Isolation and characterization of phage display-derived scFv antibodies against human parechovirus 1 VP0 protein

Human parechoviruses (PeVs) are common viruses that are associated with a variety of diseases from mild gastrointestinal and respiratory symptoms to severe central nervous system infections. Until now there has not been antibodies for visualizing parechovirus infection. We used E. coli recombinant PeV-A1-VP0 protein as a target in phage display single chain variable fragment (scFv) antibody library panning. Three rounds of panning allowed identification and isolation of several candidate scFv clones, which tested positive in enzyme-linked immunosorbent assay (ELISA) against VP0. Three scFv clones (scFv-55, -59 and -71) with different CDR-3 sequences were further purified and tested in ELISA, Western blot and immunofluorescence microscopy (IFA) against a set of PeV-A1 isolates and a few isolates representing PeV types 2–6. In IFA, all three scFv binders recognized twenty PeV-A1 isolates. ScFv-55 and -71 also recognized clinical representatives of PeV types 1–6 both in IFA and in capture ELISA, while scFv-59 only recognized PeV-A1, -A2 and -A6. PeV-A1-VP0 (Harris strain) sequence was used to generate a peptide library, which allowed identification of a putative unique conformational antibody epitope with fully conserved flanking regions and a more variable core VVTYDSKL, shared between the scFv antibodies. Sequencing of the VP0 region of virus samples and sequence comparisons against parechoviral sequences in GenBank revealed 107 PeV-A1, -A3, -A8, -A17, -A (untyped) sequences with this exact epitope core sequence, which was most dominant among PeV-A1 isolates. These data suggest the first-time isolation of broad range phage display antibodies against human parechoviruses that may be used in diagnostic antibody development.

Cytolytic Properties and Genome Analysis of Rigvir® Oncolytic Virotherapy Virus and Other Echovirus 7 Isolates

Rigvir® is a cell-adapted, oncolytic virotherapy enterovirus, which derives from an echovirus 7 (E7) isolate. While it is claimed that Rigvir® causes cytolytic infection in several cancer cell lines, there is little molecular evidence for its oncolytic and oncotropic potential. Previously, we genome-sequenced Rigvir® and five echovirus 7 isolates, and those sequences are further analyzed in this paper. A phylogenetic analysis of the full-length data suggested that Rigvir® was most distant from the other E7 isolates used in this study, placing Rigvir® in its own clade at the root of the phylogeny. Rigvir® contained nine unique mutations in the viral capsid proteins VP1-VP4 across the whole data set, with a structural analysis showing six of the mutations concerning residues with surface exposure on the cytoplasmic side of the viral capsid. One of these mutations, E/Q/N162G, was located in the region that forms the contact interface between decay-accelerating factor (DAF) and E7. Rigvir® and five other isolates were also subjected to cell infectivity assays performed on eight different cell lines. The used cell lines contained both cancer and non-cancer cell lines for observing Rigvir®'s claimed properties of being both oncolytic and oncotropic. Infectivity assays showed that Rigvir® had no discernable difference in the viruses' oncolytic effect when compared to the Wallace prototype or the four other E7 isolates. Rigvir® was also seen infecting non-cancer cell lines, bringing its claimed effect of being oncotropic into question. Thus, we conclude that Rigvir®'s claim of being an effective treatment against multiple different cancers is not warranted under the evidence presented here. Bioinformatic analyses do not reveal a clear mechanism that could elucidate Rigvir®'s function at a molecular level, and cell infectivity tests do not show a discernable difference in either the oncolytic or oncotropic effect between Rigvir® and other clinical E7 isolates used in the study.

Special Issue: Virus Receptors and Viral Tropism

Cell surface receptors play a key role in a virus' ability to recognize and invade cells and tissues, which basically defines viral pathogenicity [...].

Monoclonal antibody against VP0 recognizes a broad range of human parechoviruses

Parechoviruses (PeVs) are common viruses that cause mild gastrointestinal or respiratory symptoms to severe central nervous system infections. In infants, parechovirus infection is one of the leading causes of life-threatening viral disease. High-quality antibodies with broad binding specificities are essential to improve accurate parechovirus diagnosis in diagnostic laboratories. Such antibodies have potential in the development of rapid antigen detection assay against PeVs. In the present study, VP4 and VP2 genes from human parechovirus A1 (PeV-A1) were cloned and VP0 fusion protein produced to develop monoclonal antibodies against PeVs. Two pan-parechovirus antibodies, one IgG and one IgM isotype, were isolated. The properties of IgG1/κ monoclonal (designated as Mab-PAR-1) was studied further. Mab-PAR-1 was shown to be functional in western blot against denatured recombinant protein and viral particles. In immunofluorescence assay, the antibody tested positive for nineteen PeV-A1 isolates while showing no cross-reactivity to fourteen entero- and rhinovirus types. In addition, Mab-PAR-1 showed positive reactivity against five other cultivable parechovirus types 2-6. A unique Mab-PAR-1 epitope located in the junction of the three capsid proteins VP0, VP1, and VP3 was identified using a peptide library screen. This study demonstrates that PeV-A1-VP0 protein is functional antigen for developing monoclonal antibody for diagnosis of broad range of parechovirus infections.

