Pre‐S mutations of hepatitis B virus affect genome replication and expression of surface antigens

• DOI: 10.1111/jgh.12415
• Publication Date: 2013-10-21T11:22:57Z
• Authors: Beom Kyung Kim; Sung Hoon Choi; Sung Hyun Ahn; Ae Ri Chung; Yong Kwang Park; Kwang‐Hyub Han; Seungtaek Kim; Hyon‐Suk Kim; Jeon Han Park; Kyung Sik Kim; Hee Seung Lee; Yong Sang Cho; Kyun‐Hwan Kim; Sang Hoon Ahn
• Keywords: Gene Expression Regulation, Viral; 570; Hepatitis B virus; 0303 health sciences; Hepatitis B Surface Antigens; Pioglitazone; 610; Genome, Viral; Virus Replication; 3. Good health; 03 medical and health sciences; Mutation; Edema; Humans; Protein Precursors; Cells, Cultured

AbstractBackgrounds and AimsIn chronic hepatitis B virus (HBV) infection, quantitative HBV surface antigen (qHBsAg) is useful for monitoring viral replication and treatment responses. We aimed to determine whether pre‐S mutations have any effect on circulating qHBsAg.MethodsPlasmids expressing 1–8 amino acid deletion in pre‐S1 (“pre‐S1Δ1‐8”) and 3‐25 amino acid deletion in pre‐S2 (“pre‐S2Δ3‐25”) were constructed. At 72 h post‐transfection into Huh7 cells, qHBsAg were measured using electrochemiluminescence immunoassay analyzer. To mimic milieus of quasispecies, we co‐transfected either pre‐S1Δ1‐8 or pre‐S2Δ3‐25 with wild type (WT).ResultsPre‐S mutations affected transcription and replication ability of HBV because of altered overlapping polymerase. Compared with WT, extracellular qHBsAg in pre‐S1Δ1‐8 and pre‐S2Δ3‐25 were on average 3.87‐fold higher and 0.92‐fold lower, respectively, whereas intracellular qHBsAg in pre‐S1Δ1‐8 and pre‐S2Δ3‐25 were 0.57‐fold lower and 1.60‐fold higher, respectively. Immunofluorescence staining of cellular HBsAg showed that pre‐S1Δ1‐8 had less staining and that pre‐S2Δ3‐25 had denser staining. As ratios of either pre‐S1Δ1‐8 or pre‐S2Δ3‐25:WT increased from 0:10 to 10:0 gradually, relative extracellular qHBsAg increased from 1.0 to 3.85 in pre‐S1Δ1‐8 co‐transfection, whereas those decreased from 1.0 to 0.88 in pre‐S2Δ3‐25 co‐transfection.ConclusionPre‐S mutations exhibit different phenotypes of genome replication and HBsAg expression according to their locations. Thus, qHBsAg level for diagnosis and prognostification in chronic HBV infection should be used more cautiously, considering emergences of pre‐S deletion mutants.