Instructions: Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Input: 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.', '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.', '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.
Output:
Do antiviral resistance mutations potentiate hepatitis B virus immune evasion through disruption of its surface antigen a determinant?