Comprehensive Analysis of Clinically Significant Hepatitis B Virus Mutations in Relation to Genotype, Subgenotype and Geographic Region

Abstract

Hepatitis B virus (HBV) is a highly variable DNA virus due to its unique life cycle, which involves an error-prone reverse transcriptase. The high substitution rate drives the evolution of HBV by generating genetic variants upon which selection operates. HBV mutants with clinical implications have been documented worldwide, indicating the potential for spreading and developing their own epidemiology. However, the prevalence of such mutants among the different HBV genotypes and subgenotypes has not been systematically analyzed. In the current study, we performed large-scale analysis of 6,479 full-length HBV genome sequences from genotypes A-H, with the aim of gaining comprehensive insights into the relationships of relevant mutations associated with immune escape, antiviral resistance and hepatocellular carcinoma (HCC) development with HBV (sub)genotypes and geographic regions. Immune escape mutations were detected in 10.7% of the sequences, the most common being I/T126S (1.8%), G145R (1.2%), M133T (1.2%), and Q129R (1.0%). HBV genotype B showed the highest rate of escape mutations (14.7%) while genotype H had no mutations (P < 0.001). HCC-associated mutations were detected in 33.7% of the sequences, with significantly higher frequency of C1653T, T1753V and A1762T/G1764A in genotype G than C (P < 0.001). The overall frequencies of lamivudine-, telbivudine-, adefovir-, and entecavir-resistant mutants were 7.3, 7.2, 0.5, and 0.2%, respectively, while only 0.05% showed reduced susceptibility to tenofovir. In particular, the highest frequency of lamivudine-resistant mutations was observed in genotype G and the lowest frequency in genotype E (32.5 and 0.3%; P < 0.001). The prevalence of HBV mutants was also biased by geographic location, with North America identified as one of the regions with the highest rates of immune escape, antiviral resistance, and HCC-associated mutants. The collective findings were discussed in light of natural selection and the known characteristics of HBV (sub)genotypes. Our data provide relevant information on the prevalence of clinically relevant HBV mutations, which may contribute to further improvement of diagnostic procedures, immunization programs, therapeutic protocols, and disease prognosis.

Hepatitis B virus genotypes prevalence in patients from hepatology services in Ceará, Brazil

“…In the same sample, the occurrence of an L180M + rtM204V mutation was also observed, which is responsible for the resistance to lamivudine and telbivudine (LdT). Although it is not used in the treatment of HBV patients, the discovery of this mutation corroborates the findings previously described by Araújo et al (2020), who demonstrated that this finding is strongly associated with the G genotype 20 .…”

Molecular Mechanisms during Hepatitis B Infection and the Effects of the Virus Variability

“…Many studies describe the frequency of HBV mutations; a good example is a recent large-scale analysis of HBV genome sequences ( n = 6479, genotypes A–H) in which they report that immune escape mutations were present in 10.7% of the sequences (genotype B showing the highest rate). They also found that hepatocellular carcinoma (HCC) associated mutations were present in 33.7% of the sequences and that the overall frequencies of lamivudine-, telbivudine-, adefovir-, and entecavir-resistant mutants were 7.3%, 7.2%, 0.5%, and 0.2%, respectively, while only 0.05% showed reduced susceptibility to tenofovir [ 9 ].…”

“…A large-scale analysis ( n = 6434), found that immune escape mutations were present in 10.7% of the sequences (I/T126S, 1.8%; G145R, 1.2%; M133T, 1.2%; and Q129R, 1.0%), being G145R the first vaccine escape mutant identified and I/T126S the most frequent [ 9 ]. These mutations have been previously related to vaccine failure [ 170 , 171 ].…”

“…These mutations have been previously related to vaccine failure [ 170 , 171 ]. These studies have identified aa 126 (I126S/N and T126A, 29.63%) and aa 145 (G145R/A, 25.93%) as the hottest mutations post immunization period [ 9 , 170 , 171 ].…”

“…The variability of the HBV genome is driven not only by viral fitness and the lack of corrective activity by the HBVPol, but mutants also result from their selection through pressure exerted by endogenous (host’s immune pressure) and exogenous (antiviral therapy and vaccination) factors [ 8 , 9 ]. It has been found that there is a strong selection in the pre-S1 region, which overlaps with nucleotides encoding the spacer domain of the HBVPol, which is relatively adaptable to non-synonymous mutations.…”