Ebola and Marburg haemorrhagic fever.

Ebolaviruses and Marburgviruses (family Filoviridae) are among the most virulent pathogens for humans and great apes causing severe haemorrhagic fever and death within a matter of days. This group of viruses is characterized by a linear, non-segmented, single-stranded RNA genome of negative polarity. The overall burden of filovirus infections is minimal and negligible compared to the devastation caused by malnutrition and other infectious diseases prevalent in Africa such as malaria, dengue or tuberculosis. In this paper, we review the knowledge gained on the eco/epidemiology, the pathogenesis and the disease control measures for Marburg and Ebola viruses developed over the last 15 years. The overall progress is promising given the little attention that these pathogen have achieved in the past; however, more is to come over the next decade given the more recent interest in these pathogens as potential public and animal health concerns. Licensing of therapeutic and prophylactic options may be achievable over the next 5-10 years.

Type 1 wild poliovirus and putative enterovirus 109 in an outbreak of acute flaccid paralysis in Congo, October-November 2010.

An outbreak of flaccid paralysis syndrome in adults is ongoing in Congo. Molecular analysis of faecal, throat and cerebrospinal samples identified wildtype 1 poliovirus and an additional enterovirus C strain related to enterovirus 109 as the cause. As of 22 November, the cumulative number of cases was 409, of which 169 (41.3%) were fatal. This is one of the largest wild type 1 poliovirus outbreaks ever described associated with an unusually high case fatality rate.

A real-time RT-PCR method for the universal detection and identification of flaviviruses.

Here we describe an optimized molecular protocol for the universal detection and identification of flaviviruses. It combines the convenient real-time polymerase chain reaction (PCR) format with a broad spectrum of flavivirus detection. This assay, based on the amplification of a 269-272 nt (depending on the flavivirus tested) region at the N terminal end of the NS5 gene, enabled the amplification of 51 flavivirus species and 3 tentative species. Sequencing of the amplicons produced by reverse transcriptase (RT)-PCR permitted the reliable taxonomic identification of flavivirus species by comparison with reference sequences available in databases, using either the BLASTN algorithm or a simple phylogenetic reconstruction. The limit of detection of the assay (2-20,500 copies/reaction depending on the virus tested) allowed the detection of different flaviviruses from a series of human sera or veterinary samples. Altogether, the characteristics of this technique make it a good candidate for the identification of previously identified flaviviruses in cell culture and the investigation of field samples, and also a promising tool for the discovery and identification of new species, including viruses distantly related to "classical" arthropod-borne flaviviruses.

Specific expression of matrix metalloproteinases 1, 3, 9 and 13 associated with invasiveness of breast cancer cells in vitro.

Several matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were studied in highly invasive (MDA-MB-231) and slightly invasive (MCF-7, T47D, BT-20) breast cancer cell lines. Investigations were carried out at the protein level and/or at the mRNA level, either in cells cultured as monolayers on plastic, or in cells seeded on a thin layer of Matrigel basement membrane matrix. Analysis of MMP expression by RT-PCR showed expression of MMP-1. MMP-3, and MMP-13 in highly invasive MDA-MB-231 cells, but not in slightly invasive cell lines. The extracellular secretion of MMP-1 and MMP-3 by MDA-MB 231 cells could be also shown by ELISA. TIMP-1 and TIMP-2 mRNAs were found in all cell lines, however, the extracellular secretion of both TIMPs was much higher in MDA-MB-231 cells than in the other cell lines. When the cells were cultured on Matrigel matrix, MMP-9 expression was induced in MDA-MB-231 cells only, as assessed by RT-PCR and zymography experiments. The invasive potential of MDA-MB-231 cells evaluated in vitro through Matrigel was significantly inhibited by the MMP inhibitor BB-2516, by 25% and 50% at the concentrations of 2 x 10(-6) M and 10(-5) M, respectively. In conclusion, our data show that highly invasive MDA-MB-231 cells but not slightly invasive T47D, MCF-7 and BT-20 cells express MMP-1, MMP-3, MMP-9 and MMP-13. MMP-9 which is specifically up-regulated by cell contact to Matrigel, may play a key role in the invasiveness of MDA-MB-231 cells through basement membranes.

Selective induction of the secretion of cathepsins B and L by cytokines in synovial fibroblast-like cells.

We have investigated the potent influence of some cytokines, tumour necrosis factor-alpha (TNF-alpha), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and interferon-gamma (IFN-gamma), on the secretion of cysteine proteinases (cathepsins B and L) by cultured synovial fibroblast-like cells from patients with rheumatoid arthritis (RA). After treatment of synovial fibroblast-like cells with cytokines, culture media were evaluated for cathepsins B and L by enzyme immunoassays, and for cathepsin B and L activities using the enzymatic substrates. Z-Phe-Arg-AMC and Z-Arg-Arg-AMC, and specific inhibitors. Treatment of synovial fibroblast-like cells with TNF-alpha or PDGF resulted in a marked increase in cathepsin B secretion. Moreover, after prolonged PDGF treatment, the amount of secreted cathepsin B returned to the low control level. In contrast, bFGF led to increased cathepsin L secretion. IFN-gamma induced both cathepsin B and L secretion. Our results show that cytokines induce a selective secretion of cathepsins B and L by synovial fibroblast-like cells. This selective effect of cytokines on the secretion of cysteine proteinases suggests that synovial fibroblast-like cell-mediated articular degradation is a highly regulated process.

