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Biomedical subjects

M Divizia

Publications and source records attributed to M Divizia.

At least 37 records · Page 2Linked to original sources
PubMed1993

Mutations in the 3A genomic region of two cytopathic strains of hepatitis A virus isolated in Italy.

Two strains of hepatitis A virus (HAV) were isolated in cell culture and found to induce a cytopathic effect at early passages. The nucleotide sequences of the 5' non-translated region (5'NTR) and of genes 2B, 2C, 3A and 3B were determined for these strains and found to contain mutations similar to those detected in cell-culture adapted variants of HAV strain HM175. In addition, gene 3A shows a deletion of three aspartic acid residues near the N-terminus of the polypeptide. In combination with variations in the 5'NTR and in genes 2B and 2C, the absence of an aspartic acid residue in position 4 of gene 3A of three cytopathic clones of HM175 suggests a possible role of the 3A protein in determining the cytopathic phenotype.

Aspartic Acid↗
PubMed1992

Methisoprinol-effect on the replication cycle of human hepatitis A virus.

The antiviral activity of methisoprinol was investigated under different conditions using a strain of hepatitis A virus (HAV), that shows a strong cytopathic effect on the Frp/3 cell line 7-9 days post-infection. Treatment of Frp/3 at a dose range of 125-1200 micrograms/ml had no toxic effect and showed a dose dependent inhibition of the HAV replication cycle. At the methisoprinol dose of 500 micrograms/ml the cytopathic effect was completely abolished and HAV antigen production reduced by 50% as measured by indirect immunofluorescence (IIF) and commercial enzyme-linked assay (ELISA). The virus yield was virtually abolished at the highest dose employed (1000 micrograms/ml).

Animals↗
PubMed1991

Influence of polyions on the early steps of enterovirus infection.

The influence of electric charged molecules on the early phases of enterovirus infection was studied in order to select antiviral compounds able to prevent viral attachment. The effect of different polyelectrolytes on the multiplication of coxsackie virus B3, echovirus 6 and hepatitis A virus was investigated in susceptible cells by adding the drug before, during or after the viral adsorption period. Among polyanions, the polysaccharides heparin and dextran sulfate inhibited viral infectivity, dextran sulfate being the most effective mainly towards hepatitis A virus infection. DEAE-dextran and protamine sulfate, generally recognized as enhancers of infectivity of naked and enveloped viruses, exhibited an inhibitory effect towards the three picornaviruses tested. Only in the case of hepatitis A did DEAE-dextran slightly improve viral antigen synthesis. The inhibitory effect shown by compounds belonging to positive and negative polyions suggests that the electric charge is not sufficient by itself to explain the antiviral activity of these drugs.

Animals↗
PubMed1990

An outbreak of hepatitis A in young adults in central Italy.

Between September, 1988 and January, 1989 a common source outbreak of 47 cases of serologically confirmed hepatitis A occurred in a town of central Italy. Thirty-eight cases were primary, three co-primary and six secondary. The highest age-specific attack rate was seen in subjects aged 15-24 years (120 per 100,000); the mean age of cases was 24.6 years and the median age was 22 years. A matched triplet case-control study showed significant association between the disease and consumption of either raw mussels (41% of cases, compared with 10% of controls; P less than 0.0001) or a single brand of mineral water (63% of cases, compared with 41% of controls; P less than 0.05). The mean age of the cases reflects the shift in primary susceptibility to the infection from younger to older age groups, a finding which has recently been demonstrated by several seroepidemiological surveys in Italy.

Adolescent↗
PubMed1990

Characterization by T1-oligonucleotide fingerprinting of three strains of human hepatitis A virus isolated in Italy.

Three human hepatitis A virus strains, all of them isolated in Italy but one acquired abroad, were analyzed by T1-RNAase oligonucleotide mapping and by monoclonal antibody neutralization. The variation among their genomes according to T1-maps was calculated to be about 9%, thus confirming the poor genomic variation assessed by nucleotide sequencing (1-10%). However T1-maps of these Italian isolates were different from those reported in the literature (Weitz and Siegl, 1985). Neutralization by monoclonal antibody caused a reduction in titres of 2-25 log10. This genomic stability, if confirmed, is important with a view to a valuable vaccine.

