Mutations in the envelope gene of hepatitis B virus variants co-occurring with antibody to surface antigen in sera from patients with chronic hepatitis B

Three clones of hepatitis B virus (HBV) DNA were propagated from sera of each of five patients with chronic hepatitis B who possessed hepatitis B surface antigen (HBsAg) and antibody to HBsAg in their serum. The clones were sequenced within the envelope gene (the preS1, preS2 regions and the S gene). Clones from four patients had various missense mutations involving codons 124-147 of the S-gene which encode amino acids in the loop structures that form the conformational, common antigenic determinant of HBsAg. Clones from three patients had Asn-130 (Gly in the wild-type), which generated a potential N-glycosylation site, Asn-Thr-Ser, spanning amino acids 130-132 of the S-gene product, In addition, clones from one patient had Arg-145 (Gly in the wild-type), which has been reported in escape mutants of HBV, One of the three clones from another patient had Ser-126 in place of lie or Thr in wild-type HBV, but the remaining two had no mutations known to affect expression of the common determinant of HBsAg. The remaining patient possessed HBsAg of subtype adr and anti-HBs specific for the w determinant. Clones from this patient did not reveal any mutations which are known to affect the common antigenic determinant of HBsAg.