Hepatitis B Virus (HBV) is a small virus whose genome has only four open reading frames. We argue that the simplicity of the virion correlates with a complexity of functions for viral proteins. We focus on the HBV core protein (Cp), a small (183 residue) protein that self-assembles to form the viral capsid. However, its functions are a little more complicated than that. In an infected cell Cp modulates every step of the viral lifecycle. Cp is bound to nuclear viral DNA and affects its epigenetics. Cp correlates with RNA specificity. Cp assembles specifically on a reverse transcriptase-viral RNA complex or, apparently, nothing at all. Indeed Cp has been one of the model systems for investigation of virus self-assembly. Cp participates in regulation of reverse transcription. Cp signals completion of reverse transcription to support virus secretion. Cp carries both nuclear localization signals and HBV surface antigen (HBsAg) binding sites; both of these functions appear to be regulated by contents of the capsid. Cp can be targeted by antivirals -- while self-assembly is the most accessible of Cp activities, we argue that it makes sense to engage the broader spectrum of Cp function. This article forms part of a symposium in Antiviral Research on “From the discovery of the Australia antigen to the development of new curative therapies for hepatitis B: an unfinished story.”

Defining mechanisms of direct-acting antivirals facilitates drug development and our understanding of virus function. Heteroaryldihydropyrimidines (HAPs) inappropriately activate assembly of hepatitis B virus (HBV) core protein (Cp), suppressing formation of virions. We examined a fluorophore-labeled HAP, HAP-TAMRA. HAP-TAMRA induced Cp assembly and also bound pre-assembled capsids. Kinetic and spectroscopic studies imply that HAP-binding sites are usually not available but are bound cooperatively. Using cryo-EM, we observed that HAP-TAMRA asymmetrically deformed capsids, creating a heterogeneous array of sharp angles, flat regions, and outright breaks. To achieve high resolution reconstruction (<4 Å), we introduced a disulfide crosslink that rescued particle symmetry. We deduced that HAP-TAMRA caused quasi-sixfold vertices to become flatter and fivefold more angular. This transition led to asymmetric faceting. That a disordered crosslink could rescue symmetry implies that capsids have tensegrity properties. Capsid distortion and disruption is a new mechanism by which molecules like the HAPs can block HBV infection.

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Hypothesis: Pancreaticoduodenectomy (PD) is a safe procedure for a variety of periampullary conditions. Design: Retrospective review of a prospectively collected database. Setting: Academic tertiary care hospital. Patients: A total of 516 consecutive patients who underwent PD. Main Outcome Measures: Patient outcomes and survival factors. Results: Pathological examination demonstrated 57% periampullary cancers, 22% chronic pancreatitis, 12% cystic neoplasms, 4% islet cell neoplasms, and 5% other. Fiftyone percent of patients underwent pylorus preservation. Median operating time was 5 hours; blood loss, 1300 mL; and transfusion requirement, 1.5 U. Postoperative complications occurred in 43% of patients, including cardiopulmonary events (15%), fistula (9%), delayed gastric emptying (7%), and sepsis (6%). Additional surgery was required in 3% of patients, most commonly because of bleeding. Perioperative mortality was 3.9% overall but only 1.8% in patients with chronic pancreatitis; 25% of patients who died had preoperative complications associated with their periampullary condition. Three-year survival was 15% after resection for pancreatic cancer, 42% for duodenal cancer, 53% for ampullary cancer, and 62% for bile duct cancer. Univariate predictors of long-term survival in patients with periampullary adenocarcinoma included elevated glucose levels, liver function test results, abnormal tumor markers, blood loss, transfusion requirement, type of operation, and pathologic findings (periampullary adenocarcinoma type, differentiation, and margin and node status). Multivariate predictors were serum total bilirubin level, blood loss, operation type, diagnosis, and lymph node status. Conclusions: Pancreaticoduodenectomy continues to be associated with considerable morbidity. With careful patient selection, PD can be performed safely. Long-term survival in patients with periampullary adenocarcinoma can be predicted by preoperative laboratory values, intraoperative factors, and pathologic findings.