Recommendations for the introduction of metagenomic high-throughput sequencing in clinical virology, part I: Wet lab procedure

Metagenomic high-throughput sequencing (mHTS) is a hypothesis-free, universal pathogen detection technique for determination of the DNA/RNA sequences in a variety of sample types and infectious syndromes. mHTS is still in its early stages of translating into clinical application. To support the development, implementation and standardization of mHTS procedures for virus diagnostics, the European Society for Clinical Virology (ESCV) Network on Next-Generation Sequencing (ENNGS) has been established. The aim of ENNGS is to bring together professionals involved in mHTS for viral diagnostics to share methodologies and experiences, and to develop application recommendations. This manuscript aims to provide practical recommendations for the wet lab procedures necessary for implementation of mHTS for virus diagnostics and to give recommendations for development and validation of laboratory methods, including mHTS quality assurance, control and quality assessment protocols.

Aseptic meningitis outbreak associated with echovirus 4 in Northern Europe in 2013-2014

Picornaviruses (family Picornaviridae) are small, nonenveloped, positive-sense, single-stranded RNA viruses. The members of this family are currently classified into 47 genera and 110 species. Of picornaviruses, entero- and parechoviruses are associated with aseptic meningitis. They are transmitted via fecal-oral and respiratory routes, and occasionally, these viruses may cause a brief viremia and gain access to central nervous system (CNS). During the diagnostic screening of entero- and parechovirus types in Finland in year 2013-14, we detected a cluster of echovirus 4 (E4) infections in young adults and adolescents. As E4 is infrequently detected in Finland, we contacted several Northern and Central European laboratories that conduct routine surveillance for enteroviruses and, for those who have had E4 cases, we send a query for E4 sequences and data. Here we report CNS infections caused by E4 in Finland, Sweden, Norway, Denmark, Iceland and Germany in 2013 and 2014, and show that the E4 detected in these countries form a single lineage. In contrast, E4 strains circulating in these countries preceding the year 2013, and those circulating elsewhere in Europe during 2013-2014, formed several independent clusters.

Recombination Events and Conserved Nature of Receptor Binding Motifs in Coxsackievirus A9 Isolates

Coxsackievirus A9 (CVA9) is an enterically transmitted enterovirus and one of the most pathogenic type among human enteroviruses. CVA9 isolates use a distinctive RGD (Arg-Gly-Asp) motif within VP1 capsid protein that defines its ability to bind to integrin receptor(s) for cellular entry. To investigate CVA9 evolution and pathogenicity, genetic relationships and recombination events were analyzed between 54 novel clinical isolates of CVA9, as well as 21 previously published full length CVA9 sequences from GenBank. Samples were investigated by partial sequencing of the novel VP1 and 3Dpol genes, as well as including the corresponding areas from GenBank sequences. Phylogenetic analyses were combined with clinical data in a further attempt to analyze whether sequence evolution reflects CVA9 pathogenicity in the phylogenies. Furthermore, VP1 gene was also analyzed for receptor binding sites including the RGD motif and the putative heparan sulfate (HS) site. Analysis of the 559-nucleotide-long VP1 sequences identified six clades. Although most of the strains within each clade showed geographical clustering, the grouping pattern of the isolates in the analysis of the VP1 gene was strikingly different from grouping of 3Dpol, which suggests that recombination events may have occurred in the region encoding the nonstructural proteins. Inclusion of clinical data did not provide any evidence of symptom based phylogenetic clustering of CVA9 isolates. Amino acid sequence analysis of the VP1 polypeptide demonstrated that the RGD motif was fully conserved among the isolates while the putative HS binding site was only found in one isolate. These data suggest that integrin binding is essential for virus tropism, but do not explain the symptom repertoire.

Progress in human picornavirus research: New findings from the AIROPico consortium

Several research groups in Europe are active on different aspects of human picornavirus research. The AIROPico (Academia-Industry R&D Opportunities for Picornaviruses) consortium combined the disciplines of pathogenesis, diagnostics and therapy development in order to fill the gaps in our understanding of how picornaviruses cause human disease and how to combat them. AIROPico was the first EU consortium dedicated to human picornavirus research and development, and has largely accelerated and improved R&D on picornavirus biology, diagnostics and therapy. In this article, we present the progress on pathogenesis, diagnostics and treatment strategy developments for human picornaviruses resulting from the structured, translational research approach of the AIROPico consortium. We here summarize new insights in protection against infection by maternal or cross-protective antibodies, the visualisation of interactions between virus and neutralizing antibodies by cryoEM structural imaging, and the outcomes from a picornavirus-infected human 3D organoid. Progress in molecular detection and a fast typing assay for rhinovirus species are presented, as well as the identification of new compounds potentially interesting as therapeutic compounds.

Detection of human rhinoviruses by reverse transcription strand invasion based amplification method (RT-SIBA)

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Diagnosis of RV is extremely challenging due to genetic and serological variability within the RV serotypes.

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We report a novel isothermal nucleic acid amplification method for the detection of RV.

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The method, RT-SIBA, detected RV in clinical specimens with high analytical sensitivity and specificity.

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The method will facilitate prompt diagnosis of infection and thereby improving patient care.

Background: Rhinovirus (RV), a major cause of respiratory infection in humans, imposes an enormous economic burden due to the direct and indirect costs associated with the illness. Accurate and timely diagnosis is crucial for deciding the appropriate clinical approach and minimizing unnecessary prescription of antibiotics. Diagnosis of RV is extremely challenging due to genetic and serological variability among its numerous types and their similarity to enteroviruses.

Objective: We sought to develop a rapid nucleic acid test that can be used for the detection of Rhinovirus within both laboratory and near patient settings.