Adult↗
PubMed1990

Effect of inhibitors of cytoplasmic structures and functions on rabies virus infection in vitro.

The effect in vitro of some cytoplasmic structure and function inhibitors on the different stages of rabies virus infection was investigated. Treatment of fibroblasts (CER) and human neuroblastoma cells (IMR-32) with substances acting on low pH intracellular compartments (methylamine and monensin) prevented rabies virus genome delivery in the cytosol. An early inhibition of viral infection was also obtained in the presence of B and D cytochalasins and trifluoperazine which interact with microfilament structures. Treatment with colchicine and vinblastine did not affect rabies multiplication, suggesting that microtubules are not involved in this process. However, the multiplication of prebound virions did not take place in the presence of inhibitors of oxidative phosphorylation (sodium azide and CCCP) and of glycolysis (2-deoxy-D-glucose) indicating that rabies virus replication is largely energy-dependent in both host cells examined.

Animals↗
PubMed1990

Susceptibility of mammalian, avian, fish, and mosquito cell lines to rabies virus infection.

The relationship between plasma membrane receptor organization and cell susceptibility in vitro was investigated in mammalian, avian, fish, and arthropod cell lines infected with fixed rabies virus. IMR32, HeLa, CER, and EPC cells were widely susceptible to infection with CVS virus, whereas a lower level of specific viral antigens was detectable in A. albopictus cells. In spite of these differences, the amount of infectious virus particles bound to the various cell surfaces was similar. Competition experiments carried out with plasma membranes extracted from ability of these components to bind the virus and to prevent infection. The different cellular permissiveness to rabies infection described here did not correlate with significant differences in number or in chemical structure of the receptor binding sites, but more likely with events following virus adsorption.

Adsorption↗
PubMed1989

Effect of cellular function inhibitors on the infection of Frp/3 cells by hepatitis A virus.

The effect of some cellular function inhibitors on hepatitis A virus (HAV) adsorption and on the successive events of infection in a monkey cell line (Frp/3 cells) was investigated. Treatments of Frp/3 cells with colcemide, vinblastine and cytochalasin D, which affect cytoskeleton organization, indicated that neither microtubules nor microfilaments play an important role in the early events of HAV infection. Monensin, which acts as an ionophore on intracellular vesicle compartments inhibited HAV infection probably at the uncoating step. Inhibition of viral replication to a different degree was observed with both inhibitors of oxidative phosphorylation, such as dinitrophenol and sodium azide, and with an inhibitor of glycolysis, 2-deoxy-D-glucose. However, none of these compounds significantly affected the early steps of infection, thus demonstrating that HAV replication is largely dependent upon cell energy.

Azides↗
PubMed1989

Morphological changes in HAV-infected Frp/3 cells and immunolocalization of HAAg.

Electron and immunoelectron microscopic studies were carried out on HAV-infected Frp/3 cells. The infection led to a distinctive cytopathic effect (CPE) arising on day 3 up to the complete detachment of monolayers on day 7. Infected cells exhibited progressive modifications, beginning from the formation of long helical polyribosomes. Subsequently, hypertrophy, cisternal dilatation and degranulation of the RER could be observed. Furthermore, the formation of concentric membranous bodies (CMB), large myelin-like structures and annulate lamellae could be revealed at later times of infection. 24-27 nm virus-like particles were observed within cytoplasmic vesicles or outside extensively degenerated cells. Indirect immunoperoxidase staining were used to localize HAV antigen (HAAg) in thin sectioned infected Frp/3 cells. Vesicular inclusion bodies, often seen to contain electron-lucent particles, resulted darkly stained as well as tracts of the RER and myelin-like structures. Negatively stained preparations from cell lysates revealed small clusters of HAV particles which sometimes appeared to be still associated with residual membrane fragments. Our findings seem to suggest that HAV replication occurs in close association with cytoplasmic membranes and a direct involvement of the RER seems to be demonstrated.

