Rapid early HDV RNA decline in the peripheral blood but prolonged intrahepatic hepatitis delta antigen persistence after liver transplantation.

BACKGROUND & AIMS: Chronic HDV infection is an inflammatory liver disease and liver transplantation (LTX) remains the only curative treatment option for most patients. The hepatitis D virus (HDV) uses HBsAg as its surface protein, however, it is controversial to what extend HDV may be detected independently of HBsAg in blood and liver after LTX. The aims of this study were to investigate kinetics of HDV RNA and HBsAg early after LTX, to apply the data to a mathematical model and to study long-term persistence of HDV after LTX. METHODS: We retrospectively analyzed 26 patients with chronic hepatitis delta who underwent LTX between 1994 and 2009. Blood samples were obtained every 1-3 days during the first 14 days after LTX. Data were applied to a mathematical model to study viral kinetics. Available liver biopsy samples were stained for HBV and HDV viral antigens and tested for HBV DNA/cccDNA. RESULTS: HBsAg and HDV RNA became negative after a median of 5 days (range 1-13) and 4 days (range 1-10), respectively. Early HDV RNA and HBsAg decline paralleled almost exactly in all patients; however the mathematical model showed a high variability of virion death. HDAg stained positive in transplanted livers in six patients in the absence of liver HBV DNA/cccDNA, serum-HBsAg, and HDV RNA for up to 19 months after LTX. CONCLUSIONS: HDV RNA and HBsAg decline follow almost identical kinetic patterns within the first days after LTX. Nevertheless, intrahepatic latency of HDAg has to be considered when exploring novel concepts to withdraw HBIG.

[The prevalence and clinical characteristics of hepatitis-delta infection in Korea].

BACKGROUND/AIMS: The prevalence of hepatitis delta virus (HDV) infection has been estimated as being approximately 5% among global HBsAg carriers. The anti-delta positive rate in Koreans had been reported as being 0.85% in 1985. While the prevalence of HBV has been decreased from nearly 10% to 5% during the past twenty years, there have been no more studies on the anti-delta prevalence in Koreans. The aim of this study was to estimate the anti-delta prevalence in Koreans and to study the clinical characteristics of anti-delta positive patients in a single center. METHODS: Serum anti-delta was measured in one hundred ninety four HBsAg-positive patients who were admitted to our hospital from February 2003 to August 2003. We checked the genotypes of the HBV in the anti-delta positive patients. The clinical features of the anti-delta positive patients were compared to those clinical features of the anti-delta negative patients from the aspect of age, gender, mode of transmission, the positivity of HBeAg and serum HBV DNA. RESULTS: Serum anti-delta was positive in seven patients among the 194 subjects, giving a 3.6% positive rate. Among these seven patients, six had hepatocellular carcinoma (HCC) and the other one had cholangiocarcinoma. All of the anti-delta positive patients had the C genotype of HBV. The anti-delta positive patients showed significantly suppressed HBV DNA replication compared to the anti-delta negative patients. CONCLUSIONS: In Koreans, anti-delta was positive mainly in HCC patients with an approximate prevalence of 4%, and this rate has not changed much for the past twenty years. HBV DNA replication was suppressed by HDV infection.

Baculovirus as a highly efficient gene delivery vector for the expression of hepatitis delta virus antigens in mammalian cells.

Baculovirus has been employed for a wide variety of applications. In this study, we further expanded the application to the high-level expression of hepatitis delta virus (HDV) antigens and the formation of virus-like particles (VLP) in transduced mammalian cells. To this end, two recombinant baculoviruses were constructed to express large hepatitis delta antigen (L-HDAg) and hepatitis B surface antigen (HBsAg) under mammalian promoters. With a simplified transduction protocol using unconcentrated virus, high transduction efficiencies were achieved in hepatoma cells, in which L-HDAg and HBsAg were expressed abundantly, allowing for easy colorimetric detection in Western blots. L-HDAg alone was nucleus-bound and HBsAg alone was secreted; formation and secretion of HDV-like particles were readily detected upon coexpression, indicating that the baculovirus-expressed proteins were processed correctly as the authentic proteins. Quantitative real-time PCR (Q-PCR) analyses quantitatively revealed that baculovirus transduction was more efficient than plasmid transfection with respect to DNA uptake and DNA transport to the nucleus. Furthermore, superinfection introduced more baculovirus DNA into cells in the long-term culture as revealed by Q-PCR, thereby enhancing and prolonging the expression. In summary, baculovirus transduction can be an attractive method as an alternative to the plasmid transfection commonly employed for HDV research thanks to the significantly higher gene delivery efficiencies as well as the abundant expression and proper processing. Baculovirus can also be envisaged as a useful tool for investigating protein-cell interactions and virus assembly.

Hepatitis delta virus antigen is methylated at arginine residues, and methylation regulates subcellular localization and RNA replication.

Hepatitis delta virus (HDV) contains a circular RNA which encodes a single protein, hepatitis delta antigen (HDAg). HDAg exists in two forms, a small form (S-HDAg) and a large form (L-HDAg). S-HDAg can transactivate HDV RNA replication. Recent studies have shown that posttranslational modifications, such as phosphorylation and acetylation, of S-HDAg can modulate HDV RNA replication. Here we show that S-HDAg can be methylated by protein arginine methyltransferase (PRMT1) in vitro and in vivo. The major methylation site is at arginine-13 (R13), which is in the RGGR motif of an RNA-binding domain. The methylation of S-HDAg is essential for HDV RNA replication, especially for replication of the antigenomic RNA strand to form the genomic RNA strand. An R13A mutation in S-HDAg inhibited HDV RNA replication. The presence of a methylation inhibitor, S-adenosyl-homocysteine, also inhibited HDV RNA replication. We further found that the methylation of S-HDAg affected its subcellular localization. Methylation-defective HDAg lost the ability to form a speckled structure in the nucleus and also permeated into the cytoplasm. These results thus revealed a novel posttranslational modification of HDAg and indicated its importance for HDV RNA replication. This and other results further showed that, unlike replication of the HDV genomic RNA strand, replication of the antigenomic RNA strand requires multiple types of posttranslational modification, including the phosphorylation and methylation of HDAg.

[Differential and diagnostic informative criteria of chronic virus hepatitis D in children]. / Differentsial'no-diagnosticheskie informativnye kriterii khronicheskogo virusnogo gepatita D u detei.

The comparison of clinical and laboratory analyses of HVGD and HVGV gave very informative diagnostic and clinical features in diagnostics of these conditions. They are the following: syndrome of endogenous intoxication, laboratorial data indicating high sensibility to delta antigen, increase in immune cellular value (SD4+, SD8+) and intensity of endogenous intoxication syndrome.