Search results for "Virology"

Kinetics of hepatitis B surface antigen-specific immune responses in acute and chronic hepatitis B or After HBs vaccination: Stimulation of thein vit…

1999

Because cellular and humoral immune responses against the hepatitis B virus (HBV) surface antigen (HBs) might be crucial to overcome HBV infection, HBs-specific B- and T-cell responses of HBV patients and HBs vaccine recipients were analyzed quantitatively and functionally. In patients with acute hepatitis B (AHB), transient high anti-HBs-secreting B-cell frequencies were observed early after clinical onset, whereas 1 patient who probably developed chronic infection and chronic HBV carriers had absent or weak B- and T-cell responses. In HBs vaccine recipients, maximal HBs-specific B- and T-cell responses were detected after the first injection that decreased gradually before anti-HBs antibo…

Clinical and immunological efficacy of intradermal vaccine plus lamivudine with or without interleukin-2 in patients with chronic hepatitis B

2002

To evaluate therapeutic immunostimulation nine chronic hepatitis B patients received six monthly intradermal vaccinations with HBsAg in combination with daily lamivudine. Another five patients received six doses of the vaccine and daily lamivudine together with daily Interleukin-2 (IL-2) s.c. within 3 months in an open-labeled trial. Clinical efficacy was assessed by alanine transaminase levels and HBV serology. The induction of specific T and B cell responses was analyzed serially by 3H-thymidine uptake, ELISA and ELISPOT assays. After the therapy was stopped, seven of nine vaccine/lamivudine and two of five vaccine/lamivudine/IL-2 recipients did not have detectable HBV DNA. Four complete …

Endemic hepatitis C virus infection in a Sicilian town: Further evidence for iatrogenic transmission

2002

The prevalence of and risk factors for HCV and HBV infections in the general population and the predictive value of ALT screening in identifying anti-HCV positive subjects have been evaluated in a small Sicilian town. A random 1:4 sampling from the census of the general population was performed. Anti-HCV, HCV-RNA, HCV genotype, HBsAg, and anti-HBc were tested. The linkage between HCV infection and potential risk factors was evaluated by multiple logistic regression analysis. Among 721 subjects studied, 75 (10.4%) were anti-HCV positive. The HCV infection rate increased from 0.4% in subjects 10–29 years of age to 34% in those > 60 years of age. Among the 75 anti-HCV positive subjects, 66.7% …

Sequence-Specific Repression of Cotranslational Translocation of the Hepatitis B Virus Envelope Proteins Coincides with Binding of Heat Shock Protein…

1997

AbstractThe large L envelope protein of the hepatitis B virus has the peculiar capacity to adopt two transmembrane topologies. The N-terminal preS domain of L initially remains in the cytosol while the S domain is cotranslationally inserted into the endoplasmic reticulum membrane. The preS region of about half of the L molecules is posttranslationally translocated to the lumenal space. We now demonstrate that the repression of cotranslational translocation of preS is conferred by a preS1-specific sequence. By analysis of L deletion mutants, the cytosolic anchorage determinant was mapped to amino acid sequence 70 to 94 of L. The intrinsic potential of this determinant to suppress cotranslati…

Hepatitis B virus with antigenically altered hepatitis B surface antigen is selected by high-dose hepatitis B immune globulin after liver transplanta…

1998

“Escape” variants of hepatitis B virus (HBV) can cause infection despite previous immunization. These viruses show alterations of the immunogenic major hydrophilic loop of the HBV small surface protein (s-protein). We studied whether HBV “escape” variants were selected in patients with graft infection after liver transplantation for HBV-related diseases who received passive immunoprophylaxis with high-dose polyclonal hepatitis B hyperimmune globulin (HBIG). For that, pre- and posttransplantation sera of 34 patients were analyzed for the occurence of HBV S-gene variants. In addition, binding of in vitro–translated variant s-proteins to HBIG was studied. Variants with exchanges of amino acid …

Mutation specific PCR and direct solid phase sequencing assay for the detection of hepatitis B virus pre-C/C mutants in anti-HBe-positive, chronic he…

1994

Sequence analysis of the HBV DNA from patients with anti-HBe+, chronic hepatitis B revealed that the lack of HBeAg is mostly due to a single GA transition at nucleotide position 1896, resulting in a translational stop codon. A point mutation-specific polymerase chain reaction (msPCR) for the detection of this genetic variant was established. Two serologically defined groups of patients with symptomatic chronic hepatitis B (HBeAg+ n = 14, anti-HBe+ n = 11) were included in this study. Viral DNA from 43 sera (26 eAg+/17 anti-HBe+) was amplified twice, using two different sets of PCR primers. Each set contained the same — strand primer, but the + strand primers differed at their 3′-end, thus b…

Stop codon insertion restores the particle formation ability of hepatitis B virus core-hantavirus nucleocapsid protein fusions.

2003

In recent years, epitopes of various origin have been inserted into the core protein of hepatitis B virus (HBc), allowing the formation of chimeric HBc particles. Although the C-terminus of a C-terminally truncated HBc (HBcΔ) tolerates the insertion of extended foreign sequences, the insertion capacity is still a limiting factor for the construction of multivalent vaccines. Previously, we described a new system to generate HBcΔ mosaic particles based on a read-through mechanism in an <i>Escherichia coli</i> suppressor strain [J Gen Virol 1997;78:2049–2053]. Those mosaic particles allowed the insertion of a 114-amino acid (aa)-long segment of a Puumala hantavirus (PUUV) nucleocap…

Virus replication and virion export in X-deficient hepatitis B virus transgenic mice

2002

The function of the X protein (pX) in the replication cycle of mammalian hepadnaviruses is enigmatic. Using tissue culture experiments it has been shown that the X gene product is not central to hepatitis B virus (HBV) replication and virion export. However, at present it is still unclear whether this also applies to the in vivo situation. Using a terminally redundant X-deficient HBV DNA construct, transgenic mice were established that exhibited high-level expression of the viral core protein in liver and kidneys. Importantly, replicative DNA intermediates and mature viral genomes could be detected in the liver and serum of these mice, respectively. These findings indicate that, in the in v…

The significance of the pre-S region of the hepatitis B virus

1986

Molecular hybridization techniques in current diagnosis of chronic hepatitis B in childhood.

1992

Following the cloning and sequencing of the hepatitis B virus genome, molecular hybridization techniques have been established to detect hepatitis B virus (HBV) DNA in serum and liver tissue. Analyses can be performed by dot blot, Southern blot and in situ hybridization. HBV DNA is regarded to be the most sensitive marker of viral replication and infectivity which was previously related to the presence of hepatitis B e antigen in serum and hepatitis B core antigen in liver cells. In liver tissue different molecular patterns can be recognized as free viral DNA and integrated sequences. Furthermore, introduction of the polymerase chain reaction allows the detection of very small amounts of vi…