Biomedical subjects

V Hajnická

Publications and source records attributed to V Hajnická.

At least 19 recordsLinked to original sources

PubMed2005

Manipulation of host cytokine network by ticks: a potential gateway for pathogen transmission.

Ticks are obligatory blood-feeding arthropods that secrete various immunomodulatory molecules to antagonize host inflammatory and immune responses. Cytokines play an important role in regulating these responses. We investigated the extent to which ticks interact with the sophisticated cytokine network by comparing the effect of salivary gland extracts (SGE) of 3 ixodid tick species, Dermacentor reticulatus, Amblyomma variegatum and Ixodes ricinus, all of which are important vectors of tick-borne pathogens. Using specific ELISAs, anti-cytokine activity was demonstrated with 7 cytokines: IL-8, MCP-1, MIP-1alpha, RANTES, eotaxin, IL-2 and IL-4. The results varied between species, and between adult males and females of the same species. Relatively high activity levels were detected in saliva of female D. reticulatus, confirming that the observed anti-cytokine activities are an integral part of tick saliva secreted into the host. Results with fractionated SGE indicated that from 2 to 6 putative cytokine binding molecules are produced, depending on species and sex. Binding ability of SGE molecules was verified by cross-linking with radio-isotope labelled MIP-1alpha. By targeting different cytokines, ixodid ticks can manipulate the cytokine network, which will greatly facilitate blood-feeding and provide a gateway for tick-borne pathogens that helps explain why ticks are such efficient and effective disease vectors.

Animals↗

PubMed2002

Vesicular stomatitis virus nucleocapsid protein production in cells treated with selected fast protein liquid chromatography fractions of tick salivary gland extracts.

A salivary gland extract (SGE) prepared from 5-days-fed Dermacentor reticulatus female ticks was fractionated by fast protein liquid chromatography (FPLC). The effect of three FPLC fractions selected on the basis of anti-interleukin 8 (anti-IL-8) activity on vesicular stomatitis virus (VSV) nucleocapsid (N) protein formation in mouse L-cells was determined. Infected 14C-labeled cells treated with the FPLC fractions were analyzed by two-dimensional (2D) electrophoresis. The yields of VSV N protein were evaluated by Imagemaster software analysis. Most noticeable was an increase in the N protein production after treatment with the fraction 39 corresponding to the major peak of the anti-IL-8 activity. The nature of the substance in SGE that was responsible for this effect remains unclear.

Animals↗

PubMed2001

Effect of Mahonia aquifolium stem bark crude extract and one of its polysaccharide components on production of IL-8.

The crude hydroalcoholic extract of Mahonia aquifolium stem bark and a polysaccharide isolated from the extract were tested for their activity on interleukin-8 (IL-8) production by human monocytic cell line THP-1. The crude extract partly inhibited the IL-8 spontaneous production after 48-h treatment of the cells, while the polysaccharide was found to be a potent inducer of IL-8 production.

Berberidaceae↗

PubMed2001

Anti-interleukin-8 activity of tick salivary gland extracts.

Interleukin-8 (IL-8) is one of many mammalian chemokines (chemotactic cytokines) that direct mammalian inflammatory and immune cells to sites of injury and infection. Chemokines are produced locally and act on leucocytes through selective receptors. The principal role of IL-8 is to control the movement and activity of neutrophils. To date, several tick species have been shown to modulate the production or activity of certain cytokines but none of these are chemokines. Using an IL-8 specific ELISA, we showed that salivary gland extracts (SGE) from several ixodid tick species (Dermacentor reticulatus, Amblyomma variegatum, Rhipicephalus appendiculatus, Haemaphysalis inermis and Ixodes ricinus) reduced the level of detectable IL-8. Analyses of fractionated SGE revealed one similar peak of activity for D. reticulatus, A. variegatum and R. appendiculatus; a second peak, observed for D. reticulatus and A. variegatum, differed between the two species. Using radiolabelled IL-8, SGE and peak activity fractions of D. reticulatus were shown to bind the chemokine, and to inhibit binding of IL-8 to its receptors on human granuolocytes enriched for neutrophils. The biological significance of these observations was demonstrated by the ability of SGE to inhibit IL-8 induced chemotaxis of human blood granulocytes. Future isolation and characterization of the active molecules will enable determination of their functional roles in bloodfeeding and effect on tick-borne pathogen transmission.

Animals↗

PubMed2001

Significance of anti-interferon-alpha2 and sICAM-1 activities in the sera of viral hepatitis B and C patients treated with human recombinant interferon-alpha2.