Study design: We developed and evaluated a novel isothermal nucleic acid amplification method called Reverse Transcription Strand Invasion-Based Amplification (RT-SIBA) to rapidly detect Rhinovirus from clinical specimens.

Result: The method, RT-SIBA, detected RV in clinical specimens with high analytical sensitivity (96%) and specificity (100%). The time to positive result was significantly shorter for the RV RT-SIBA assay than for a reference RV nucleic acid amplification method (RT-qPCR).

Conclusion: The rapid detection time of the RV SIBA assay, as well as its compatibility with portable instruments, will facilitate prompt diagnosis of infection and thereby improve patient care.

Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells

Background

Coxsackievirus A9 (CV-A9) is a pathogenic enterovirus type within the family Picornaviridae. CV-A9 infects A549 human epithelial lung carcinoma cells by attaching to the αVβ6 integrin receptor through a highly conserved Arg-Gly-Asp (RGD) motif, which is located at the exposed carboxy-terminus of the capsid protein VP1 detected in all studied clinical isolates. However, genetically-modified CV-A9 that lacks the RGD motif (CV-A9-RGDdel) has been shown to be infectious in some cell lines but not in A549, suggesting that RGD-mediated integrin binding is not always essential for efficient entry of CV-A9.

Methods

Two cell lines, A549 and SW480, were used in the study. SW480 was the study object for the integrin-independent entry and A549 was used as the control for integrin-dependent entry. Receptor levels were quantitated by cell sorting and quantitative PCR. Antibody blocking assay and siRNA silencing of receptor-encoding genes were used to block virus infection. Peptide phage display library was used to identify peptide binders to CV-A9. Immunofluorescence and confocal microscopy were used to visualize the virus infection in the cells.

Results

We investigated the receptor use and early stages of CV-A9 internalization to SW480 human epithelial colon adenocarcinoma cells. Contrary to A549 infection, we showed that both CV-A9 and CV-A9-RGDdel internalized into SW480 cells and that function-blocking anti-αV integrin antibodies had no effect on the binding and entry of CV-A9. Whereas siRNA silencing of β6 integrin subunit had no influence on virus infection in SW480, silencing of β2-microglobulin (β2M) inhibited the virus infection in both cell lines. By using a peptide phage display screening, the virus-binding peptide identical to the N-terminal sequence of HSPA5 protein was identified and shown to block the virus infection in both A549 and SW480 cell lines. HSPA5 was also found to co-localize with CV-A9 at the SW480 cell periphery during the early stages of infection by confocal microscopy.

Conclusions

The data suggest that while αVβ6 integrin is essential for CV-A9 in A549 cell line, it is not required in SW480 cell line in which β2M and HSPA5 alone are sufficient for CV-A9 infection. This suggests that the choice of CV-A9 receptor(s) is dependent on the tissue/cellular environment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0619-y) contains supplementary material, which is available to authorized users.

Human Parechovirus 1 Infection Occurs via αVβ1 Integrin

Human parechovirus 1 (HPeV-1) (family Picornaviridae) is a global cause of pediatric respiratory and CNS infections for which there is no treatment. Although biochemical and in vitro studies have suggested that HPeV-1 binds to αVβ1, αVβ3 and αVβ6 integrin receptor(s), the actual cellular receptors required for infectious entry of HPeV-1 remain unknown. In this paper we analyzed the expression profiles of αVβ1, αVβ3, αVβ6 and α5β1 in susceptible cell lines (A549, HeLa and SW480) to identify which integrin receptors support HPeV-1 internalization and/or replication cycle. We demonstrate by antibody blocking assay, immunofluorescence microscopy and RT-qPCR that HPeV-1 internalizes and replicates in cell lines that express αVβ1 integrin but not αVβ3 or αVβ6 integrins. To further study the role of β1 integrin, we used a mouse cell line, GE11-KO, which is deficient in β1 expression, and its derivate GE11-β1 in which human integrin β1 subunit is overexpressed. HPeV-1 (Harris strain) and three clinical HPeV-1 isolates did not internalize into GE11-KO whereas GE11-β1 supported the internalization process. An integrin β1-activating antibody, TS2/16, enhanced HPeV-1 infectivity, but infection occurred in the absence of visible receptor clustering. HPeV-1 also co-localized with β1 integrin on the cell surface, and HPeV-1 and β1 integrin co-endocytosed into the cells. In conclusion, our results demonstrate that in some cell lines the cellular entry of HPeV-1 is primarily mediated by the active form of αVβ1 integrin without visible receptor clustering.

Therapeutic Use of Native and Recombinant Enteroviruses

Research on human enteroviruses has resulted in the identification of more than 100 enterovirus types, which use more than 10 protein receptors and/or attachment factors required in cell binding and initiation of the replication cycle. Many of these “viral” receptors are overexpressed in cancer cells. Receptor binding and the ability to replicate in specific target cells define the tropism and pathogenesis of enterovirus types, because cellular infection often results in cytolytic response, i.e., disruption of the cells. Viral tropism and cytolytic properties thus make native enteroviruses prime candidates for oncolytic virotherapy. Copy DNA cloning and modification of enterovirus genomes have resulted in the generation of enterovirus vectors with properties that are useful in therapy or in vaccine trials where foreign antigenic epitopes are expressed from or on the surface of the vector virus. The small genome size and compact particle structure, however, set limits to enterovirus genome modifications. This review focuses on the therapeutic use of native and recombinant enteroviruses and the methods that have been applied to modify enterovirus genomes for therapy.

