Convergence of a common solution to broad ebolavirus neutralization by glycan cap directed human antibodies

Antibodies that target the glycan cap epitope on ebolavirus glycoprotein (GP) are common in the adaptive response of survivors. A subset is known to be broadly neutralizing, but the details of their epitopes and basis for neutralization is not well-understood. Here we present cryo-electron microscopy (cryo-EM) structures of several glycan cap antibodies that variably synergize with GP base-binding antibodies. These structures describe a conserved site of vulnerability that anchors the mucin-like domains (MLD) to the glycan cap, which we name the MLD-anchor and cradle. Antibodies that bind to the MLD-cradle share common features, including the use of IGHV1-69 and IGHJ6 germline genes, which exploit hydrophobic residues and form beta-hairpin structures to mimic the MLD-anchor, disrupt MLD attachment, destabilize GP quaternary structure and block cleavage events required for receptor binding. Our results collectively provide a molecular basis for ebolavirus neutralization by broadly reactive glycan cap antibodies

Chemokines cooperate with TNF to provide protective anti-viral immunity and to enhance inflammation

The role of cytokines and chemokines in anti-viral defense has been demonstrated, but their relative contribution to protective anti-viral responses in vivo is not fully understood. Cytokine response modifier D (CrmD) is a secreted receptor for TNF and lymphotoxin containing the smallpox virus-encoded chemokine receptor (SECRET) domain and is expressed by ectromelia virus, the causative agent of the smallpox-like disease mousepox. Here we show that CrmD is an essential virulence factor that controls natural killer cell activation and allows progression of fatal mousepox, and demonstrate that both SECRET and TNF binding domains are required for full CrmD activity. Vaccination with recombinant CrmD protects animals from lethal mousepox. These results indicate that a specific set of chemokines enhance the inflammatory and protective anti-viral responses mediated by TNF and lymphotoxin, and illustrate how viruses optimize anti-TNF strategies with the addition of a chemokine binding domain as soluble decoy receptors.We thank Javier Salguero for help with animal experimentation and immunohistochemistry, Rocío Martín and Carolina Sánchez for technical assistance and Daniel Rubio for discussions on the project. This work was funded by Grants from the Spanish Ministry of Economy and Competitiviness and European Union (European Regional Development’s Funds, FEDER) (grant SAF2015-67485-R), and the Wellcome Trust (grant 051087/Z97/Z). M.B.R.-A. and A. Alejo were recipients of a Ramón y Cajal Contract from the Spanish Ministry of Science and Innovation

Rapid isolation and profiling of a diverse panel of human monoclonal antibodies targeting the SARS-CoV-2 spike protein

Antibodies are a principal determinant of immunity for most RNA viruses and have promise to reduce infection or disease during major epidemics. The novel coronavirus SARS-CoV-2 has caused a global pandemic with millions of infections and hundreds of thousands of deaths to date1,2. In response, we used a rapid antibody discovery platform to isolate hundreds of human monoclonal antibodies (mAbs) against the SARS-CoV-2 spike (S) protein. We stratify these mAbs into five major classes on the basis of their reactivity to subdomains of S protein as well as their cross-reactivity to SARS-CoV. Many of these mAbs inhibit infection of authentic SARS-CoV-2 virus, with most neutralizing mAbs recognizing the receptor-binding domain (RBD) of S. This work defines sites of vulnerability on SARS-CoV-2 S and demonstrates the speed and robustness of advanced antibody discovery platforms

A cultura escolar em conflito: ensino técnico e matemática moderna em Portugal

Disponível em: http://www2.pucpr.br/reol/pb/index.php/dialogo?dd1=16276&dd99=view&dd98=pbO artigo estuda as transformações exigidas às escolas do ensino profissional português durante a reforma da matemática moderna que ocorrem a partir de finais dos anos 1960. Em primeiro lugar, traça um quadro das normas associadas às escolas técnicas portuguesas antes da reforma, recorrendo à legislação fundadora, aos manuais e a artigos de opinião de professores. Em segundo, detalha o debate que antecipou a introdução da reforma recorrendo a artigos e aopiniões expressas durante os cursos preparatórios, onde são notórias as pressões para mudanças na cultura escolar, especialmente nas suas representações, suscitadas pela nova matemática. Finalmente, observar-se como se materializou a reforma nos livros de texto da experiência

Antibody-Dependent Enhancement of Ebola Virus Infection by Human Antibodies Isolated from Survivors

Summary: Some monoclonal antibodies (mAbs) recovered from survivors of filovirus infections can protect against infection. It is currently unknown whether natural infection also induces some antibodies with the capacity for antibody-dependent enhancement (ADE). A panel of mAbs obtained from human survivors of filovirus infection caused by Ebola, Bundibugyo, or Marburg viruses was evaluated for their ability to facilitate ADE. ADE was observed readily with all mAbs examined at sub-neutralizing concentrations, and this effect was not restricted to mAbs with a particular epitope specificity, neutralizing capacity, or subclass. Blocking of specific Fcγ receptors reduced but did not abolish ADE that was associated with high-affinity binding antibodies, suggesting that lower-affinity interactions still cause ADE. Mutations of Fc fragments of an mAb that altered its interaction with Fc receptors rendered the antibody partially protective in vivo at a low dose, suggesting that ADE counteracts antibody-mediated protection and facilitates dissemination of filovirus infections. : In this paper, Kuzmina et al. demonstrate that filovirus antibodies from human survivors present at low concentrations are capable of enhancement of infection, suggesting that low levels of antibodies in humans may facilitate virus spread. The enhancement can be caused by antibodies of various epitope specificities, neutralizing capacities, and subclasses. Keywords: Ebola virus, filovirus, antibody, enhancement of infection, FC receptor, epitop

Asymmetric antiviral effects of ebolavirus antibodies targeting glycoprotein stem and glycan cap.

