Antiviral resistance mutations potentiate hepatitis B virus immune evasion through disruption of its surface antigen a determinant.
BACKGROUND
The hepatitis B virus (HBV) pol gene overlaps the S gene encoding surface antigen (HBsAg). It has been reported previously that drug-induced changes in HBsAg alter its binding to sera from humans immunized against HBV. We investigate here the changes to specific epitopes in the a determinant (the major target of neutralizing antibody) caused by a number of drug-resistant mutations.


METHODS
Recombinant HBsAgs, produced by transfection of Chinese hamster ovary cells with S gene plasmids into which lamivudine, adefovir and entecavir resistance and common antibody-escape mutations had been introduced, were probed with monoclonal antibodies to epitopes in the first and second loops of the a determinant.


RESULTS
The mutations rtF166L/sF158Y (lamivudine-associated, compensatory) and rtl169T/sF161L (entecavir-associated, primary) acting alone, and the mutations rtV173L/sE164D (lamivudine-associated, compensatory) and rtSilent/sD144E (antibody escape-associated) each when combined with rtM204V/sl195M (lamivudine-associated, primary) led to decreases in antibody reactivity to epitopes in the first or second loop, or in both loops. The rtM204V/sl195M + rtV173L/sE164D mutations yielded an epitope-antibody profile similar to the rtR153Q/sG145R vaccine escape mutant. The rtM204V/sl195M mutation combined with the rtF166L/sF158Y or rtR153Q/sG145R mutation restored reactivity to second-loop epitopes previously abrogated by single mutations.


CONCLUSIONS
Mutations associated with resistance to nucleos(t)ide analogue therapy, singly or in combination with each other or antibody escape-associated mutations, alter HBsAg immunoreactivity through concomitant amino acid substitutions at codons within and downstream of the a determinant. The findings have implications for understanding the native structure of HBsAg, optimizing treatment of chronic hepatitis B and evaluating the success of immunization programmes.
Sloan
Richard D
RD
Virus Reference Division, Centre for Infections, Health Protection Agency, London, UK.
Ijaz
Samreen
S
Moore
Penny L
PL
Harrison
Tim J
TJ
Teo
Chong-Gee
CG
Tedder
Richard S
RS
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D000998:Antiviral Agents / Q000494:pharmacology; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D024921:Drug Resistance, Multiple, Viral / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D015971:Gene Expression Regulation, Enzymologic; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D015684:Gene Products, pol / Q000235:genetics*; D006147:Guanine / Q000031:analogs & derivatives / Q000494:pharmacology; D006510:Hepatitis B Antibodies / Q000276:immunology*; D006514:Hepatitis B Surface Antigens / Q000235:genetics* / Q000276:immunology; D006515:Hepatitis B virus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes / Q000235:genetics*; D019259:Lamivudine / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D063065:Organophosphonates / Q000494:pharmacology; D014162:Transfection
D000911:Antibodies, Monoclonal; D000998:Antiviral Agents; D015684:Gene Products, pol; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D016056:Immunodominant Epitopes; D063065:Organophosphonates; C066027:P protein, Hepatitis B virus; D019259:Lamivudine; C413685:entecavir; D006147:Guanine; C053001:adefovir; D000225:Adenine