Cathepsin L Functionally Cleaves the Severe Acute Respiratory Syndrome Coronavirus Class I Fusion Protein Upstream of Rather than Adjacent to the Fusion Peptide▿

Unlike other class I viral fusion proteins, spike proteins on severe acute respiratory sydrome coronavirus virions are uncleaved. As we and others have demonstrated, infection by this virus depends on cathepsin proteases present in endosomal compartments of the target cell, suggesting that the spike protein acquires its fusion competence by cleavage during cell entry rather than during virion biogenesis. Here we demonstrate that cathepsin L indeed activates the membrane fusion function of the spike protein. Moreover, cleavage was mapped to the same region where, in coronaviruses carrying furin-activated spikes, the receptor binding subunit of the protein is separated from the membrane-anchored fusion subunit

Increased risk of ischemic stroke after radiotherapy on the neck in patients younger than 60 years

PURPOSE: To estimate the risk of ischemic stroke in patients irradiated for head and neck tumors. PATIENTS AND METHODS: The incidence of ischemic stroke was determined in 367 patients with head and neck tumors (162 larynx carcinomas, 114 pleomorphic adenomas, and 91 parotid carcinomas) who had been treated with local radiotherapy (RT) at an age younger than 60 years. Relative risk (RR) of ischemic stroke was determined by comparison with population rates from a stroke-incidence register, adjusted for sex and age. Other risk factors for stroke (hypertension, smoking, hypercholesterolemia, diabetes mellitus [DM]) were registered. The median follow-up time after RT was 7.7 years (3,011 person-years of follow-up). RESULTS: Fourteen cases of stroke occurred (expected, 2.5; RR, 5.6; 95% confidence interval [CI], 3.1 to 9.4): eight in patients with laryngeal carcinoma (expected,1.56; RR, 5.1; 95% CI, 2.2 to 10.1), four in pleomorphic adenoma patients (expected, 0.71; RR, 5.7; 95% CI, 1.5 to 14.5), and two in parotid carcinoma patients (expected, 0.24; RR, 8.5, 95% CI, 1.0 to 30.6). Five of six strokes in patients irradiated for a parotid tumor occurred at the ipsilateral side. Analysis of other risk factors for cerebrovascular disease showed hypertension and DM to cause an increase of the RR after RT. After more than 10 years' follow-up, the RR was 10.1 (95% CI, 4.4 to 20.0). The 15-year cumulative risk of stroke after RT on the neck was 12.0% (95% CI, 6.5% to 21.4%). CONCLUSION: This is the first study to demonstrate an increased risk of stroke after RT on the neck. During medical follow-up, preventive measures should be taken to reduce the impact of the risk factors for cerebrovascular disease, to decrease stroke in these patient

Cryo-electron tomography of mouse hepatitis virus: Insights into the structure of the coronavirion

Coronaviruses are enveloped viruses containing the largest reported RNA genomes. As a result of their pleomorphic nature, our structural insight into the coronavirion is still rudimentary, and it is based mainly on 2D electron microscopy. Here we report the 3D virion structure of coronaviruses obtained by cryo-electron tomography. Our study focused primarily on the coronavirus prototype murine hepatitis virus (MHV). MHV particles have a distinctly spherical shape and a relatively homogenous size (≈85 nm envelope diameter). The viral envelope exhibits an unusual thickness (7.8 ± 0.7 nm), almost twice that of a typical biological membrane. Focal pairs revealed the existence of an extra internal layer, most likely formed by the C-terminal domains of the major envelope protein M. In the interior of the particles, coiled structures and tubular shapes are observed, consistent with a helical nucleocapsid model. Our reconstructions provide no evidence of a shelled core. Instead, the ribonucleoprotein seems to be extensively folded onto itself, assuming a compact structure that tends to closely follow the envelope at a distance of ≈4 nm. Focal contact points and thread-like densities connecting the envelope and the ribonucleoprotein are revealed in the tomograms. Transmissible gastroenteritis coronavirion tomograms confirm all the general features and global architecture observed for MHV. We propose a general model for the structure of the coronavirion in which our own and published observations are combined

