Search results for "Virology"

Reduced hepatitis B virus surface antigen-specific Th1 helper cell frequency of chronic HBV carriers is associated with a failure to produce antigen-…

2000

In chronic hepatitis B virus (HBV) infection weak antiviral immune responses are associated with viral persistence. We studied possible immune deficits underlying the lack of serum antibodies of such patients against the HBV surface antigen (HBsAg) in a novel human/mouse chimeric model. A hepatitis B surface antigen (HBs) vaccination of Balb/c mice engrafted with peripheral blood mononuclear cells (PBMC) of naturally HBV-immunized donors induced high frequencies of human HBsAg-specific B and T helper 1 (Th1) cells. These responses were associated with high serum anti-HBs antibody levels of the subclasses immunoglobulin G1 (IgG1) and IgG2 that are driven by interleukin-2 (IL-2) and interfero…

Enhancement of Gene Expression by Somatic Hybridization with Primary Cells: High-Level Synthesis of the Hepatitis B Surface Antigen in Monkey Vero Ce…

1990

Vero cells transfected with the S gene encoding the surface antigen (HBsAg) of the hepatitis B virus (HBV) synthesize HBsAg at low levels. We have obtained a large increase in S gene expression by somatic hybridization of Vero cells with primary hepatocytes, which are the natural target cells for HBV infection. Fusion with cells other than hepatocytes did not enhance expression of the S gene. The Vero/hepatocyte hybrid clones analyzed are stable and have maintained a high level of HBsAg synthesis over prolonged periods. Hybrid cell lines may be of general interest for the high-level synthesis of proteins using cloned genes.

Polyalbumin receptors, hepatitis B surface antigen (HBsAg), and HBsAg/IgM complexes in HBsAg positive patients with and without delta superinfection.

1985

Receptors for polymerized human albumin are found at high litres during high-level hepatitis B virus (HBV) replication and in small amounts in chronic low-level infection. Complexes between hepatitis B surface antigen (HBsAg) and IgM without specificity for HbsAg are expressed in a pattern similar to that of receptors. Anti-albumin antibodies could be involved in their formation. Delta infection depresses the synthesis of gene products of HBV. To assess whether delta modifies the expression of receptors on HBsAg and the level of HBsAg/IgM complexes, and if anti-albumin antibodies are actually part of the complex, we tested sera from 86 subjects with acute and chronic HBV infection. Our find…

IgM-Antikörper gegen Hepatitis B core-Antigen (anti-HBc IgM) bei “gesunden” HBsAg-Trägern. Eine Verlaufsstudie bei 75 Fällen

1981

In 75 healthy HBsAg carriers with normal liver tissue who were followed over a four years period, anti-HBc IgM was determined by ELISA. 61 HBsAg carriers (81%) were positive for anti-HBc IgM at first investigation. 54 individuals demonstrated persistence of anti-HBc IgM, 7 became anti-HBc IgM-negative within the observation period. 12 persons were persistent anti-HBc IgM-negative, and 2 developed anti-HBc IgM of low quantities. 3 of 4 individuals with HBsAg clearance demonstrated a considerable decrease of anti-HBc IgM concentration. Although signs of liver damage or development of chronic liver diseases were not observed at the time of control biopsy the existence of anti-HBcIgM indicates …

Quantification of CD8+ T lymphocytes responsive to human immunodeficiency virus (HIV) peptide antigens in HIV-infected patients and seronegative pers…

1998

/ T cells responding to HIV-1 peptides were observed in none of 11 HIV- seronegative donors without a history of HIV exposure. ELISPOT assays are relatively fast and easy to perform and appear to reliably detect T cell reactivity due to previous exposure to HIV. These findings support the use of the ELISPOT assay for monitoring T cell responsiveness to HIV peptides. In acute infection with the human immunodeficiency virus We described recently an enzyme-linked immunospot (ELISPOT) assay to detect and quantitate single blood-de- type 1 (HIV-1), initial reduction in virus load is associated with the appearance of a high frequency of antiviral cytotoxic T rived CD8 / T lymphocytes forming tumo…

Perceptions of U = U Among Italian Infectious Diseases Specialists: A Nationwide Survey on Providers' Attitudes Toward the Risk of HIV Transmission i…

2022

This survey aimed to understand how far the Italian infectious diseases (ID) specialists are confident in the "Undetectable = Untransmittable" (U = U) message and translate this concept into clinical practice. An anonymous survey was distributed by e-mail to 286 clinicians to collect their opinions regarding six situations potentially at risk of HIV transmission between virologically suppressed patients and seronegative individuals who possibly require postexposure prophylaxis (PEP). Overall, 51% of ID specialists deemed zero risk of HIV transmission through condomless sex for undetectable patients. This answer was more frequent among HIV specialists (30% vs. 21%, p = .01) and clinicians wo…

Mutations in DNA Binding and Transactivation Domains Affect the Dynamics of Parvovirus NS1 Protein

2013

ABSTRACT The multifunctional replication protein of autonomous parvoviruses, NS1, is vital for viral genome replication and for the control of viral protein production. Two DNA-interacting domains of NS1, the N-terminal and helicase domains, are necessary for these functions. In addition, the N and C termini of NS1 are required for activation of viral promoter P38. By comparison with the structural and biochemical data from other parvoviruses, we identified potential DNA-interacting amino acid residues from canine parvovirus NS1. The role of the identified amino acids in NS1 binding dynamics was studied by mutagenesis, fluorescence recovery after photobleaching, and computer simulations. Mu…

OAM for cure of Helicobacter pylori infection

2000

Immune activation promotes evolutionary conservation of T-cell epitopes in HIV-1.

2013

The immune system should constitute a strong selective pressure promoting viral genetic diversity and evolution. However, HIV shows lower sequence variability at T-cell epitopes than elsewhere in the genome, in contrast with other human RNA viruses. Here, we propose that epitope conservation is a consequence of the particular interactions established between HIV and the immune system. On one hand, epitope recognition triggers an anti-HIV response mediated by cytotoxic T-lymphocytes (CTLs), but on the other hand, activation of CD4(+) helper T lymphocytes (TH cells) promotes HIV replication. Mathematical modeling of these opposite selective forces revealed that selection at the intrapatient l…

Immunological alterations in hepatitis C virus infection

2013

A higher prevalence of immunological processes has recently been reported in patients with hepatitis C virus (HCV) infection, focusing the attention of physicians and researchers on the close association between HCV and immune disorders. HCV lymphotropism represents the most important step in the pathogenesis of virus-related immunological diseases and experimental, virologic, and clinical evidence has demonstrated a trigger role for HCV both in systemic autoimmune diseases, such as rheumatoid arthritis, Sjogren syndrome, hemolytic anemia and severe thrombocytopenia, and in organ-specific autoimmune diseases, such as autoimmune hepatitis, thyroid disorders and diabetes. This review will out…