The dengue virus consists of four antigenically related but distinct viruses, termed Dengue virus 1-4 (DEN 1-4). We have established that the dengue virus loses infectivity over time in solution in an exponentially declining manner. The four strains examined (one from each serotype) have half-lives that range from 2.5 to 7.5 hr in defined medium. The half-life is temperature and pH-dependent and is affected by the nature of the host cell in which it is produced, but is not dependent upon the presence of either Mg(2+) ions or chelating agents. Electron microscopy (EM) of solutions of the dengue virus show almost complete virus aggregation after 24 hr at room temperature, while RT-PCR shows an intact RNA genome. These results show that the solution environment of the dengue virus is an important determinant of dengue virus infectivity. 相似文献
Hypercytokinaemia is thought to contribute to highly pathogenic H5N1 influenza A virus disease. Glycyrrhizin is known to exert
immunomodulatory and anti-inflammatory effects and therefore a candidate drug for the control of H5N1-induced pro-inflammatory
gene expression. Here, the effects of an approved parenteral glycyrrhizin preparation were investigated on H5N1 virus replication,
H5N1-induced pro-inflammatory responses, and H5N1-induced apoptosis in human monocyte-derived macrophages. Glycyrrhizin 100 μg/ml,
a therapeutically achievable concentration, impaired H5N1-induced production of CXCL10, interleukin 6, and CCL5 and inhibited
H5N1-induced apoptosis but did not interfere with H5N1 replication. Global inhibition of immune responses may result in the
loss of control of virus replication by cytotoxic immune cells including natural killer cells and cytotoxic CD8+ T-lymphocytes. Notably, glycyrrhizin concentrations that inhibited H5N1-induced pro-inflammatory gene expression did not
affect cytolytic activity of natural killer cells. Since H5N1-induced hypercytokinaemia is considered to play an important
role within H5N1 pathogenesis, glycyrrhizin may complement the arsenal of potential drugs for the treatment of H5N1 disease. 相似文献
Influenza A virus infection of macrophages and virus-induced pro-inflammatory gene expression are regarded to contribute to
severity of influenza A virus-caused diseases. Although some data are available on cytokine production by influenza A virus-infected
macrophages, systematic comparisons of the virus types are currently considered to be of high relevance in humans (pandemic
H1N1/2009, seasonal H1N1, seasonal H3N2, highly pathogenic avian influenza H5N1) on pro-inflammatory potential, and relevant
underlying cellular signalling events are missing. Here, we show that the infection of human monocyte-derived macrophages
with pandemic H1N1/2009 (A/HH/01/2009), seasonal H1N1/1999 (A/New Caledonia/20/99), seasonal H3N2/2004 (A/California/7/2004)
or highly pathogenic H5N1/2004 (A/Thailand/1(Kan-1)/04) results in similar infection rates. However, the investigated H1N1
strains caused delayed and decreased apoptosis in comparison with H3N2/2004 or H5N1/2004. Moreover, human macrophage infection
with H3N2/2004 or H5N1/2004 but not with H1N1 viruses was associated with pronounced pro-inflammatory cytokine production
and activation of relevant mitogen-activated protein kinase pathways as indicated by phosphorylation of p38, JNK and ERK 1/2.
These findings are in line with clinical observations indicating enhanced disease severity in H3N2- or H5N1-infected patients
compared to individuals infected with pandemic H1N1/2009 or seasonal H1N1. 相似文献
Folic acid has been previously demonstrated to mediate intracellular nanoparticle uptake. Here, we investigated cellular uptake of folic acid-conjugated human serum albumin nanoparticles (HSA NPs). HSA NPs were prepared by desolvation and stabilised by chemical cross-linking with glutaraldehyde. Folic acid was covalently coupled to amino groups on the surface of HSA NPs by carbodiimide reaction. Preparation resulted in spherical HSA NPs with diameters of 239 ± 26 nm. As shown by size exclusion chromatography, 7.40 ± 0.90 μg folate was bound per mg HSA NPs. Cellular NP binding and uptake were studied in primary normal human foreskin fibroblasts (HFFs), the human neuroblastoma cell line UKF-NB-3, and the rat glioblastoma cell line 101/8 by fluorescence spectrophotometry, flow cytometry, and confocal laser scanning microscopy. Covalent conjugation of folic acid to HSA NPs increased NP uptake into cancer cells but not into HFFs. Free folic acid interfered with cancer cell uptake of folic acid-conjugated HSA NPs but not with uptake of folic acid-conjugated HSA NPs into HFFs. These data suggest that covalent linkage of folic acid can specifically increase cancer cell HSA NP uptake. 相似文献
We established a new highly sensitive method, PCR-ELISA, for the dectection of Babesia bovis in cattle for farms in Thailand. The detection of around 2.4 x 10(-8)% parasitemia (equivalent to 1 infected erythrocyte per 2 ml) was achieved by PCR amplification followed by the ELISA detection of a biotin tagged gene. When comparing the sensitivity of PCR-ELISA with the microscopic method, our PCR-ELISA method is more sensitive than thin blood smears by at least 1,000 times. The established PCR-ELISA also showed high specificity to B. bovis with no cross reaction to other endemic parasites except for A. marginale. Regarding the detection threshold for B. bovis, the PCR-ELISA method could detect parasites inoculated into splenectomized calves at least 1 week earlier than the thin blood microscopic method. The PCR-ELISA method is a valuable screening technique for B. bovis and applicable for the routine detection of carrier states and automated analysis. 相似文献