In this study the presence of an IFN-binding activity in the sera of patients with chronic viral hepatitis B or C treated with rIFN-alpha2 was screened by a radioimmune assay (RIA) using radiolabeled rIFN-alpha2. Incidence of an anti-IFN activitywas compared with hepatitis B virus (HBV) or hepatitis C virus (HCV) serum markers as hepatitis B s antigen (HBsAg), hepatitis B e antigen (HBeAg), antibodies to HBsAg (anti-HBsAg), antibodies to HBeAg (anti-HBeAg), seroconversion, HBV DNA, HCV RNA, and serum soluble intracellular adhesion molecule I (sICAM). Injections (intramuscular) of rIFN-alpha2 caused an anti-rIFN activity formation in 8 (27.6%) of 29 patients with chronic active hepatitis B (CAH-B) and in 8 (30.8%) of 26 patients with chronic active hepatitis C (CAH-C). The presence of the anti-rIFN activity in CAH-B patients correlated frequently with the persistence of HBsAg, HBeAg and HBV-DNA, while its absence was often accompanied by the anti-HBeAg and anti-HBsAg seroconversion, respectively, and HBV-DNA negativity. In two CAH-C patients who became HCV RNA-negative no anti-IFN activity was found. Levels of serum sICAM-1 in CAH-B patients responding to the IFN treatment were higher than those in non-responders or in which the anti-IFN activity was present. The anti-IFN activity may negatively influence the effect of the IFN therapy of CAH-B or CAH-C patients at early stages of the therapy. The appearance of the anti-IFN activity at the end of a long-term IFN therapy does not seem to influence the outcome of the therapy. sICAM-1 may be involved in the process of CAH-B reactivation and IFN-triggered cytotoxicity during the IFN therapy.

Adult↗

PubMed2000

Inhibition of the antiviral action of interferon by tick salivary gland extract.

The saliva of haematophagous arthropods (e.g. mosquitoes, sandflies and ticks) contains potent immunomodulatory activities that counter their hosts' haemostatic, inflammatory and immune responses to facilitate blood-feeding. Such effects are exploited by arthropod-transmitted pathogens to promote their transmission. We investigated the ability of tick saliva to enhance arthropod-borne virus (arbovirus) transmission by determining its effect on the antiviral action of murine interferon (IFN alpha/beta). Salivary gland extract (SGE) was prepared from partially fed adult female Dermacentor reticulatus ticks that had been feeding on mice for either 3 or 5 days (SGED3 and SGED5, respectively). We demonstrated that SGE inhibits the antiviral effect of IFN as measured by a biological assay using vesicular stomatitis virus (VSV), and by two-dimensional electrophoretic analysis of the appearance of selected VSV proteins. The most pronounced effect was observed when mouse L cells were treated with SGE prior to IFN treatment. Following pretreatment with SGE, virus multiplication (which was fully blocked by IFN treatment alone) achieved yields similar to those obtained from infected cells not treated with IFN. Contemporaneous treatment, or treatment with SGE after IFN, was less effective. In parallel with these findings, formation of early viral proteins, N (nucleocapsid protein) and P (phosphoprotein), which was blocked by IFN, was detectable following pretreatment with SGE. The ability to inhibit the antiviral action of IFN was higher for SGED3 compared to SGED5. Demonstration that tick SGE can promote virus replication by suppressing the action of IFN helps explain why ticks are such efficient vectors of arboviruses.

Animals↗

PubMed2000

Comparison of the protein profiles of salivary gland extracts derived from three species of unfed and partially fed ixodid ticks analysed by SDS-PAGE.

Salivary gland extracts (SGE) from unfed and 5 days fed adult female Ixodes ricinus (Linnaeus, 1758); Haemaphysalis inermis (Birula, 1895) and Dermacentor reticulatus (Fabricius, 1794) ticks were prepared. The protein content after feeding increased by 10.6, 8.7 and 6.8 times, respectively. Extracts were equilibrated to the same protein content and submitted to SDS-polyacrylamide gel electrophoresis followed by computer analysis of the scanned gels. Relative differences in protein profiles of extracts obtained from unfed and partially fed ticks were found in all species and some of them were similar in all three species used in the study. Results demonstrate that the increase of the protein content in salivary glands during the feeding does not occur proportionally. Some proteins are synthesised preferentially (67.1 kDa, 13.5 kDa) but other bands (in range of 15-16 kDa) present in the SGE derived from unfed ticks are less discernible in that of fed ticks.

Animals↗

PubMed2000

Comparison of manganese superoxide dismutase precursor induction ability in human hepatoma cells with or without hepatitis B virus DNA insertion.

