Genetic Characterization of Hepatitis B Virus in Peripheral Blood Leukocytes: Evidence for Selection and Compartmentalization of Viral Variants with the Immune Escape G145R Mutation

Abstract

The compartmentalization of viral variants in distinct host tissues is a frequent event in many viral infections. Although hepatitis B virus (HBV) classically is considered hepatotropic, it has strong lymphotropic properties as well. However, unlike other viruses, molecular evolutionary studies to characterize HBV variants in compartments other than hepatocytes or sera have not been performed. The present work attempted to characterize HBV sequences from the peripheral blood leukocytes (PBL) of a large set of subjects, using advanced molecular biology and computational methods. The results of this study revealed the exclusive compartmentalization of HBV subgenotype Ae/A2-specific sequences with a potent immune escape G145R mutation in the PBL of the majority of the subjects. Interestingly, entirely different HBV genotypes/subgenotypes (C, D, or Aa/A1) were found to predominate in the sera of the same study populations. These results suggest that subgenotype Ae/A2 is selectively archived in the PBL, and the high prevalence of G145R indicates high immune pressure and high evolutionary rates of HBV DNA in the PBL. The results are analogous to available literature on the compartmentalization of other viruses. The present work thus provides evidence in favor of the compartment-specific abundance, evolution, and emergence of the potent immune escape mutant. These findings have important implications in the field of HBV molecular epidemiology, transmission, transfusion medicine, organ transplantation, and vaccination strategies.

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

“…Furthermore, a recent report indicated that HBV strains vary in distinct compartments of chronically infected patients, revealing that immune escape sG145R mutants are frequently selected in peripheral blood leukocytes and may then serve as a source of reactivation or transmission (7). It is therefore important to understand the functional implications of immune escape mutations on the replication of HBV strains, especially on strains with common treatment-associated mutations, such as LAM resistance or HBeAg negativity (26).…”

“…Several conditions have been recognized in which HBV escape mutants arise in clinical practice: (i) treatment with anti-HBs immunoglobulin, e.g., after liver transplantation to avoid reinfection of the graft (23,32); (ii) antiviral therapy by itself, as the reading frames of the envelope and polymerase genes overlap and several resistance mutations in the polymerase selected during antiviral therapy simultaneously alter the antigenicity of HBsAg (20,21,31); and (iii) de novo infection of vaccinated individuals with escape mutants (19). Moreover, Datta et al recently reported that HBV variants with the sG145R immune escape mutation may very frequently "hide" in the peripheral blood leukocyte compartment of infected individuals (7).…”

Evaluation of the G145R Mutant of the Hepatitis B Virus as a Minor Strain in Mother-to-Child Transmission

“…It is well known that HBV is lymphotropic as well as hepatotropic. Previous studies reported that G145R mutant was frequently detected in peripheral blood leukocytes from HBsAg-positive and negative patients [39, 40]. Moreover, HBV persisting lymphatic cells contribute to occult HBV infection.…”

Polymorphism of UGT1A1*28 (TA)7 and liver damage in hepatitis B virus-positive patients in Albania

“…To identify HBV genotypes, 10 samples, selected randomly from our population group, were analyzed using a nested polymerase chain reaction (PCR) that was sensitive for the genotyping of integrated HBV in the DNA of leukocytes (Datta et al, 2009). The amplified region contains a sufficient number of sites that vary between the different HBV strains to identify the viral subtype (A-H) using sequencing methods.…”