Detection and monitoring of human bocavirus 1 infection by a new rapid antigen test

Clinically relevant diagnosis of human bocavirus 1 (HBoV1) is challenging, as the virus is frequently detected in asymptomatic patients, and cofindings with other respiratory viruses are common. The clinical value of current diagnostic methods, such as PCR, is therefore low, and alternative diagnostic strategies are needed. We describe for the first time the use of an antigen detection assay for the rapid identification of HBoV1 in a paediatric patient with respiratory tract infection symptoms. We estimate the duration of active HBoV1 infection to be 6 days.

Role of Heparan Sulfate in Cellular Infection of Integrin-Binding Coxsackievirus A9 and Human Parechovirus 1 Isolates

Heparan sulfate/heparin class of proteoglycans (HSPG) have been shown to function in cellular attachment and infection of numerous viruses including picornaviruses. Coxsackievirus A9 (CV-A9) and human parechovirus 1 (HPeV-1) are integrin-binding members in the family Picornaviridae. CV-A9 Griggs and HPeV-1 Harris (prototype) strains have been reported not to bind to heparin, but it was recently shown that some CV-A9 isolates interact with heparin in vitro via VP1 protein with a specific T132R/K mutation. We found that the infectivity of both CV-A9 Griggs and HPeV-1 Harris was reduced by sodium chlorate and heparinase suggestive of HSPG interactions. We analyzed the T132 site in fifty-four (54) CV-A9 clinical isolates and found that only one of them possessed T132/R mutation while the other nine (9) had T132K. We then treated CV-A9 Griggs and HPeV-1 Harris and eight CV-A9 and six HPeV-1 clinical isolates with heparin and protamine. Although infectivity of Griggs strain was slightly reduced (by 25%), heparin treatment did not affect the infectivity of the CV-A9 isolates that do not possess the T132R/K mutation, which is in line with the previous findings. Some of the HPeV-1 isolates were also affected by heparin treatment, which suggested that there may be a specific heparin binding site in HPeV-1. In contrast, protamine (a specific inhibitor of heparin) completely inhibited the infection of both prototypes and clinical CV-A9 and HPeV-1 isolates. We conclude that T132R/K mutation has a role in heparin binding of CV-A9, but we also show data, which suggest that there are other HSPG binding sites in CV-A9. In all, we suggest that HSPGs play a general role in both CV-A9 and HPeV-1 infections.

Generation and characterization of a single-chain anti-EphA2 antibody

Recombinant antibody phage library technology provides multiple advantages, including that human antibodies can be generated against proteins that are highly conserved between species. We used this technology to isolate and characterize an anti-EphA2 single-chain antibody. We show that the antibody binds the antigen with 1:1 stoichiometry and has high specificity for EphA2. The crystal structure of the complex reveals that the antibody targets the same receptor surface cavity as the ephrin ligand. Specifically, a lengthy CDR-H3 loop protrudes deep into the ligand-binding cavity, with several hydrophobic residues at its tip forming an anchor-like structure buried within the hydrophobic Eph pocket, in a way similar to the ephrin receptor-binding loop in the Eph/ephrin structures. Consequently, the antibody blocks ephrin binding to EphA2. Furthermore, it induces apoptosis and reduces cell proliferation in lymphoma cells lines. Since Ephs are important mediators of tumorigenesis, such antibodies could have applications both in research and therapy.

Elicitation of T-cell responses by structural and non-structural proteins of coxsackievirus B4

Coxsackievirus B4 (CV-B4) belongs to the genus Enterovirus within the family Picornaviridae. To investigate target proteins recognized by T-cells in human enterovirus B infections, virus-encoded structural [VP0 (VP4 and VP2), VP1, VP3] and non-structural (2A, 2B, 2C, 3C and 3D) proteins were expressed and purified in Escherichia coli. Peripheral blood of 19 healthy adult donors was used to create enterovirus-specific T-cell lines by repeated stimulation with CV-B4 cell lysate antigen. T-cell lines responded in individual patterns, and responses to all purified proteins were observed. The most often recognized enteroviral protein was VP0, which is the fusion between the most conserved structural proteins, VP4 and VP2. T-cell responses to VP0 were detected in 15 of the 19 (79 %) donor lines. Non-structural 2C protein was recognized in 11 of the 19 (58 %) lines, and 11 of the 19 (58 %) lines also had a response to 3D protein. Furthermore, responses to other non-structural proteins (2A, 2B and 3C) were also detected. T-cell responses did not correlate clearly to the individual HLA-DR-DQ phenotype or the history of past coxsackie B virus infections of the donors.

High-level expression of a full-length Eph receptor

Eph receptors are the largest family of Receptor Tyrosine Kinases containing a single membrane-spanning segment. They are involved in a various developmental and cell-cell communication events. Although there is extensive structural information available on both the extra- and intracellular regions of Eph's in isolation, no structures are available for the entire receptor. To facilitate structural studies on functionally relevant Eph/ephrin complexes, we have developed an expression system for producing the full-length human EphA2 receptor. We successfully expressed milligram amounts of the receptor using baculovirus-based vector and insect cells. We were also able to extract the protein from the cell membranes and purify it to near homogeneity in two simple steps. The purified receptor was shown to retain its biological activity in terms of both binding to its functional ligands and being able to auto-phosphorylate the key tyrosine residues of the cytoplasmic kinase domain.