In a previous study (Hajnická et al., Acta virol. 38, 55-57 (1994)), we described synthesis of a 23 K protein in high amounts in the PLC/PRF/5 human hepatoma cell line after stimulation with sera of patients suffering from liver cirrhosis. In this study we identified this protein as manganense superoxide dismutase (Mn-SOD). When PLC/PRF/5 cells stimulated by various cytokines (interleukin-1 alpha (IL-1 alpha), IL-1 beta, tumor necrosis factor-alpha (TNF-alpha), TNF-beta, IL-6, tumor growth factor-alpha (TGF-alpha), TGF-beta, and interferon-gamma (IFN-gamma) were compared, the most effective was IL-1, followed by TNF-alpha and IL-6. Other cytokines had no effect on the stimulation of Mn-SOD. IL-1 alpha was selected for stimulation of Mn-SOD production in four human hepatoma cell lines (PLC/PRF/5, Hep-3B, Hep-G2 and Sk-Hep 1). Maximum Mn-SOD production occurred in PLC/PRF/5 cells. In other cell lines, Mn-SOD production was lower, reaching 35.7% and 31.5% in Hep-3B and Sk-Hep-1 cells, respectively, while it was only 4.3% in Hep-G2 cells.

Amino Acid Sequence↗

PubMed1999

Promotion of vesicular stomatitis virus nucleocapsid protein production by arthopod saliva.

In a previous study (Hajnicka, V. et al., Parasitology 116, 533-538, 1998), the infectivity titer of vesicular stomatitis virus (VSV) was shown to increase up to 10,000-fold when mouse L cells were treated with tick salivary gland extract (SGE) prior to infection. To examine this effect at the level of viral protein production, radiolabeled VSV-infected cells were analyzed by double-dimensional gel electrophoresis. A pre-treatment of cells with SGE from partially fed ticks in amounts corresponding to 1 or 3 salivary glands increased the level of both viral nucleocapsid (N) protein and phosphoprotein (P) in a dose-dependent manner. The effect was more pronounced for N protein and could account for the dramatic increase in infectious virus yield. Promotion of viral infectivity by arthropod saliva may support the arthropode-borne transmission cycle of VSV.

Animals↗

PubMed1998

Tick salivary gland extracts promote virus growth in vitro.

Saliva of blood-feeding arthropods promotes infection by the vector-borne pathogens they transmit. To investigate this phenomenon in vitro, cultures of mouse L cells were treated with a salivary gland extract (SGE) prepared from feeding ticks and then infected with vesicular stomatitis virus (VSV). At low input doses of VSV, viral yield was increased 100-fold to 10,000-fold by 16-23 h post-infection compared with untreated cultures, and depending on the SGE concentration. SGE-mediated acceleration of viral yield corresponded with the earlier appearance of VSV nucleocapsid protein as detected by 2-dimensional electrophoresis of infected cells. The observation that physiological doses of virus (i.e. doses likely to be inoculated by an infected arthropod vector into its vertebrate host during blood-feeding) respond to SGE treatment in vitro provides a new opportunity for identifying the factors in tick saliva that promote virus transmission in vivo.

Animals↗

PubMed1998

Therapy-induced antibodies to interferon-alpha 2a recognise its receptor-binding site.

Fifty-eight patients with chronic hepatitis B (HB) or C (HC) were treated with recombinant human interferon (rIFN)-alpha 2 and their sera were assayed for antibodies to rIFN-alpha 2c. Twelve of these patients produced low titres and two high titres of the antibodies. We localized the region which was recognised by the high-titre therapy-induced antibodies on the IFN molecule by testing the antibodies with a set of murine monoclonal antibodies (MoAbs) to IFN-alpha 2 in a competitive radioimmune assay (RIA). Only MoAbs with epitopes located in the amino-terminal portion of IFN-alpha 2 could inhibit the binding of radiolabelled IFN-alpha 2 by patients' sera. Our data indicate that the therapy-induced antibodies were directed to the receptor-binding domain of IFN-alpha 2 formed by amino acids (aa) 30-53. In accordance with this observation, human anti-IFN sera inhibited the binding of rIFN-alpha 2 to human cells.

Adult↗

PubMed1996

Interferon-omega suppresses hepatitis B surface antigen production in human hepatoma cell line.

Biological activities of human interferon (IFN) omega are less well characterized than those of other type I human IFNs. We compared the ability of recombinant IFN-omega, IFN-alpha 2 and IFN-gamma to inhibit the production of viral hepatitis B surface antigen (HBsAg) in the human hepatoma cell line PLC/PRF/5. The results demonstrated that the capacity of IFN-omega to suppress the HBsAg synthesis was similar to that of IFN-alpha 2. The kinetics of the inhibitory effect of IFN-gamma differed from those of the two other IFNs.

