Electron Tomography Reveals the Steps in Filovirus Budding

The filoviruses, Marburg and Ebola, are non-segmented negative-strand RNA viruses causing severe hemorrhagic fever with high mortality rates in humans and nonhuman primates. The sequence of events that leads to release of filovirus particles from cells is poorly understood. Two contrasting mechanisms have been proposed, one proceeding via a “submarine-like” budding with the helical nucleocapsid emerging parallel to the plasma membrane, and the other via perpendicular “rocket-like” protrusion. Here we have infected cells with Marburg virus under BSL-4 containment conditions, and reconstructed the sequence of steps in the budding process in three dimensions using electron tomography of plastic-embedded cells. We find that highly infectious filamentous particles are released at early stages in infection. Budding proceeds via lateral association of intracellular nucleocapsid along its whole length with the plasma membrane, followed by rapid envelopment initiated at one end of the nucleocapsid, leading to a protruding intermediate. Scission results in local membrane instability at the rear of the virus. After prolonged infection, increased vesiculation of the plasma membrane correlates with changes in shape and infectivity of released viruses. Our observations demonstrate a cellular determinant of virus shape. They reconcile the contrasting models of filovirus budding and allow us to describe the sequence of events taking place during budding and release of Marburg virus. We propose that this represents a general sequence of events also followed by other filamentous and rod-shaped viruses

Comparative Efficacy Analysis of Mobilization and Collection of Autologous Hematopoietic Stem Cells in Patients with Lymphoproliferative Disorders and Multiple Sclerosis

Aim. Comparative efficacy analysis of autologous hematopoietic stem cells (HSC) prior to auto-HSCT in patients with lymphoproliferative disorders (LPDs) and multiple sclerosis (MS). Materials & Methods. The trial included 237 patients: 103 LPD and 134 MS patients. In 225 patients HSC mobilization involved only colony-stimulating factors (CSFs), in 12 patients chemotherapy (cyclophosphamide, etoposide) was combined with CSFs. On the intended date of cytapheresis all the patients were tested for CD34+ marker expression. Сytapheresis followed in the patients with CD34+ count more than 0.01 × 106/mL. Results. In 23 (22 %) LPD patients CD34+ count was too low for auto-HSCT (‘collection failure group’). Within this group 19 patients received CSF mobilization, and 4 patients received chemotherapy + CSF. Plerixafor was administered in 5 patients, in 4 of them a repeated mobilization also failed to collect enough cells. In 80 LPD patients the number of mobilized and collected CD34+ cells was sufficient for auto-HSCT (‘collection success group’). Within this group 77 patients received auto-HSCT, 74 patients were treated with CSF mobilization, 6 patients received chemotherapy + CSF, and in 11 patients plerixafor was administered. Median total number of CD34+ cells in the ‘collection success group’ was 2.7 × 106/kg. All 134 MS patients had enough CD34+ cells for auto-HSCT. All of them received CSF mobilization. Median total number of CD34+ cells in the MS group was 2.34 × 106/kg. Potential risk factors for HSC mobilization failure in LPDs were evaluated. They included age, gender, prior radiotherapy, number of antitumor treatment lines prior to auto-HSCT, clinical response prior to auto-HSCT (complete/partial remission or stabilization), and HSC mobilization regimen. These factors with the exception of gender were not associated with mobilization failure parameters. The worst mobilization outcomes were reported in male patients. Conclusion. In 22 % of LPD patients the planned high-dose chemotherapy and auto-HSCT failed due to insufficient counts of autologous CD34+ cells in apheresis product. Male gender can be considered to be a prognostic factor of mobilization failure in LPDs

Outcome of Classical Hodgkin’s Lymphoma Treatment Based on High-Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation: The Experience in the NI Pirogov Russian National Medical Center of Surgery

Aim. To estimate the long-term outcome of the programmed treatment of classical Hodgkin’s lymphoma (cHL) including high-dose chemotherapy (HDCT) and autologous hematopoietic stem cell transplantation (auto-HSCT) as well as the effect of various factors on the achieved results in a single-center study. Materials & Methods. In the A.A. Maksimov Clinical Center of Hematology and Cellular Therapy of the NI Pirogov Russian National Medical Center of Surgery 260 cHL patients received HDCT combined with auto-HSCT within the period from December 2006 to March 2017. The median age was 29 years (range 17–62). The study included 40 % men (n = 104), and 60 % women (n = 156). The median pretransplantation chemotherapy line was 3 (range 2–9). At this stage, prior to auto-HSCT, complete remission (CR) rate was 26.5 %, partial remission (PR) rate was 52.3 %, disease stabilisation rate was 13.5 %. HDCT with auto-HSCT was applied beyond progression as a salvage therapy in 7.7 % of patients. In 79.6 % of patients the standard BEAM and CBV conditioning regimens were used. Results. After HDCT combined with auto-HSCT overall 5-year survival (OS) of 260 cHL patients was 74 %, and 5-year progression-free survival (PFS) was 48 %, which corresponds to the results of some international studies. 5-year OS rates were significantly higher after HDCT and auto-HSCT performed during the first CR or PR (85 %) vs the second and subsequent CR and PR (71 %). Neither gender (p = 0.4) nor ECOG status (p = 0.2) effects on OS and PFS were revealed. 5-year OS rates were significantly higher after HDCT and auto-HSCT performed during CR or PR (82 %) vs disease stabilisation and progression (54 %) as well as upon achieving CR (93 %) vs PR (77 %). Conclusion. In cHL tumor sensitivity to chemotherapy is the essential indication for HDCT combined with auto-HSCT. The optimal time for HDCT and auto-HSCT in cHL is the first CR/PR, and the best treatment outcome is achieved in patients with complete response prior to HDCT and auto-HSCT

