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At least 145 records · Page 8Linked to original sources
PubMed2001

[Diagnostic pitfalls in infectious disease pathology].

Numerous images observed in histopathology and cytopathology can mimic pathogens such as mycotic agents, parasites (protozoa or helminthes), bacteria or virus. An error of diagnosis may provoke the administration of a non efficient treatment which can also be toxic. The present review describes these false pathogens which can correspond to exogenous or endogenous agents. Basic morphological analysis of mycotic agents, parasites, bacteria and cytopathogenic viral effects are successively presented. Then, the main diagnostic pitfalls which can be observed during these infections are exposed. Finally, diagnostic problems occurring in case of contamination are rapidly cited.

Bacterial Infections↗
PubMed2002

Evaluation of the innate immune response in pups during canine parvovirus type 1 infection.

In two pups (A and B) naturally infected with canine parvovirus type 1 (CPV1) phagocytic responses were evaluated over a period of two weeks (day 0 = T0; day 3 = T1; day 7 = T2; day 14 = T3). CPV1 infection led to a marked reduction of monocyte (MO) phagocytosis in both pups. Also MO killing was impaired and in pup B this function was totally absent. Polymorphonuclear (PMN) phagocytosis values of both pups fluctuated within normal ranges, as well as PMN killing of pup A. In pup B, killing exerted by PMN was absent at T0, then increased but again dropped below normal ranges at T3. The described alterations of phagocytic functions may be regarded as possible viral mechanisms of immune evasion.

Animals↗
PubMedDate not supplied

[Ebola virus reproduction in cell cultures].

Ebola-Zaire virus production in Vero and BGM cells was studied. The CPE developed in both cell cultures. The cell monolayer destruction by 80-90% was seen at a low multiplicity of infection in 7-8 days after virus inoculation. An overlay composition was developed for virus titration using plaque assay. The plaque production was shown to be directly proportional to the virus dose. The curve of Ebola virus production in Vero cell culture fluid was determined. At a multiplicity of infection of 0.01 PFU/cell, the maximum virus titer of 10(6.4) PFU/ml was reached in 7 days postinfection. Specific antisera were generated by inoculation of guinea pigs. Indirect immunofluorescent assay was used for testing of virus-specific antigen and antibody.

Animals↗
PubMed1975

Spontaneous lymphoma associated with Herpesvirus saimiri in owl monkeys.

Two cases of lymphoma and one case of lymphoproliferative disease were found in a group of 7 owl monkeys imported into our colony as a single group. Herpesvirus saimiri (HVS) was isolated from the tumor cells of 1 lymphoma by cocultivation and from kidney cell cultures from the monkey with lymphoproliferative disease. Antibody to HVS was found in serum samples from 2 monkeys positive for HVS but not in the sera from the 4 clinically normal monkeys. Antibody to Epstein-Barr virus-infected cells was also found in the serum from the animal with lymphoma.

Animals↗
PubMed2005

Antiviral activity of oligomerization-deficient Stat1.

Interferon stimulation of cells can activate several hundred target genes, many of which are required for antiviral protection. Promoter binding of tyrosine-phosphorylated (activated) Stat1 dimers is essential for gene induction, a process that often entails the oligomerization of Stat1 dimers via interactions of their aminoterminal domains. The mutation of a single residue (F77) in the N-domain of Stat1 was recently demonstrated to preclude both the dephosphorylation and the oligomerization of Stat1 dimers. Here, we investigated the influence of defective oligomerization on a complex phenotype such as the induction of an antiviral state. It was found that the antiviral protection conferred by interferon-a was strongly reduced, whereas the interferon-g response was not measurably affected. These results indicate that Stat1 oligomerization is required for the antiviral activity of interferons. Moreover, the concentration of activated Stat1 in the nucleus may generally play a critical role for interferon-induced target gene activation.

Antiviral Agents↗
PubMed1991

Demonstration of virus-specific cytotoxic T lymphocytes in liver tissue in hepatitis A--a model for immunopathological reactions.