Status and prospects of plant virus control through interference with vector transmission

Most plant viruses rely on vector organisms for their plant-to-plant spread. Although there are many different natural vectors, few plant virus-vector systems have been well studied. This review describes our current understanding of virus transmission by aphids, thrips, whiteflies, leafhoppers, planthoppers, treehoppers, mites, nematodes, and zoosporic endoparasites. Strategies for control of vectors by host resistance, chemicals, and integrated pest management are reviewed. Many gaps in the knowledge of the transmission mechanisms and a lack of available host resistance to vectors are evident. Advances in genome sequencing and molecular technologies will help to address these problems and will allow innovative control methods through interference with vector transmission. Improved knowledge of factors affecting pest and disease spread in different ecosystems for predictive modeling is also needed. Innovative control measures are urgently required because of the increased risks from vector-borne infections that arise from environmental change.

Endocytosis of integrin-binding human picornaviruses

Picornaviruses that infect humans form one of the largest virus groups with almost three hundred virus types. They include significant enteroviral pathogens such as rhino-, polio-, echo-, and coxsackieviruses and human parechoviruses that cause wide range of disease symptoms. Despite the economic importance of picornaviruses, there are no antivirals. More than ten cellular receptors are known to participate in picornavirus infection, but experimental evidence of their role in cellular infection has been shown for only about twenty picornavirus types. Three enterovirus types and one parechovirus have experimentally been shown to bind and use integrin receptors in cellular infection. These include coxsackievirus A9 (CV-A9), echovirus 9, and human parechovirus 1 that are among the most common and epidemic human picornaviruses and bind to αV-integrins via RGD motif that resides on virus capsid. In contrast, echovirus 1 (E-1) has no RGD and uses integrin α2β1 as cellular receptor. Endocytosis of CV-A9 has recently been shown to occur via a novel Arf6- and dynamin-dependent pathways, while, contrary to collagen binding, E-1 binds inactive β1 integrin and enters via macropinocytosis. In this paper, we review what is known about receptors and endocytosis of integrin-binding human picornaviruses.

Biological control of wood decay against fungal infection

Wood (timber) is an important raw material for various purposes, and having biological composition it is susceptible to deterioration by various agents. The history of wood protection by impregnation with synthetic chemicals is almost two hundred years old. However, the ever-increasing public concern and the new environmental regulations on the use of chemicals have created the need for the development and the use of alternative methods for wood protection. Biological wood protection by antagonistic microbes alone or in combination with (bio)chemicals, is one of the most promising ways for the environmentally sound wood protection. The most effective biocontrol antagonists belong to genera Trichoderma, Gliocladium, Bacillus, Pseudomonas and Streptomyces. They compete for an ecological niche by consuming available nutrients as well as by secreting a spectrum of biochemicals effective against various fungal pathogens. The biochemicals include cell wall-degrading enzymes, siderophores, chelating iron and a wide variety of volatile and non-volatile antibiotics. In this review, the nature and the function of the antagonistic microbes in wood protection are discussed.

A combined method for rescue of modified enteroviruses by mutagenic primers, long PCR and T7 RNA polymerase-driven in vivo transcription

The current methods for manipulation of enteroviral RNA genomes and production of modified virus particles include stepwise subcloning procedures and in vitro transcription and RNA transfection steps that are both time-consuming and inefficient. Several enteroviral cDNA clones with 5'-terminal T7 promoter and coxsackievirus A9 (CAV9) PCR product with the T7 promoter were transfected successfully into target cells expressing T7 RNA polymerase for the rescue of virus particles. This demonstrated the overall feasibility of the in vivo transcription method. Furthermore, a rapid method using high-fidelity DNA polymerase, Phusion™, for amplification and mutagenesis of CAV9 cDNA was generated. A long PCR method was employed together with mutagenic primers for direct introduction of a unique restriction enzyme site into the VP1-2A junction of the CAV9 cDNA clone during the PCR amplification process. Enhanced green fluorescent protein was subcloned to that site, and CAV9-eGFP cDNA was transfected to the target cells for in vivo transcription and successful rescue of CAV9-eGFP particles. The method allowed a straightforward mutagenesis and in vivo production of infectious enteroviral particles, and may be applicable routinely for rapid production of the modified picornaviruses over the use of the traditional subcloning protocols.

Coxsackievirus A6 and hand, foot, and mouth disease, Finland

During fall 2008, an outbreak of hand, foot, and mouth disease (HFMD) with onychomadesis (nail shedding) as a common feature occurred in Finland. We identified an unusual enterovirus type, coxsackievirus A6 (CVA6), as the causative agent. CVA6 infections may be emerging as a new and major cause of epidemic HFMD.