Antiviral Agents↗

PubMed1994

Effect of sera of cirrhotic patients with or without hepatitis B virus infection on protein synthesis in hepatoma cells.

The in vitro effects of sera of 11 patients with liver cirrhosis on protein synthesis in PLC/PRF/5 cells were studied. Hepatitis B virus (HBV) infection was documented in 7 patients. Increased random production of several cell proteins of M(r) of approximately 25, 65, 90 and 130 K was shown by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). There was no correlation between HBV-positive and HBV-negative cirrhosis and the induced proteins. One of them was identified as alpha-1 foetoprotein by immunoblot analysis. C-reactive protein (CRP) was determined only in one case; production of interleukin-6 (IL-6) was not detected.

Adolescent↗

PubMed1990

Relationship between depression of HBsAg production and DNA synthesis by interferons in human hepatoma cell line.

The influence of different interferons (IFNs) on HBsAg production and DNA synthesis was studied in PLC/PRF/5 cells using 30 I.U./ml of natural HuIFN-alpha, 25 I.U./ml of recombinant HuIFN-alpha 2, and 5 I.U./ml of natural murine IFN-alpha/beta. All three IFN types inhibited significant inhibitory effect on HBsAg production during the second 24 hr-interval following their addition. After 96 hr HBsAg production had returned to normal levels. Natural HuIFN-alpha clearly depressed cellular DNA synthesis 24 hr after IFN addition which returned to normal within the next 24 hr. Recombinant HuIFN-alpha 2 influenced DNA synthesis only slightly and the mouse IFN-alpha/beta showed no effect.

Carcinoma, Hepatocellular↗

PubMed1990

Transient increase of HBsAg levels following human IFN alpha treatment signalises the patient's response in chronic active hepatitis B.

Eleven patients in early stages of chronic active hepatitis B (CAH-B) were treated for weeks or months with a natural or recombinant human interferon alpha (Hu IFN alpha). Changes of serum levels of selected hepatitis B virus (HBV) markers were observed after Hu IFN alpha administration. Increase of HBsAg level accompanied by more or less simultaneous HBeAg level depression was the most interesting observation. These changes were well expressed in 5 reactive patients only; they usually ceased after withdrawal of IFN therapy. Reaction of the remaining 6 patients was either poor or not demonstrable. The possible mechanism for HBsAg/HBeAg serum level changes during the IFN therapy of CAH-B is discussed.

Acyclovir↗

PubMed1990

Immunological markers in patients with different forms of viral hepatitis B treated by "conventional" therapy or with HuIFN alpha.

Selected immunological, biochemical, and other viral hepatitis B (VH-B) markers were followed and analysed during "conventional" or human interferon alpha (HuIFN alpha) therapy of patients with different forms of VH-B. The immunological data obtained from "conventionally"-treated acute hepatitis B (AH-B), prolonged acute hepatitis B (AH-BP) or chronic active hepatitis B (CAH-B) patients disclosed differences unsatisfactory for comparison of the influence of HuIFN alpha therapy on changes of the immunological markers. More valuable data were obtained through continuous registration of the dynamics of selected blood markers. Partial effects on immunological parameters were seen after HuIFN alpha administration to 2 patients with developing CAH-B infection. Progression of the disease was markedly halted in these both patients after IFN treatment.

Acute Disease↗

PubMed1987

Dynamics of serum markers in the different course of hepatitis B virus (HBV) infection.

The presence of serum markers of hepatitis B virus (HBV) infection in different stage of illness has a specific pathogenic and diagnostic significance. Based on the frequency of the appearance of HBV markers in patients' sera at different stages of the illness, we attempted a grouping possibly helpful for differentiation, epidemiologic and prognostic evaluation of hepatitis. The significance for chronic disease development of the dynamics of HBV marker levels in the serum is discussed.

Acute Disease↗

PubMed1987

Effect of human leukocyte interferon on HBsAg production in PLC/PRF/5 human hepatoma cell line.

We describe the effect of the natural human interferon alfa (HuIFN alfa) on HBsAg production in PLC/PRF/5 cells. Decreased HBsAg production was regularly demonstrated 48 hr after the treatment of cells with 3-300 IU of HuIFN alfa/ml; it lasted for further 24-48 hr depending from the amount of interferon (IFN) added. We found no differences in the sensitivity to HuIFN alfa of non-confluent cells as compared to cells which had reached confluency. The decrease of the extracellular HBsAg excretion seems to be due to inhibition of intracellular HBsAg formation.

Antiviral Agents↗