Quantitative and qualitative flow cytometric analysis of nanosized cell-derived membrane vesicles

Nanosized cell-derived membrane vesicles are increasingly recognized as therapeutic vehicles and high-potential biomarkers for several diseases. Currently available methods allow bulk analysis of vesicles but are not suited for accurate quantification and fail to reveal phenotypic heterogeneity in membrane vesicle populations. For such analyses, single vesicle-based, multiparameter, high-throughput methods are needed. We developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized membrane vesicles. Proof of principle was obtained by single-particle analysis of virions and liposomes. Further validation was obtained by quantification of cell-derived nanosized membrane vesicles from cell cultures and body fluids. An important aspect was that the technology was extended to detect specific proteins on individual vesicles. This allowed identification of exosome subsets and phenotyping of individual exosomes produced by dendritic cells (DCs) undergoing different modes of activation. The described technology allows quantitative, multiparameter, and high-throughput analysis of a wide variety of nanosized particles and has broad applications. From the Clinical Editor: The authors developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized cell-derived membrane vesicles that are increasingly recognized both as therapeutic vehicles and high-potential biomarkers for several diseases. A high throughput, easily available, and sensitive detection method such as the one discussed here is a critically important prerequisite for further refinements of this technology

Coronavirus escape from heptad repeat 2 (HR2)-derived peptide entry inhibition as a result of mutations in the HR1 domain of the spike fusion protein

Peptides based on heptad repeat (HR) domains of class I viral fusion proteins are considered promising antiviral drugs targeting virus cell entry. We have analyzed the evolution of the mouse hepatitis coronavirus during multiple passaging in the presence of an HR2-based fusion inhibitor. Drug-resistant variants emerged as a result of multiple substitutions in the spike fusion protein, notably within a 19-residue segment of the HR1 region. Strikingly, one mutation, an A1006V substitution, which consistently appeared first in four independently passaged viruses, was the main determinant of the resistance phenotype, suggesting that only limited options exist for escape from the inhibitory effect of the HR2 peptide

Quantitative and qualitative flow cytometric analysis of nanosized cell-derived membrane vesicles

Nanosized cell-derived membrane vesicles are increasingly recognized as therapeutic vehicles and high-potential biomarkers for several diseases. Currently available methods allow bulk analysis of vesicles but are not suited for accurate quantification and fail to reveal phenotypic heterogeneity in membrane vesicle populations. For such analyses, single vesicle-based, multiparameter, high-throughput methods are needed. We developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized membrane vesicles. Proof of principle was obtained by single-particle analysis of virions and liposomes. Further validation was obtained by quantification of cell-derived nanosized membrane vesicles from cell cultures and body fluids. An important aspect was that the technology was extended to detect specific proteins on individual vesicles. This allowed identification of exosome subsets and phenotyping of individual exosomes produced by dendritic cells (DCs) undergoing different modes of activation. The described technology allows quantitative, multiparameter, and high-throughput analysis of a wide variety of nanosized particles and has broad applications. From the Clinical Editor: The authors developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized cell-derived membrane vesicles that are increasingly recognized both as therapeutic vehicles and high-potential biomarkers for several diseases. A high throughput, easily available, and sensitive detection method such as the one discussed here is a critically important prerequisite for further refinements of this technology

Impact of the boost dose of 10 Gy versus 26 Gy in patients with early stage breast cancer after a microscopically incomplete lumpectomy: 10-year results of the randomised EORTC boost trial