Late Replication Domains in Polytene and Non-Polytene Cells of Drosophila melanogaster

In D. melanogaster polytene chromosomes, intercalary heterochromatin (IH) appears as large dense bands scattered in euchromatin and comprises clusters of repressed genes. IH displays distinctly low gene density, indicative of their particular regulation. Genes embedded in IH replicate late in the S phase and become underreplicated. We asked whether localization and organization of these late-replicating domains is conserved in a distinct cell type. Using published comprehensive genome-wide chromatin annotation datasets (modENCODE and others), we compared IH organization in salivary gland cells and in a Kc cell line. We first established the borders of 60 IH regions on a molecular map, these regions containing underreplicated material and encompassing ∼12% of Drosophila genome. We showed that in Kc cells repressed chromatin constituted 97% of the sequences that corresponded to IH bands. This chromatin is depleted for ORC-2 binding and largely replicates late. Differences in replication timing between the cell types analyzed are local and affect only sub-regions but never whole IH bands. As a rule such differentially replicating sub-regions display open chromatin organization, which apparently results from cell-type specific gene expression of underlying genes. We conclude that repressed chromatin organization of IH is generally conserved in polytene and non-polytene cells. Yet, IH domains do not function as transcription- and replication-regulatory units, because differences in transcription and replication between cell types are not domain-wide, rather they are restricted to small “islands” embedded in these domains. IH regions can thus be defined as a special class of domains with low gene density, which have narrow temporal expression patterns, and so displaying relatively conserved organization

Biochemical Markers of Cardiotoxicity of High-Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation in Patients with Malignant Lymphoproliferative Disorders

Background. High-dose chemotherapy (HDCT) with autologous hematopoietic stem cells transplantation (auto-HSCT) is an effective therapeutic option for patients with Hodgkin’s lymphoma and aggressive non-Hodgkin’s lymphomas in those cases, when the standard chemotherapy combined with the radiation therapy proves to be ineffective. The HDCT and auto-HSCT are also basic treatment options for multiple myeloma. However, toxic effects of the transplantation, including cardiotoxicity, may significantly worsen the prognosis of patients who receive this treatment. Aim. To evaluate changes in biochemical markers of cardiotoxicity (troponin and N-terminal prohormone of brain natriuretic peptide (NT-proBNP)) in patients with malignant lymphomas (receiving HDCT and auto-HSCT). Materials & Methods. 157 patients were enrolled in the study. The sensitivity threshold of the troponin T test was 0.1 ng/mL and troponin I 0.001 ng/mL (highly sensitive troponin). Troponin T (conventional troponin) was measured in 56 patients, troponin I was assessed in 101 patients. Serum troponin levels were evaluated before the conditioning, on D0, D+7, and D+12. The level of NT-proBNP was assessed before the conditioning, on D0 and D+12. Results. Increased troponin T level was observed in 2 of 56 patients (3.6 %), increased troponin I level — in 27 of 101 patients (26.7 %) (p < 0.01). Troponin levels were within normal limits in all patients at admission. Troponin T levels increased only on D+7. Troponin I level increased in 4 patients (4 %) on D0, in 17 patients (16.8 %) on D+7 and in 11 patients (10.9 %) on D+12. The median concentration of troponin I was 0.215 ng/mL after HDCT completion, 0.74 ng/mL on D+7 and 0.21 ng/mL on D+12. No cases of myocardial infarction were observed. NT-proBNP levels in most patients were within normal limits at admission (median level 79.2 pg/mL). The situation changed significantly after conditioning: in most patients the level was almost twice as high as the upper normal limit (medial 240.6 pg/mL). Significant differences in levels of NT-proBNP (p < 0.05) were observed at comparison of data before conditioning and D0, and before conditioning and D+12. Conclusion. The data obtained confirm a significant impact of HDCT and auto-HSCT on the cardiovascular system of patients with malignant lymphomas. Further studies and observation of the patients are needed to clarify the prognostic significance of the findings related to cardiotoxicity (in particular, congestive heart failure)

Hands on Native Mass Spectrometry Analysis of Multi-protein Complexes

International audienceBy maintaining intact multi-protein complexes in the gas-phase, native mass spectrometry provides their molecular weight with very good accuracy compared to other methods (typically native PAGE or SEC-MALS) [1]. Besides, heterogeneous samples, both in terms of oligomeric states and ligand-bound species can be fully characterized. Here we thoroughly describe the analysis of several oligomeric protein complexes ranging from a 16 kDa dimer to a 801 kDa tetradecameric complex on different instrumental setups