Overview of Rhabdo- and Filoviruses

Enveloped viruses with a negative-sense, single-stranded monopartite RNA genome have been classified into the order Mononegavirales. Five families of viruses that constitute the order are: Rhabdoviridae, Filoviridae, Paramyxoviridae, Bornaviridae and Nyamiviridae. Members of these families possess a helical nucleocapsid core containing the viral genome and a host-derived lipid envelope containing viral proteins. This introductory chapter provides a brief overview of the Rhabdoviridae and the Filoviridae, the two families of viruses that are the subject of this book. Many members of these two families are highly significant human and animal pathogens. The rationale and goal of the book is to provide the reader with the most recent information on the structure, genome organization and replication strategy, epidemiology, evolution and emergence, host response to infection, viral countermeasures as well as vaccines and antivirals against these pathogens. More detailed descriptions of these topics are presented in individual chapters of this book

Overview of Rhabdo- and Filoviruses

Enveloped viruses with a negative-sense, single-stranded monopartite RNA genome have been classified into the order Mononegavirales. Five families of viruses that constitute the order are: Rhabdoviridae, Filoviridae, Paramyxoviridae, Bornaviridae and Nyamiviridae. Members of these families possess a helical nucleocapsid core containing the viral genome and a host-derived lipid envelope containing viral proteins. This introductory chapter provides a brief overview of the Rhabdoviridae and the Filoviridae, the two families of viruses that are the subject of this book. Many members of these two families are highly significant human and animal pathogens. The rationale and goal of the book is to provide the reader with the most recent information on the structure, genome organization and replication strategy, epidemiology, evolution and emergence, host response to infection, viral countermeasures as well as vaccines and antivirals against these pathogens. More detailed descriptions of these topics are presented in individual chapters of this book

Binding and activation of host plasminogen on the surface of Francisella tularensis

<p>Abstract</p> <p>Background</p> <p><it>Francisella tularensis </it>(FT) is a gram-negative facultative intracellular coccobacillus and is the causal agent of a life-threatening zoonotic disease known as tularemia. Although FT preferentially infects phagocytic cells of the host, recent evidence suggests that a significant number of bacteria can be found extracellularly in the plasma fraction of the blood during active infection. This observation suggests that the interaction between FT and host plasma components may play an important role in survival and dissemination of the bacterium during the course of infection. Plasminogen (PLG) is a protein zymogen that is found in abundance in the blood of mammalian hosts. A number of both gram-positive and gram-negative bacterial pathogens have the ability to bind to PLG, giving them a survival advantage by increasing their ability to penetrate extracellular matrices and cross tissue barriers.</p> <p>Results</p> <p>We show that PLG binds to the surface of FT and that surface-bound PLG can be activated to plasmin in the presence of tissue PLG activator <it>in vitro</it>. In addition, using Far-Western blotting assays coupled with proteomic analyses of FT outer membrane preparations, we have identified several putative PLG-binding proteins of FT.</p> <p>Conclusions</p> <p>The ability of FT to acquire surface bound PLG that can be activated on its surface may be an important virulence mechanism that results in an increase in initial infectivity, survival, and/or dissemination of this bacterium <it>in vivo</it>.</p

Efficient generation of vesicular stomatitis virus (VSV)-pseudotypes bearing morbilliviral glycoproteins and their use in quantifying virus neutralising antibodies

Morbillivirus neutralising antibodies are traditionally measured using either plaque reduction neutralisation tests (PRNTs) or live virus microneutralisation tests (micro-NTs). While both test formats provide a reliable assessment of the strength and specificity of the humoral response, they are restricted by the limited number of viral strains that can be studied and often present significant biological safety concerns to the operator. In this study, we describe the adaptation of a replication-defective vesicular stomatitis virus (VSVΔG) based pseudotyping system for the measurement of morbillivirus neutralising antibodies. By expressing the haemagglutinin (H) and fusion (F) proteins of canine distemper virus (CDV) on VSVΔG pseudotypes bearing a luciferase marker gene, neutralising antibody titres could be measured rapidly and with high sensitivity. Further, by exchanging the glycoprotein expression construct, responses against distinct viral strains or species may be measured. Using this technique, we demonstrate cross neutralisation between CDV and peste des petits ruminants virus (PPRV). As an example of the value of the technique, we demonstrate that UK dogs vary in the breadth of immunity induced by CDV vaccination; in some dogs the neutralising response is CDV-specific while, in others, the neutralising response extends to the ruminant morbillivirus PPRV. This technique will facilitate a comprehensive comparison of cross-neutralisation to be conducted across the morbilliviruses

Rapid Screening for Entry Inhibitors of Highly Pathogenic Viruses under Low-Level Biocontainment

Emerging viruses including Nipah, Hendra, Lujo, and Junin viruses have enormous potential to spread rapidly. Nipah virus, after emerging as a zoonosis, has also evolved the capacity for human-to-human transmission. Most of the diseases caused by these pathogens are untreatable and require high biocontainment conditions. Universal methods for rapidly identifying and screening candidate antivirals are urgently needed. We have developed a modular antiviral platform strategy that relies on simple bioinformatic and genetic information about each pathogen. Central to this platform is the use of envelope glycoprotein cDNAs to establish multi-cycle replication systems under BSL2 conditions for viral pathogens that normally require BSL3 and BSL4 facilities. We generated monoclonal antibodies against Nipah G by cDNA immunization in rats, and we showed that these antibodies neutralize both Nipah and Hendra live viruses. We then used these effective Henipavirus inhibitors to validate our screening strategy. Our proposed strategy should contribute to the response capability for emerging infectious diseases, providing a way to initiate antiviral development immediately upon identifying novel viruses

