Ebola Virion Attachment and Entry into Human Macrophages Profoundly Effects Early Cellular Gene Expression

Zaire ebolavirus (ZEBOV) infections are associated with high lethality in primates. ZEBOV primarily targets mononuclear phagocytes, which are activated upon infection and secrete mediators believed to trigger initial stages of pathogenesis. The characterization of the responses of target cells to ZEBOV infection may therefore not only further understanding of pathogenesis but also suggest possible points of therapeutic intervention. Gene expression profiles of primary human macrophages exposed to ZEBOV were determined using DNA microarrays and quantitative PCR to gain insight into the cellular response immediately after cell entry. Significant changes in mRNA concentrations encoding for 88 cellular proteins were observed. Most of these proteins have not yet been implicated in ZEBOV infection. Some, however, are inflammatory mediators known to be elevated during the acute phase of disease in the blood of ZEBOV-infected humans. Interestingly, the cellular response occurred within the first hour of Ebola virion exposure, i.e. prior to virus gene expression. This observation supports the hypothesis that virion binding or entry mediated by the spike glycoprotein (GP1,2) is the primary stimulus for an initial response. Indeed, ZEBOV virions, LPS, and virus-like particles consisting of only the ZEBOV matrix protein VP40 and GP1,2 (VLPVP40-GP) triggered comparable responses in macrophages, including pro-inflammatory and pro-apoptotic signals. In contrast, VLPVP40 (particles lacking GP1,2) caused an aberrant response. This suggests that GP1,2 binding to macrophages plays an important role in the immediate cellular response

Human Fatal Zaire Ebola Virus Infection Is Associated with an Aberrant Innate Immunity and with Massive Lymphocyte Apoptosis

Ebolavirus, especially the species Zaïre (ZEBOV), causes a fulminating hemorrhagic fever syndrome resulting in the death of most patients within a few days. In vitro studies and animal models have brought some insight as to the immune responses to ZEBOV infection. However, human immune responses have as yet been poorly investigated, mainly due to the fact that most outbreaks occur in remote areas of central Africa. Published studies, based on small numbers of biological samples have given conflicting results. We studied a unique collection of 50 blood samples obtained during five outbreaks that occurred between 1996 and 2003 in Gabon and Republic of Congo. We measured the plasma levels of 50 soluble factors known to be involved in immune responses to viral diseases. For the first time, using a cell staining technique, we analyzed circulating lymphocytes from ZEBOV-infected patients. We found that fatal outcome in humans is associated with aberrant innate immunity characterized by a “cytokine storm,” with hypersecretion of numerous proinflammatory mediators and by the noteworthy absence of antiviral interferon. The adaptive response is globally suppressed, showing a massive loss of CD4 and CD8 lymphocytes and the immune mediators they produce. These findings may have important pathological and therapeutic implications

Role of Positron-Emission Tomography in Prognosis of Outcomes of High-Dose Chemotherapy with Autologous Hematopoietic Stem Cell Transplantation in Hodgkin’s Lymphoma

Aim. To perform a comparative analysis of the prognostic significance of positron-emission tomography (PET) with other prognostic factors of the efficacy of high-dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation (auto-HSCT) in patients with Hodgkin’s lymphoma. Methods. Data on 84 patients with Hodgkin’s lymphoma receiving treatment over the period from October 2007 till November 2015 were analyzed. The median age was 26.6 years (range: 10–62). The median follow-up was 25 months (range: 1–81 months). The prognostic significance of sex, response to the initial chemotherapy, time to relapse, second-line chemotherapy regimen type, B-symptoms, tumor size (>5 cm in cases of relapse prior to the HDCT), serum LDH and albumin levels, CT findings, the number of chemotherapy lines, conditioning regimen before the auto-HSCT, and the metabolic activity before the HDCT (PET1, n = 82) and after auto-HSCT (PET2, n = 57) was analyzed. Results. The two-year overall (OS) and event-free (EFS) survival rates were 70.6 % and 58.7%, respectively. Prognosis was the worst in patients with CT-confirmed lymphoma progression by the initiation of HDCT. In the presence of a CT-response, the PET status of lymphoma has a prognostic significance. The 2-year OS and EFS rates of PET1-negative and PET1-positive patients were 82 % vs. 62 % (p = 0.056) and 74 % vs. 44 % (p = 0.003), respectively. In PET2-negative and PET2-positive patients, the OS and EFS rates were 90 % vs. 65 % (p = 0.013) and 72 % vs. 52 % (p = 0.014), respectively. From the prognostic point of view, PET2 findings prevailed over PET1 findings. The multivariate analysis confirmed only PET2 significance for OS prediction. Conclusion. The tumor sensitivity to the chemotherapy assessed by the CT is the most important prognostic factor. In case of a positive CT dynamics, the achievement of PET1 or PET2 negativity before or after HDCT/auto-HSCT is a favorable prognostic factor. The worst prognosis was observed in patients with tumor metabolic activity before or after HDCT/auto-HSCT

Ectodomain shedding of the glycoprotein GP of Ebola virus

In this study, release of abundant amounts of the Ebola virus (EBOV) surface glycoprotein GP in a soluble form from virus-infected cells was investigated. We demonstrate that the mechanism responsible for the release of GP is ectodomain shedding mediated by cellular sheddases. Proteolytic cleavage taking place at amino-acid position D(637) removes the transmembrane anchor and liberates complexes consisting of GP(1) and truncated GP(2) (GP(2Δ)) subunits from the cell surface. We show that tumor necrosis factor α-converting enzyme (TACE), a member of the ADAM family of zinc-dependent metalloproteases, is involved in EBOV GP shedding. This finding shows for the first time that virus-encoded surface glycoproteins are substrates for ADAMs. Furthermore, we provide evidence that shed GP is present in significant amounts in the blood of virus-infected animals and that it may play an important role in the pathogenesis of infection by efficiently blocking the activity of virus-neutralizing antibodies