Integrin alphaVbeta6 is a high-affinity receptor for coxsackievirus A9

Coxsackievirus A9 (CAV9), a member of the genus Enterovirus in the family Picornaviridae, possesses an integrin-binding arginine-glycine-aspartic acid (RGD) motif in the C terminus of VP1 capsid protein. CAV9 has been shown to utilize integrins alphaVbeta3 and alphaVbeta6 as primary receptors for cell attachment. While CAV9 RGD-mutants (RGE and RGDdel) are capable of infecting rhabdomyosarcoma (RD) cell line, they grow very poorly in an epithelial lung carcinoma cell line (A549). In this study, the relationships between CAV9 infectivity in A549 and RD cells, receptor expression and integrin binding were analysed. A549 cells were shown to express both integrins alphaVbeta3 and alphaVbeta6, whereas alphaVbeta6 expression was not detected on the RD cells. Native CAV9 but not RGE and RGDdel mutants bound efficiently to immobilized alphaVbeta3 and alphaVbeta6. Adhesion of CAV9 but not RGE/RGDdel to A549 cells was also significantly higher than to RD cells. In contrast, no affinity or adhesion of bacterially produced VP1 proteins to the integrins or to the cells was detected. Function-blocking antibodies against alphaV-integrins blocked CAV9 but not CAV9-RGDdel infectivity, indicating that the viruses use different internalization routes; this may explain the differential infection kinetics of CAV9 and RGDdel. In an affinity assay, soluble alphaVbeta6, but not alphaVbeta3, bound to immobilized CAV9. Similarly, only soluble alphaVbeta6 blocked virus infectivity. These data suggest that CAV9 binding to alphaVbeta6 is a high-affinity interaction, which may indicate its importance in clinical infections; this remains to be determined.

Wide-range antifungal antagonism of Paenibacillus ehimensis IB-X-b and its dependence on chitinase and beta-1,3-glucanase production

Previously, we isolated a strain of Bacillus that had antifungal activity and produced lytic enzymes with fungicidal potential. In the present study, we identified the bacterium as Paenibacillus ehimensis and further explored its antifungal properties. In liquid co-cultivation assays, P. ehimensis IB-X-b decreased biomass production of several pathogenic fungi by 45%-75%. The inhibition was accompanied by degradation of fungal cell walls and alterations in hyphal morphology. Residual medium from cultures of P. ehimensis IB-X-b inhibited fungal growth, indicating the inhibitors were secreted into the medium. Of the 2 major lytic enzymes, chitinases were only induced by chitin-containing substrates, whereas beta-1,3-glucanase showed steady levels in all carbon sources. Both purified chitinase and beta-1,3-glucanase degraded cell walls of macerated fungal mycelia, whereas only the latter also degraded cell walls of intact mycelia. The results indicate synergism between the antifungal action mechanisms of these enzymes in which beta-1,3-glucanase is the initiator of the cell wall hydrolysis, whereas the degradation process is reinforced by chitinases. Paenibacillus ehimensis IB-X-b has pronounced antifungal activity with a wide range of fungi and has potential as a biological control agent against plant pathogenic fungi.

Clinical effects of rhinovirus infections

Rhinovirus is the major cause of common cold and frequently associates with acute wheezing, otitis media, sinusitis, and pneumonia. High prevalence of rhinovirus in hospitalized children and adults has been documented recently. We screened children > or =1 month of age, hospitalized for any infection, for the presence of rhinoviruses and recruited 24 families with > or =2 children for a 3-week follow-up study. Rhinovirus was detected in 46 (28%) of 163 hospitalizations by study children. Most rhinovirus-positive children (85%) had respiratory symptoms. During the follow-up, rhinoviruses were detected in virtually all children and in one-half of adults in families with a rhinovirus-positive index child, but commonly also in families with a rhinovirus-negative index child. Melting temperature and sequence analysis revealed the transmission routes of the viruses and showed that several virus types could circulate in the families simultaneously. Our studies corroborate the major contribution of rhinovirus to hospitalization of children, most often because of wheezing. Young children with respiratory symptoms are major spreaders of rhinovirus in family setting.

Structure of the mite-transmitted Blackcurrant reversion nepovirus using electron cryo-microscopy

Blackcurrant reversion nepovirus (BRV; genus Nepovirus) has a single-stranded, bipartite RNA genome surrounded by 60 copies of a single capsid protein (CP). BRV is the most important mite-transmitted viral pathogen of the Ribes species. It is the causal agent of blackcurrant reversion disease. We determined the structure of BRV to 1.7 nm resolution using electron cryo- microscopy (cryoEM) and image reconstruction. The reconstruction reveals a pseudo T=3 viral capsid similar to that of tobacco ringspot virus (TRSV). We modelled the BRV capsid protein to that of TRSV and fitted it into the cryoEM reconstruction. The fit indicated that the extended C-terminus of BRV-CP is located on the capsid surface and the N-terminus on the interior. We generated peptide antibodies to two putatively exposed C-terminal sequences and these reacted with the virus. Hence homology modelling may be useful for defining epitopes for antibody generation for diagnostic testing of BRV in commercial crops.

Rhinovirus transmission within families with children: incidence of symptomatic and asymptomatic infections

BACKGROUND

Rhinoviruses are the most common cause of respiratory tract infections, but the transmission in families has not been studied using sensitive and specific molecular detection methods.

METHODS

Children hospitalized for any infection were screened for rhinoviruses. Eight families with a rhinovirus-positive index child and 16 families with a rhinovirus-negative index child were monitored for 3 weeks for disease symptoms, and the presence and quantity of rhinoviruses in nasal swab samples were determined by quantitative reverse transcription-polymerase chain reaction. Rhinoviruses were further identified by melting temperature and partial sequence analysis.

RESULTS

The rates of rhinovirus infection were 1.00 cases per person among the 17 siblings and 0.50 cases per person among the 14 parents of rhinovirus-positive index patients; the rates were 0.54 cases per person among the 24 siblings and 0.23 cases per person among the 30 parents of rhinovirus-negative index patients. Symptomatic infections were associated with an age of <7 years but not with a high copy number of rhinovirus genomes. Virus typing revealed the transmission routes of the viruses and showed that several virus types could circulate in the families simultaneously.