Regulation of cathepsin D dependent on the phenotype of colon carcinoma cells.

We have studied the intracellular trafficking of cathepsin D in different colon carcinoma cell populations: the HT-29 cell line, composed of >95% undifferentiated cells; 2 subpopulations derived from this cell line, containing cells committed to differentiation into mucin-secreting cells (HT-29 MTX) or enterocyte-like cells (HT-29 G-) after confluence; and the Caco-2 cell line, which spontaneously differentiates into enterocyte-like cells after confluence. Post-confluent undifferentiated HT-29 cells and differentiated enterocyte-like HT-29 G- and Caco-2 cells secrete significant levels of cathepsin D in culture medium, in contrast to post-confluent differentiated mucin-secreting HT-29 MTX cells, which secrete this enzyme at a very low level. The intracellular content and the mRNA level of cathepsin D increase after confluence in the different cell types, particularly in Caco-2 cells, which intensify the secretion of cathepsin D along with the differentiation process post-confluence. Membrane-associated mature cathepsin D was detected in HT-29 cells but not in Caco-2 cells. In the different types of cell, pro-cathepsin D associates with the membrane concomitantly to its binding to an Mr 72,000 protein. Membrane association persists after dissociation of the complex in HT-29 cells but not in Caco-2 cells. In the mucin-secreting HT-29 MTX cells, cathepsin D was immunolocalised to the membrane of mucin vacuoles localised under the brush border. Our results show that cathepsin D can be regulated differently in colon carcinoma cells, and this finding might have specific functional implications for each cell type.

The state of differentiation of HT-29 colon carcinoma cells alters the secretion of cathepsin D and of plasminogen activator.

We have studied the cellular content and the extracellular release of cathepsins B and D, and of plasminogen activator, in 2 different tumor cell populations before confluence and after late confluence: the HT-29 colon carcinoma cell line, which contains primarily undifferentiated cells, and a subpopulation derived from this cell line, which contains cells committed to differentiation into mucus-secreting goblet cells after confluence. In both populations, cellular cathepsin-B activity increased after confluence, and latent cathepsin B was found in all culture media. In the parental cell line, cellular cathepsin D activity decreased after confluence; however, cathepsin D was secreted at high levels into the extracellular medium. In contrast, in the subpopulation of cells committed to differentiation, cellular cathepsin D activity increased after confluence, and cathepsin D was not secreted into the extracellular medium, but was immunolocalized in the apical brush border of the differentiated cells. Plasminogen activator of urokinase type was identified by immunocytochemistry. Both subconfluent cell populations, and the post-confluent undifferentiated cell population, produced plasminogen activator activity at similar levels. In contrast, in the differentiated postconfluent cells, the production of plasminogen activator activity was markedly lower. Our data show that the differentiation of HT-29 colon carcinoma cells into mucus-secreting cells impairs the secretion of plasminogen activator and cathepsin D, but does not affect cathepsin B.

Heterozygous hypobetalipoproteinemia with fasting chylomicronemia.

We describe a disorder in which low-density lipoprotein (LDL)-cholesterol and apolipoprotein B are in low concentration (0.47 mmol/L and 0.28 g/L, respectively) and chylomicrons are still present in plasma after an 18-h fast. The d less than 1.006 fraction was isolated by flotation ultracentrifugation and the apolipoproteins were analyzed by electrophoresis, immunoblotting with anti-apolipoprotein B-100 antiserum, and isoelectric focusing. In the d less than 1.006 fraction of the fasting serum, we found an apolipoprotein B form with the same apparent molecular mass as apolipoprotein B-48 and similar in amount to apolipoprotein B-100 (respective percentages, 46% and 54%). The monosialylated form of the apolipoprotein C-III was severely decreased. After an oral fat load, the repartition of the two species of apolipoprotein B did not change greatly (respective percentages, 60% and 40%), and the concentration of serum triglyceride increased only from 1.20 to 1.65 mmol/L.

Serum lipid and lipoprotein abnormalities in human African trypanosomiasis.

We have studied the serum lipoprotein system in human African trypanosomiasis (Trypanosoma brucei gambiense infection). The study was carried out on 74 Congolense patients suffering from sleeping sickness and 34 Congolense control subjects living in the endemic region of Boko Songho. We have determined the serum concentrations of lipids (triglycerides, cholesterol, phospholipids) and apolipoproteins (apolipoprotein A-I and B), and the separation of serum lipoproteins by electrophoresis. For the patients infected with T. b. gambiense, in comparison with control subjects, the results have shown (i) a significant increase in triglyceride concentration and a decrease in cholesterol concentration; (ii) a significant rise in apolipoprotein B concentration and a significant reduction in apolipoprotein A-I concentration; and (iii) an increase in low density lipoproteins and a decrease in high density lipoproteins. We conclude, therefore, that human African trypanosomiasis is associated with marked alterations in the composition and levels of host lipoproteins.