Candidate epistatic mutation clusters in occult hepatitis B virus genotype D: a critical narrative review of the evidence gap and a proposed testable framework
Narrative review reveals an evidence gap for candidate epistatic mutation clusters in occult hepatitis B genotype D, highlighting the need for mechanistic and functional validation.
Key Points
To critically assess current evidence on whether epistatic surface-protein mutation clusters drive occult hepatitis B infection in genotype D and propose a framework to test this mechanism.
Conducted a critical narrative review of genomic, structural, and clinical evidence regarding hepatitis B surface antigen (HBsAg) mutations in genotype D.
Applied a four-tier evidence hierarchy classifying data into co-occurrence, phylogenetically corrected covariation, experimental mutant reconstruction, and mechanistic validation.
Published evidence on genotype D HBsAg mutation clusters reaches Level 1–2 at most, with no direct Level 3 site-directed reconstruction experiments comparing candidate clusters to constituent single mutants.
Cryo-electron microscopy structures of HBsAg subviral particles currently lack the resolution required to assess mutation-induced conformational shifts in the critical 'a' determinant loops.
Direct empirical evidence linking HIV or hepatitis C virus coinfections to the selection of epistatic mutation clusters in genotype D is currently lacking.