CONCLUSIONS

Rhinoviruses are frequently transmitted from children to other family members. Most rhinovirus infections in young children are symptomatic, but secondary infections in adults are often asymptomatic. Multiple virus types circulate simultaneously in families.

Mutagenic analysis of potato virus X movement protein (TGBp1) and the coat protein (CP): in vitro TGBp1-CP binding and viral RNA translation activation

Previously, we have shown that encapsidated Potato virus X (PVX) RNA was non-translatable in vitro, but could be converted into a translatable form by binding of the PVX movement protein TGBp1 to one end of the virion or by coat protein (CP) phosphorylation. Here, a mutagenic analysis of PVX CP and TGBp1 was used to identify the regions involved in TGBp1-CP binding and translational activation of PVX RNA by TGBp1. It was found that the C-terminal (C-ter) 10/18 amino acids region was not essential for virus-like particle (VP) assembly from CP and RNA. However, the VPs assembled from the CP lacking C-ter 10/18 amino acids were incapable of TGBp1 binding and being translationally activated. It was suggested that the 10-amino-acid C-ter regions of protein subunits located at one end of a polar helical PVX particle contain a domain accessible to TGBp1 binding and PVX remodelling. The non-translatable particles assembled from the C-ter mutant CP could be converted into a translatable form by CP phosphorylation. The TGBp1-CP binding activity was preserved unless a conservative motif IV was removed from TGBp1. By contrast, TGBp1-dependent activation of PVX RNA translation was abolished by deletions of various NTPase/helicase conservative motifs and their combinations. The motif IV might be essential for TGBp1-CP binding, but insufficient for PVX RNA translation activation. The evidence to discriminate between these two events, i.e. TGBp1 binding to the CP-helix and TGBp1-dependent RNA translation activation, is discussed.

Microbial dextran-hydrolyzing enzymes: fundamentals and applications

Dextran is a chemically and physically complex polymer, breakdown of which is carried out by a variety of endo- and exodextranases. Enzymes in many groups can be classified as dextranases according to function: such enzymes include dextranhydrolases, glucodextranases, exoisomaltohydrolases, exoisomaltotriohydrases, and branched-dextran exo-1,2-alpha-glucosidases. Cycloisomalto-oligosaccharide glucanotransferase does not formally belong to the dextranases even though its side reaction produces hydrolyzed dextrans. A new classification system for glycosylhydrolases and glycosyltransferases, which is based on amino acid sequence similarities, divides the dextranases into five families. However, this classification is still incomplete since sequence information is missing for many of the enzymes that have been biochemically characterized as dextranases. Dextran-degrading enzymes have been isolated from a wide range of microorganisms. The major characteristics of these enzymes, the methods for analyzing their activities and biological roles, analysis of primary sequence data, and three-dimensional structures of dextranases have been dealt with in this review. Dextranases are promising for future use in various scientific and biotechnological applications.

Microbial dextran-hydrolyzing enzymes: fundamentals and applications

Dextran is a chemically and physically complex polymer, breakdown of which is carried out by a variety of endo- and exodextranases. Enzymes in many groups can be classified as dextranases according to function: such enzymes include dextranhydrolases, glucodextranases, exoisomaltohydrolases, exoisomaltotriohydrases, and branched-dextran exo-1,2-alpha-glucosidases. Cycloisomalto-oligosaccharide glucanotransferase does not formally belong to the dextranases even though its side reaction produces hydrolyzed dextrans. A new classification system for glycosylhydrolases and glycosyltransferases, which is based on amino acid sequence similarities, divides the dextranases into five families. However, this classification is still incomplete since sequence information is missing for many of the enzymes that have been biochemically characterized as dextranases. Dextran-degrading enzymes have been isolated from a wide range of microorganisms. The major characteristics of these enzymes, the methods for analyzing their activities and biological roles, analysis of primary sequence data, and three-dimensional structures of dextranases have been dealt with in this review. Dextranases are promising for future use in various scientific and biotechnological applications.

Black currant reversion virus, a mite-transmitted nepovirus

SUMMARY Taxonomy: Black currant reversion virus (BRV) is the first identified mite-transmitted member of the genus Nepovirus (family Comoviridae). A few systematic studies have been performed to compare virus isolates from different geographical locations. Physical properties: Purified preparations contain two closely sedimenting centrifugal components (B and M for RNA1 and RNA2, respectively) at varying ratios, and occasionally a T component (for satellite RNA). The BRV capsids have a diameter of 27 nm and they are putatively composed of 60 copies of a single species of capsid (coat) protein assembled in an icosahedral lattice. Diluted plant sap loses its infectivity within 1 day at 20 degrees C and in 4-8 days at 4 degrees C. Hosts: The natural host range of BRV is limited; it infects black currant (Ribes nigrum L.) and some related Ribes species. The transmission of the virus is by the eriophyid gall mite of black currant (Cecidophyopsis ribis). A number of herbaceous plants can be infected experimentally. BRV is the agent of black currant reversion disease (BRD), which is economically the most significant virus disease in Ribes species. BRV and BRD occur widely in locations where black currant is cultivated commercially.