The Genomic Signature of Crop-Wild Introgression in Maize

The evolutionary significance of hybridization and subsequent introgression has long been appreciated, but evaluation of the genome-wide effects of these phenomena has only recently become possible. Crop-wild study systems represent ideal opportunities to examine evolution through hybridization. For example, maize and the conspecific wild teosinte Zea mays ssp. mexicana, (hereafter, mexicana) are known to hybridize in the fields of highland Mexico. Despite widespread evidence of gene flow, maize and mexicana maintain distinct morphologies and have done so in sympatry for thousands of years. Neither the genomic extent nor the evolutionary importance of introgression between these taxa is understood. In this study we assessed patterns of genome-wide introgression based on 39,029 single nucleotide polymorphisms genotyped in 189 individuals from nine sympatric maize-mexicana populations and reference allopatric populations. While portions of the maize and mexicana genomes were particularly resistant to introgression (notably near known cross-incompatibility and domestication loci), we detected widespread evidence for introgression in both directions of gene flow. Through further characterization of these regions and preliminary growth chamber experiments, we found evidence suggestive of the incorporation of adaptive mexicana alleles into maize during its expansion to the highlands of central Mexico. In contrast, very little evidence was found for adaptive introgression from maize to mexicana. The methods we have applied here can be replicated widely, and such analyses have the potential to greatly informing our understanding of evolution through introgressive hybridization. Crop species, due to their exceptional genomic resources and frequent histories of spread into sympatry with relatives, should be particularly influential in these studies

Genetic Analysis of Central Carbon Metabolism Unveils an Amino Acid Substitution That Alters Maize NAD-Dependent Isocitrate Dehydrogenase Activity

Background: Central carbon metabolism (CCM) is a fundamental component of life. The participating genes and enzymes are thought to be structurally and functionally conserved across and within species. Association mapping utilizes a rich history of mutation and recombination to achieve high resolution mapping. Therefore, applying association mapping in maize (Zea mays ssp. mays), the most diverse model crop species, to study the genetics of CCM is a particularly attractive system. Methodology/Principal Findings: We used a maize diversity panel to test the CCM functional conservation. We found heritable variation in enzyme activity for every enzyme tested. One of these enzymes was the NAD-dependent isocitrate dehydrogenase (IDH, E.C. 1.1.1.41), in which we identified a novel amino-acid substitution in a phylogenetically conserved site. Using candidate gene association mapping, we identified that this non-synonymous polymorphism was associated with IDH activity variation. The proposed mechanism for the IDH activity variation includes additional components regulating protein level. With the comparison of sequences from maize and teosinte (Zea mays ssp. Parviglumis), the maize wild ancestor, we found that some CCM genes had also been targeted for selection during maize domestication. Conclusions/Significance: Our results demonstrate the efficacy of association mapping for dissecting natural variation in primary metabolic pathways. The considerable genetic diversity observed in maize CCM genes underlies heritable phenotypic variation in enzyme activities and can be useful to identify putative functional sites

A Spatio-Temporal Analysis of Matrix Protein and Nucleocapsid Trafficking during Vesicular Stomatitis Virus Uncoating

To study VSV entry and the fate of incoming matrix (M) protein during virus uncoating we used recombinant viruses encoding M proteins with a C-terminal tetracysteine tag that could be fluorescently labeled using biarsenical (Lumio) compounds. We found that uncoating occurs early in the endocytic pathway and is inhibited by expression of dominant-negative (DN) Rab5, but is not inhibited by DN-Rab7 or DN-Rab11. Uncoating, as defined by the separation of nucleocapsids from M protein, occurred between 15 and 20 minutes post-entry and did not require microtubules or an intact actin cytoskeleton. Unexpectedly, the bulk of M protein remained associated with endosomal membranes after uncoating and was eventually trafficked to recycling endosomes. Another small, but significant fraction of M distributed to nuclear pore complexes, which was also not dependent on microtubules or polymerized actin. Quantification of fluorescence from high-resolution confocal micrographs indicated that after membrane fusion, M protein diffuses across the endosomal membrane with a concomitant increase in fluorescence from the Lumio label which occurred soon after the release of RNPs into the cytoplasm. These data support a new model for VSV uncoating in which RNPs are released from M which remains bound to the endosomal membrane rather than the dissociation of M protein from RNPs after release of the complex into the cytoplasm following membrane fusion

The interpretations and uses of fitness landscapes in the social sciences

__Abstract__ This working paper precedes our full article entitled “The evolution of Wright’s (1932) adaptive field to contemporary interpretations and uses of fitness landscapes in the social sciences” as published in the journal Biology & Philosophy (http://link.springer.com/article/10.1007/s10539-014-9450-2). The working paper features an extended literature overview of the ways in which fitness landscapes have been interpreted and used in the social sciences, for which there was not enough space in the full article. The article features an in-depth philosophical discussion about the added value of the various ways in which fitness landscapes are used in the social sciences. This discussion is absent in the current working paper. Th

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges