Search results for "Virology"

Alix regulates egress of hepatitis B virus naked capsid particles in an ESCRT-independent manner

2010

Hepatitis B virus (HBV) is an enveloped DNA virus that exploits the endosomal sorting complexes required for transport (ESCRT) pathway for budding. In addition to infectious particles, HBV-replicating cells release non-enveloped (nucleo)capsids, but their functional implication and pathways of release are unclear. Here, we focused on the molecular mechanisms and found that the sole expression of the HBV core protein is sufficient for capsid release. Unexpectedly, released capsids are devoid of a detectable membrane bilayer, implicating a non-vesicular exocytosis process. Unlike virions, naked capsid budding does not require the ESCRT machinery. Rather, we identified Alix, a multifunctional …

A membrane-destabilizing peptide in capsid protein L2 is required for egress of papillomavirus genomes from endosomes

2005

ABSTRACT Papillomaviruses are internalized via clathrin-dependent endocytosis. However, the mechanism by which viral genomes pass endosomal membranes has not been elucidated. In this report we show that the minor capsid protein L2 is required for egress of viral genomes from endosomes but not for initial uptake and uncoating and that a 23-amino-acid peptide at the C terminus of L2 is necessary for this function. Pseudogenomes encapsidated by L1 and L2 lacking this peptide accumulated in vesicular compartments similar to that observed with L1-only viral particles, and these mutant pseudoviruses were noninfectious. This L2 peptide displayed strong membrane-disrupting activity, induced cytolys…

The endocytic trafficking pathway of oncogenic papillomaviruses

2019

Over the last two decades many host cell proteins have been described to be involved in the process of infectious entry of oncogenic human papillomaviruses (HPV). After initial binding and priming of the capsid, a sequence of events on the cell surface precedes the formation of the HPV entry platform. It has been shown that the virus-associated entry complex consists of membrane organizers, tetraspanins CD151 and CD63, and their associated partner proteins such as integrins, growth factor receptors, and the annexin A2 heterotetramer. Further recruitment of cytoplasmic factors such as the obscurin-like protein 1 and actin results in a non-canonical clathrin-independent endocytosis of the vir…

Protease inhibitor atazanavir induces leukocyte-endothelial cell interactions in the microvasculature

2008

Characterization of a novel population of low-density granulocytes associated with disease severity in HIV-1 infection

2012

The mechanisms resulting in progressive immune dysfunction during the chronic phase of HIV infection are not fully understood. We have previously shown that arginase, an enzyme with potent immunosuppressive properties, is increased in HIV seropositive (HIV+) patients with low CD4(+) T cell counts. Here we show that the cells expressing arginase in peripheral blood mononuclear cells of HIV+ patients are low-density granulocytes (LDGs) and that whereas these cells have a similar morphology to normal-density granulocyte, they are phenotypically different. Importantly, our results reveal that increased frequencies of LDGs correlate with disease severity in HIV+ patients.

Analysis of the TK enzyme complex induced by HSV types 1 and 2 by means of isoelectric focusing and polyacrylamide gel electrophoresis.

1982

Recently we have described that the Herpes simplex virus (HSV)-induced thymidine kinase (TK) induces AMP- and ADP-dThd-5'-phosphotransferase activities. We now demonstrate the heterogeneity of the described activities in isoelectric focusing experiments and polyacrylamide gel electrophoresis. A TK--mutant of HSV type 1 fails to induce these activities. The activities of the type 1 enzyme complex was neutralized by an anti-HSV-serum. The TK-enzyme complex expressed in LTK--cells transformed to a TK+-phenotype by sheared HSV-1 DNA was compared with the wild type TK complex in isoelectric focusing experiments. Additionally we demonstrate that the HSV type 1 enzyme complex has thymidylate kinas…

Evaluation of a multiplex reverse transcriptase PCR ELISA for the detection of nine respiratory tract pathogens.

2003

A multiplex reverse transcription (RT) polymerase chain reaction combined with a microwell hybridization assay (m-RT-PCR-ELISA) was previously developed to detect nine different microorganisms: enterovirus (EV), influenza virus type A (IVA) and type B (IVB), respiratory syncytial virus (RSV), parainfluenzavirus type 1 (PIV1) and type 3 (PIV3), adenovirus (AV), Mycoplasma pneumoniae (Mpn), Chlamydia pneumoniae (Cpn) in a single test. These organisms do not usually colonize the respiratory tract of humans, but, if present, it may be assumed they are involved in respiratory disease.The m-RT-PCR-ELISA was tested on (i) culture supernatants of unknown contents, (ii) by determining the analytical…

An enzyme-linked immunosorbent assay for detection of Vibrio vulnificus biotype 2: development and field studies.

1997

Vibrio vulnificus biotype 2 is a primary eel pathogen which constitutes a lipopolysaccharide (LPS)-based homogeneous O serogroup within the species. In the present work, we have developed an enzyme-linked immunosorbent assay (ELISA) based on the specificity of LPS for the detection of this pathogen. The ELISA specificity was confirmed after testing 36 biotype 2 strains from laboratory cultures and environmental samples, 31 clinical and environmental biotype 1 isolates, and several strains of Vibrio, Aeromonas, and Yersinia species, including the fish pathogens V. anguillarum, V. furnissii, A. hydrophila, and Y. ruckerii. The detection limits for biotype 2 cells were around 10(4) to 10(5) ce…

Quantifying transmission fitness costs of multi-drug resistant tuberculosis.

2021

As multi-drug resistant tuberculosis (MDR-TB) continues to spread, investigating the transmission potential of different drug-resistant strains becomes an ever more pressing topic in public health. While phylogenetic and transmission tree inferences provide valuable insight into possible transmission chains, phylodynamic inference combines evolutionary and epidemiological analyses to estimate the parameters of the underlying epidemiological processes, allowing us to describe the overall dynamics of disease spread in the population. In this study, we introduce an approach to Mycobacterium tuberculosis (M. tuberculosis) phylodynamic analysis employing an existing computationally efficient mod…

Saprophytism of a fish pathogen as a transmission strategy

2009

Fish farming creates conditions where disease transmission is enhanced and antibiotic treatments are commonly used to cure bacterial diseases to prevent severe losses due to infections. Ability to persist in such an environment has been suggested to lead to the evolution of high virulence. Columnaris disease caused by Flavobacterium columnare is a growing problem in freshwater fish farming. Transmission of the disease is poorly known, and survival of F. columnare in the rearing environment has not been studied. This paper addresses both transmission of columnaris disease and survival strategy of F. columnare. Saprophytic activity of F. columnare was studied by infecting rainbow trout finger…