Antigens, Viral↗
PubMed1989

Ultrafiltration: an efficient second step for hepatitis A virus and poliovirus concentration.

The efficiency of seeded hepatitis A virus and poliovirus recovery from 1 l of dechlorinated tap water or different buffer was evaluated using a molecular filtration system. All the experiments were performed using a polysulfonate membrane of 10,000 molecular weight limit. Under standard conditions hepatitis A virus recovery was 100% of the input, but the percentage was reduced dramatically when the inflow pressure was increased. In contrast, poliovirus recovery was low under standard conditions, but it improved when the membranes were pretreated with different buffers. The best recovery was obtained using beef extract at neutral pH.

Buffers↗
PubMed1989

Membrane lipid components interacting with hepatitis A virus.

The involvement of lipid components in hepatitis A virus (HAV) attachment to host cells has been investigated. Isolated Frp/3 cell membranes and whole lipids, phospholipid and glycolipid fractions extracted from them were able to bind the virus and to prevent infection. Treatment of virus with various phospholipids or glycolipids demonstrated the participation of phosphatidylserine, phosphatidylethanolamine and galactose in HAV binding. Results obtained added further information on the receptor specificity of host cells for HAV.

Animals↗
PubMed1987

Study of the chemical nature of Frp/3 cell recognition units for hepatitis A virus.

Research has been carried out in order to clarify the chemical nature of cell receptors interacting with a fast growing strain of hepatitis A virus (HAV) producing a cytopathic effect on Frp/3 cells. Cell surface susceptibility to HAV attachment has been studied after treatment with enzymes acting on different chemical groupings. Results obtained showed a lowering of cell susceptibility to HAV infection following the action of phospholipase A2, phospholipase C, trypsin and beta-galactosidase. These data suggested that phospholipids, proteins and galactose participate to the cellular receptorial area for HAV.

Cell Line↗
PubMed1987

Detection of hepatitis A virus in the stools of healthy people from endemic areas.

One-hundred-ninety-two stool samples were tested for the presence of human Hepatitis A antigen. Sixteen of these were also evaluated for the presence of infectious virus. All samples were obtained from young and apparently healthy people from endemic areas for Hepatitis A disease. The isolation of the infectious virus from these stools demonstrates clearly the wide diffusion of the virus in these areas, and its transmission by the oral-fecal route.

Adolescent↗
PubMed1987

The effect of lipophilic amines on the growth of hepatitis A virus in Frp/3 cells.

The effect of lipophilic amines on hepatitis A virus infection in a monkey cell line (Frp/3 cells) was studied. Ammonium chloride, amantadine, methylamine and dansylcadaverine inhibited viral antigen synthesis when added to the cells at least one hour after the attachment step. Results obtained suggest that the HAV entry pathway in Frp/3 cells follows an endocytic route and that viral uncoating takes probably place in endosomes and/or lysosomes.

Amantadine↗
PubMed1986

Preliminary characterization of a fast-growing strain of human hepatitis A virus.

A fast-growing strain of Human Hepatitis A (HHA) virus was selected by progressively shortening by the time between serial passages of the isolate in the simian cell line Frp/3. The virus so selected infected 90-95% of the cells in 7-10 days, and developed a strong cytopathic effect (CPE). The synthesis of HHA-specific antigens and the CPE were neutralized simultaneously by standard anti-HHA sera. This fast-growing strain has the characteristics of a picornavirus.

Animals↗
PubMed1986

Comparison of indirect immunofluorescence and radioimmunoassay for detecting antibodies against hepatitis A virus of the IgG and IgM classes.

Indirect Immunofluorescence test (IIF) and Radioimmunoassay (RIA) were compared for determining anti-Hepatitis A virus (HAV) IgG and IgM. 142 sera were tested for anti-HAV IgG and 16 for anti-HAV IgM, both with IIF and RIA techniques. The correlation between the results reached 98.6% for anti-HAV IgG and 93.75% for anti-HAV IgM detection, confirming the specificity and sensibility of IIF.

Adult↗