There are two hypotheses explaining a fulminant outcome after hepatitis B virus (HBV) infection, both of which may be applicable at the same time: (i) basal core promoter (BCP) mutations increase viral replication, allowing rapid spread of the virus through the liver, and (ii) pre-core (pre-C) mutations abrogating hepatitis B e antigen (HBeAg) synthesis remove its tolerogenic effect, leading to a vigorous immune response. This study investigated the effect of these mutations on virus replication efficiency and HBeAg production. Substitutions A1762T/G1764A and T1753C, C1766T and T1768A in the BCP region, and G1896A and G1899A in the pre-C region, were examined either alone or in combination, using a common genetic background. Huh7 cells were transfected with these constructs and real-time PCR was used to quantify released virion-associated and intracellular HBV DNA, pregenomic RNA and pre-C mRNA. In addition, culture supernatants were tested for hepatitis B surface antigen (HBsAg) and HBeAg. The double BCP mutation (A1762T/G1764A) and the pre-C mutations (G1896A, G1899A), either alone or in combination, had no appreciable effect on the replication capacity of the virus. In contrast, clones with mutations at positions

A patient with agammaglobulinemia developed acute hepatitis that progressed to chronic liver disease with high levels of hepatitis B virus (HBV) DNA in the absence of detectable HBsAg. Sequencing of the a determinant region of HBsAg revealed multiple amino acid substitutions that, unusually, also included a substitution at position 122 that defines subtype specificity. All of these mutations had a profound effect on the antigenicity of this region, which led to the complete failure of variant detection by commercially available routine diagnostic assays or laboratory-based monoclonal antibody assays. CASE REPORTA 50-year-old agammaglobulinemic Greek male patient with a past medical history of multiple respiratory and skin infections presented with acute hepatitis. He had been receiving treatment for polycythemia rubra vera with hydroxyurea during the 2 years prior to admission. In addition, prior to presentation he had been receiving treatment with nimesulide and 32 mg of methylprednisolone daily for 6 and 5 months, respectively, for nonspecific arthritis. The dose of the latter was tapered down during the last month of treatment, and prior to its withdrawal, the patient presented with acute hepatitis with alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and ␥-glutamyl transpeptidase levels of 1,278, 339, 326, and 127 IU/liter, respectively. The total bilirubin level was 1.0 mg/dl, the prothrombin time was 17.7 s, and the international normalized ratio was 1.5. Tests for antinuclear and liver-kidney antimicrosomal antibodies and antibodies against hepatitis A, C, and D viruses (immunoglobulin G [IgG] and IgM) were all negative. The patient tested negative for HBsAg, HBeAg, and anti-HBe and positive for anti-HBc and anti-HBs (sample 1) (AXSYM-MEIA; Abbott Laboratories, Chicago, Ill.). IgM anti-HBc (IMX-MEIA; Abbott Laboratories) and hepatitis C virus RNA were undetectable by PCR. HBsAg remained undetectable in all samples tested subsequently, even when the IMX-MEIA (Abbott Laboratories) and Murex HBsAg kit (version 3; Murex Biotech, Dartford, Kent, United Kingdom) were used. The anti-HBs level was 185 mIU/ml at presentation; this dropped to 72 mIU/ml 5 months later and then stabilized at 92 mIU/ml during the follow-up period. Histological examination of liver biopsy material showed changes consistent with acute hepatitis and signs of reversal to normal. Total immunoglobulin levels were very low at 55 mg/dl (IgG, 33 mg/dl; IgA, 7 mg/dl; IgM, 11 mg/dl). CD4 ϩ and CD8 ϩ counts were increased, while CD4 ϩ / CD8 ϩ ratios of 1 were recorded in peripheral blood. The B-lymphocyte number was reduced. Gamma globulin (Sandoglobulin; Novartis) was first infused at a dose of 400 mg/kg of body weight 1 week after admission, and infusions were repeated every 3 weeks thereafter. Steady state was not achieved, as indicated by the low levels of immunoglobulin detected prior to each infusion. Family contacts were negative for markers of past or present hepatitis B virus (HBV) infection, and H...

Variants of hepatitis B surface antigen have been described in different clinical settings, but their replicative capacity in vitro has remained unexplored. Point mutations leading to sT131I, sK141E, and sG145R amino-acid substitutions were engineered by site-directed mutagenesis into an infectious plasmid clone of the virus. The mutated constructs were transfected into Huh7 cells, and their replication capacity was documented by LightCycler (Roche Diagnostics) measurements of virion-associated hepatitis B virus (HBV) DNA, intracellular relaxed circular double-stranded DNA, and pregenomic RNA. The sT131I and sG145R variants replicated with efficiency equal to that of the wild type, whereas the sK141E variant was replication impaired.Hepatitis B virus (HBV) particles have an outer lipid bilayer envelope into which are inserted the large, middle, and small hepatitis B surface antigen (HBsAg) proteins. All 3 proteins share the group-specific "a" antigenic determinant, a hydrophilic region with a conformational structure that constitutes the main neutralization epitope of the virus [1]. Variants of the virus that have amino acid substitutions in this region have been described in different epidemiological and clinical settings. These variants exhibit altered antigenicity, which causes assays either to fail to detect them or to have greatly reduced sensitivity. Such variants have been described in vaccinees, livertransplant patients who have received monoclonal or polyclonal anti-HBs treatment after transplant, cases of occult infection, and cases of disease reactivation after immunosuppression or cytotoxic drug treatment for malignancies [2].The coexistence of these variants with the presence of antiHBs, which may lead to their partial suppression, raises questions relating to their replication fitness. Because the HBsAg open reading frame overlaps with that of the polymerase, substitutions in the "a" determinant region may have a detrimental effect on polymerase function. The present study aimed to investigate the replication capacity of the following 3 HBsAg variants: the sG145R variant, most often detected in vaccinated children worldwide [3]; the sK141E variant, described in a vaccinated child in Gambia [4]; and the sT131I variant, found in patients with occult infection [5,6]. Two of these substitutions also lead to amino acid changes in the polymerase region. Replicative fitness was assessed by LightCycler (Roche Diagnostics) measurements of HBV-DNA levels in cell culture supernatants and of intracellular levels of replicative intermediates-such as relaxed circular double-stranded (RC-ds) HBV DNA and pregenomic (preG) RNA, the template for negative strand DNA synthesis-and these levels were compared with those found in the wild type (WT). In addition, the levels of preG RNA were compared with those of precore (preC) mRNA, which encodes for the hepatitis B e antigen (HBeAg).Methods. The desired mutations were engineered using the QuikChange Site-Directed Mutagenesis Kit (Stratagene) in accordance with the manuf...

No conclusions concerning the dominance of either genotype or the natural progression or replication rates of HBV could be drawn because the pattern of the genotypes found may have been caused by sampling fluctuations at the time of DNA extraction and cloning as a result of the very low viral loads in the baboon sera.

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