The pathogenetic mechanism leading to liver tissue injury in hepatitis caused by hepatitis A virus is unclear. We have randomly established T cell clones from liver biopsies from 4 patients with hepatitis A. A total of 578 clones was phenotypically analyzed. Whereas during the acute phase of disease CD8+ clones dominated over CD4+ clones, from a biopsy taken late after onset of clinical syndromes more CD4+ than CD8+ clones were obtained. Interestingly, in a patient with a second exacerbation of the disease, more than 20% of all clones had the CD3+ WT31- CD4- CD8- gamma delta TCR+ phenotype. Variable IFN-gamma production was observed with all types of T cell clones. All CD8+ clones had cytotoxic activity, and approximately 60% of all CD8+ clones showed specific cytotoxicity against autologous fibroblasts infected with hepatitis A virus but not with herpes simplex, adeno- or enteroviruses. These results show that the liver injury in hepatitis A is not caused by a viral cytopathogenic effect but is due to an immunopathological reaction of sensitized cytotoxic T lymphocytes against infected hepatocytes. In addition, these studies show an enrichment of CD4-8- alpha beta T cell receptor negative T lymphocytes at the site of an inflammation and suggest a role of these cells in an antiviral reaction.

Antigens, CD↗
PubMed1990

NMR investigation of cell cultures: early detection of infection by Herpes simplex virus type 2 and transformation.

The water proton Nuclear Magnetic Resonance (NMR) spin-lattice relaxation rates were measured in suspension of uninfected and Herpes simplex virus type 2-infected WI-38 diploid cells and shown to allow reliable detection of (i) the early signs of productive infection, and (ii) the tendency to undergo either spontaneous or virus-induced transformation. In addition, NMR investigation of several transformed cell lines currently and previously established from WI-38 cells clearly indicated that the NMR relaxation parameter is a suitable tool for assessment of the level of malignancy, as revealed by in vivo oncogenicity tests in immunosuppressed mice.

Animals↗
PubMedDate not supplied

Some results obtained in the "Stefan S. Nicolau" Institute of Virology by the study of herpes simplex virus.

The results obtained in the "Stefan S. Nicolau" Institute of Virology by the study of herpes simplex virus (HSV) are reviewed. The investigations were mainly focused on HSV biology, genetic markers, experimental HSV infection, correlation between HSV and some diseases, action of some chemical and biological preparations on HSV, in vitro and in vivo HSV oncogenicity, HSV-induced surface antigens, a.o.

Animals↗
PubMed1987

[Release of polyoma virus from transformed human cells].

Virus reproduction and activation were studied in human cells transformed with human polyoma virus. At the stage of spontaneous viral production, such methods of activation as somatic hybridization and DNA transfection were successful. Special methods of viral activation (treatment with mitomycin C and DEAE--dextran, and subsequent homologous DNA transfection) were required when viral production by cells ceased completely.

Cell Line↗
PubMed1985

Polykaryocytosis induced by amphotropic murine C-type virus (AP129) in Sac-cells nonproductively transformed by Moloney murine sarcoma virus (MO-MSV).

Nonproducer cells of STU mouse origin (Sac) transformed with Moloney murine sarcoma virus (Mo-MSV) and superinfected with the amphotropic murine C-type virus strain AP 129 unexpectedly formed polykaryocytes. The multinuclear giant cells appeared about 30 days after AP 129 infection as confirmed in three independently performed experiments. The majority of the Sac-cells became involved in syncytium formation. The polykaryocytes disappeared during continued culture transfers. Various cell lines obtained by limiting dilution showed the same reactivity as the parental cell line. Release of sarcoma-helper virus complex was observed before and during the appearance of the polykaryocytes as well as after their disappearance at about day 50 after infection. In normal STU mouse embryo fibroblasts, normal Balb/3T3 cells or another Mo-MSV transformed nonproducer cells (MSV85 C13; Balb origin) infected with AP 129 no polykaryocytes developed. The sarcoma-helper virus complex released from AP 129 infected Sac-cells led to transformation of cultured cells from different mammalian species (mink, goat, dog). However, when observed for at least 30 days these cultures did not show polykaryocyte formation.

Animals↗
PubMed1987

Potiskum virus: enhancement of replication in a macrophage-like cell line.

Replication of Potiskum virus was studied in P388D1 macrophage-like cell line in the presence and absence of subneutralizing concentrations of specific antiviral antibody. The cultures were infected at multiplicities of infection (MOI) ranging from 0.4 to 0.0004. The virus replicated to high titres at all MOI tested, but there was an enhancement of virus replication in cultures supplemented with the antibody. Enhancement of replication was MOI dependent, the highest ratios being obtained in cultures infected at lowest MOI. In enhancement assays using various dilutions of immune mouse ascitic fluid (IMAF), the highest enhancement ratio was observed at dilution 1 : 500; the enhancing antibody titre was 5,000.

Animals↗