Recent studies suggest that some monoclonal antibodies (mAbs) specific for ebolavirus glycoprotein (GP) can protect experimental animals against infections. Most mAbs isolated from ebolavirus survivors appeared to target the glycan cap or the stalk region of the viral GP, which is the envelope protein and the only antigen inducing virus-neutralizing antibody response. Some of the mAbs were demonstrated to be protective in vivo. Here, a panel of mAbs from four individual survivors of ebolavirus infection that target the glycan cap or stem region were selected for investigation of the mechanisms of their antiviral effect. Comparative characterization of the inhibiting effects on multiple steps of viral replication was performed, including attachment, post-attachment, entry, binding at low pH, post-cleavage neutralization of virions, viral trafficking to endosomes, cell-to-cell transmission, viral egress, and inhibition when added early at various time points post-infection. In addition, Fc-domain related properties were characterized, including activation and degranulation of NK cells, antibody-dependent cellular phagocytosis and glycan content. The two groups of mAbs (glycan cap versus stem) demonstrated very different profiles of activities suggesting usage of mAbs with different epitope specificity could coordinate inhibition of multiple steps of filovirus infection through Fab- and Fc-mediated mechanisms, and provide a reliable therapeutic approach

In silico analysis of the structure of variable domains of mouse single-chain antibodies specific to the human recombinant interferon β1b

In silico analysis of the DNA encoding singlechain Fv antibodies (ScFv) specific to the human recombinant interferon β1b and α2b (rhIFNβ1b, rhIFNα2b) has been carried out. The V, D and J-gene segments, the complementaritydetermining (CDR) and framework (FR) regions, n-nucleotides as well as mutation rates which take place during the affinity maturation of the examined sequences have been determined. For the panel of ScFv against rhIFNβ1b isolated from an immune combinatorial cDNA library uniqueness of the CDRH3 loop by the length and amino acid composition has been shown. Multiple alignments with the nearest homologies from the NCBI databases have revealed that the sequences of ScFv obtained are new.Проведен in silico анализ структуры последовательностей ДНК, кодирующих специфические к интерферону β1b и α2b человека (rhIFN β1b, rhIFN α2b) одноцепочечные антитела (ScFv – single chain Fv): определены V, D и J сегменты, границы антиген связывающих (CDR) и каркасных (FR) участков, n нуклеотиды, а также величина мутационных процессов, которые имели место при аффинном дозревании последовательностей in vivo. Для представителей панели ScFv против rhIFN β1b, изолированных из иммунной комбинаторной библиотеки кДНК V генов, показана уникальность участка CDRH3 как по длине, так и по аминокислотному составу. Множественное выравнивание с ближайшими гомологами базы данных NCBI показало, что полученные нами последовательности ScFv являются новыми.Проведено in silico аналіз структури послідовностей ДНК, які кодують специфічні до рекомбінантного інтерферону β1b та α2b людини (rhIFN β1b, rhIFN-α2b) одноланцюгові антитіла (ScFv – single chain Fv): визначено V , D та J генні сегменти, межі антигензв’язувальних (CDR) та каркасних (FR) ділянок, n- нуклеотиди, а також величину мутаційних процесів, що мали місце при афінному дозріванні даних послідовностей in vivo. Для представників панелі ScFv проти rhIFN β1b, ізольованих з імунної комбінаторної бібліотеки кДНК V генів, показано унікальність ділянки CDRH3 як за довжиною, так і за амінокислотним складом. Множинне вирівнювання з найближчими гомологами бази даних NCBI показало, що одержані нами послідовності ScFv є новими

Multifunctional Pan-ebolavirus Antibody Recognizes a Site of Broad Vulnerability on the Ebolavirus Glycoprotein

Ebolaviruses cause severe disease in humans, and identification of monoclonal antibodies (mAbs) that are effective against multiple ebolaviruses are important for therapeutics development. Here we describe a distinct class of broadly neutralizing human mAbs with protective capacity against three ebolaviruses infectious for humans: Ebola (EBOV), Sudan (SUDV), and Bundibugyo (BDBV) viruses. We isolated mAbs from human survivors of ebolavirus disease and identified a potent mAb, EBOV-520, which bound to an epitope in the glycoprotein (GP) base region. EBOV-520 efficiently neutralized EBOV, BDBV, and SUDV and also showed protective capacity in relevant animal models of these infections. EBOV-520 mediated protection principally by direct virus neutralization and exhibited multifunctional properties. This study identified a potent naturally occurring mAb and defined key features of the human antibody response that may contribute to broad protection. This multifunctional mAb and related clones are promising candidates for development as broadly protective pan-ebolavirus therapeutic molecules