV subgenotype F4 and exotic ones (subgenotypes B2 and C2) between Bolivian and Japanese immigrants was clearly demonstrated by phylogenetic analysis [151] . Interestingly, the exotic strains have different mutational patterns in different ORFs of HBV [123] , which would have a different impact on the course of infection, therapeutic, diagnostic and prophylactic measures [152,153] .…”