Purpose: To assess the impact of the boost dose in patients with involved surgical margins. Patients and methods: In the EORTC "boost versus no boost" trial, 251 patients with a microscopically incomplete turnout excision were randomised to receive either a low boost dose of 10 Gy (126 patients) OF a high boost dose of 26 Gy (125 patients). Overall survival and the cumulative incidence of local recurrence as first event were compared by Logrank and Gray test, respectively (2-sided alpha = 0.05), with a median follow-up of 11.3 years. The planned sample size was 660 patients, but only 251 were recruited. Results: The median age at randomisation was 54 years. Thirty-seven patient initially relapsed locally. At 10 years, the cumulative incidence of local recurrence was 17.5% (95% CI: 10.4-24.6%) versus 10.8% (95% CI: 5.2-16.4%) for the low and high boost dose groups, respectively (HR = 0.83, 95% CI: 0.43-1.57, Gray p > 0.1). Overall, 64 patients have died (25.5%), 47 of them of breast cancer, without a difference in duration of survival between the two groups (HR = 0.97, 95% CI = 0.59-1.5, p > 0.1). Severe fibrosis was palpated in the breast in 1% versus 5% and in the boost area in 3% versus 13% in the low and high boost dose groups, respectively. Conclusions: There was no statistically significant difference in local control or survival between the high boost dose of 26 Gy and the low boost dose of 10 Gy in patients with microscopically incomplete excision of early breast cancer. Fibrosis, however, was noted significantly more frequently in cases treated with the high boost dose. (C) 2008 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 90 (2009) 80-8

Recombinant soluble, multimeric HA and NA exhibit distinctive types of protection against pandemic swine-origin 2009 A(H1N1) influenza virus infection in ferrets

The emergence and subsequent swift and global spread of the swine-origin influenza virus A(H1N1) in 2009 once again emphasizes the strong need for effective vaccines that can be developed rapidly and applied safely. With this aim, we produced soluble, multimeric forms of the 2009 A(H1N1) HA (sHA3) and NA (sNA4) surface glycoproteins using a virus-free mammalian expression system and evaluated their efficacy as vaccines in ferrets. Immunization twice with 3.75-μg doses of these antigens elicited strong antibody responses, which were adjuvant dependent. Interestingly, coadministration of both antigens strongly enhanced the HA-specific but not the NA-specific responses. Distinct patterns of protection were observed upon challenge inoculation with the homologous H1N1 virus. Whereas vaccination with sHA3dramatically reduced virus replication (e.g., by lowering pulmonary titers by about 5 log10units), immunization with sNA4markedly decreased the clinical effects of infection, such as body weight loss and lung pathology. Clearly, optimal protection was achieved by the combination of the two antigens. Our observations demonstrate the great vaccine potential of multimeric HA and NA ectodomains, as these can be easily, rapidly, flexibly, and safely produced in high quantities. In particular, our study underscores the underrated importance of NA in influenza vaccination, which we found to profoundly and specifically contribute to protection by HA. Its inclusion in a vaccine is likely to reduce the HA dose required and to broaden the protective immunity. Copyrigh

Recombinant soluble, multimeric HA and NA exhibit distinctive types of protection against pandemic swine-origin 2009 A(H1N1) influenza virus infection in ferrets

The emergence and subsequent swift and global spread of the swine-origin influenza virus A(H1N1) in 2009 once again emphasizes the strong need for effective vaccines that can be developed rapidly and applied safely. With this aim, we produced soluble, multimeric forms of the 2009 A(H1N1) HA (sHA3) and NA (sNA4) surface glycoproteins using a virus-free mammalian expression system and evaluated their efficacy as vaccines in ferrets. Immunization twice with 3.75-μg doses of these antigens elicited strong antibody responses, which were adjuvant dependent. Interestingly, coadministration of both antigens strongly enhanced the HA-specific but not the NA-specific responses. Distinct patterns of protection were observed upon challenge inoculation with the homologous H1N1 virus. Whereas vaccination with sHA3 dramatically reduced virus replication (e.g., by lowering pulmonary titers by about 5 log10 units), immunization with sNA4 markedly decreased the clinical effects of infection, such as body weight loss and lung pathology. Clearly, optimal protection was achieved by the combination of the two antigens. Our observations demonstrate the great vaccine potential of multimeric HA and NA ectodomains, as these can be easily, rapidly, flexibly, and safely produced in high quantities. In particular, our study underscores the underrated importance of NA in influenza vaccination, which we found to profoundly and specifically contribute to protection by HA. Its inclusion in a vaccine is likely to reduce the HA dose required and to broaden the protective immunit