Characteristics of RNA silencing in plants: similarities and differences across kingdoms

RNA silencing is a collective term that encompasses the sequence of events that leads to the targeted degradation of cellular mRNA and thus to the silencing of corresponding gene expression. RNA silencing is initiated after introduction into the host genome of a gene that is homologous to an endogenous gene. Transcription of the introduced gene results in the formation of double-stranded RNA (dsRNA) that is cut into smaller dsRNA species termed small interfering RNAs (siRNAs) by an RNaseIII-like enzyme called 'Dicer'. siRNAs associate with a protein complex termed the 'RNA-induced silencing complex' (RISC), which mediates the binding of one strand of siRNAs with mRNAs transcribed from the native 'target' gene. The binding of siRNAs with native gene mRNAs earmarks native gene mRNAs for destruction, resulting in gene silencing. In plants, RNA silencing appears to serve as a defence mechanism against viral pathogens and also to suppress the activity of virus-like mobile genetic elements. In an apparent response to RNA silencing, some plant viruses express suppressors of RNA silencing. RNA silencing also is directly implicated in the regulation of the function(s) of microRNAs, which are the key determinants in an additional cellular mechanism related to the translational repression of genes, the effect of which ultimately impinges on development. The high degree of sequence similarity that exists between genes involved in RNA silencing in widely different organisms underscores the conserved nature of many aspects of the RNA silencing mechanism. However, depending (for example) on the precise nature of the target gene involved, there also are significant differences in the silencing pathways that are engaged by various organisms.

Purification and properties of extracellular dextranase from a Bacillus sp

Bacterial strains in the genus Bacillus were isolated from natural soil samples and screened for production of extracellular dextranases (E.C.3.2.1.11). One strain, determined by 16sRNA analysis as Paenibacillus illinoisensis exhibiting stable dextranase activity, was chosen for further analysis, and the dextranase from it was purified 733-fold using salt and PEG precipitations, two-phase extraction and DEAE-Sepharose chromatography with a total yield of 19%. The purified enzyme had three isoforms, with molecular masses of 76, 89 and 110kDa and isoelectric points of 4.95, 4.2 and 4.0, respectively. The mixture of the three dextranase isoforms has a broad pH optimum around pH 6.8 and a temperature optimum at 50 degrees C. The N-terminal sequence (Ala-Ser-Thr-Gly-Lys) was identical between the isoforms. No sequence homology with the known dextranases in the protein databanks was found.

Dysfunctionality of a tobacco mosaic virus movement protein mutant mimicking threonine 104 phosphorylation

Replication of tobacco mosaic virus (TMV) is connected with endoplasmic reticulum (ER)-associated membranes at early stages of infection. This study reports that TMV movement protein (MP)-specific protein kinases (PKs) associated with the ER of tobacco were capable of phosphorylating Thr(104) in TMV MP. The MP-specific PKs with apparent molecular masses of about 45-50 kDa and 38 kDa were revealed by gel PK assays. Two types of mutations were introduced in TMV MP gene of wild-type TMV U1 genome to substitute Thr(104) by neutral Ala or by negatively charged Asp. Mutation of Thr(104) to Ala did not affect the size of necrotic lesions induced by the mutant virus in Nicotiana tabacum Xanthi nc. plants. Conversely, mutation of Thr to Asp mimicking Thr(104) phosphorylation strongly inhibited cell-to-cell movement. The possible role of Thr(104) phosphorylation in TMV MP function is discussed.

Simultaneous assessment of occupational exposures from multiple worker groups

The methods developed by Rappaport et al. [Ann. Occup. Hyg. 39 (1995) 469] and Lyles et al. [J. Agri. Bio. Environ. Stat. 2 (1997a) 64; Ann. Occup. Hyg. 41 (1997b) 63]) for assessing workplace exposures on a group-by-group basis are extended to allow for the simultaneous assessment of data from multiple worker groups within the same industry. These extended methods allow models to be fit simultaneously to data on all groups in a study, even when some of the groups might not contribute adequate information to be modeled separately. We assume that the exposures are log-normally distributed, and that they can be adequately modeled by a mixed effects regression model with parameters for exposure levels and for between- and within-worker variance components. Simultaneously analyzing data from multiple groups is only advantageous when at least one of these variance components can be assumed to be homogeneous across the groups. Here, we advocate testing an assumption of homogeneous within-worker variance components, sigma(2)(w,h), using a likelihood ratio test to choose between a full model (distinct sigma(2)(w,h) for each group) and a reduced model (common sigma(2)(w) across groups). We then develop a procedure, which is conditional on the results of the likelihood ratio test, for testing whether or not each group of workers is overexposed to the contaminant of interest. This modeling and testing procedure was applied to 39 different data sets, each containing data for multiple groups, from a wide variety of industries. For these data, the testing procedure generally resulted in the same conclusion regarding overexposure under both models, even in those data sets where the within-worker variance components appeared to be quite heterogeneous. We also conducted a small simulation study to estimate the significance level of the proposed testing procedure, and found that the significance levels tended to be adequately close to the specified nominal level when a likelihood ratio test with significance level of at least 0.01 was used as a preliminary test. Additionally, we make specific recommendations for designing studies and suggest a method for determining whether engineering and administrative controls or individual-level interventions would be of most benefit to an overexposed group of workers.

The use of a task-based exposure assessment model (T-BEAM) for assessment of metal fume exposures during welding and thermal cutting

Elevated disease rates have been documented among construction workers for cancer, pneumonoconiosis, asbestosis, and silicosis. However, methodologies for exposure assessment in construction are not well described in the U.S. literature. Working through a cooperative agreement with the National Institute for Occupational Safety and Health (NIOSH), the Center to Protect Workers' Rights--a research arm of the Building and Construction Trades Department, AFL-CIO--has developed and used a "Task-Based Exposure Assessment Model (T-BEAM)" for construction. The characteristic elements of T-BEAM are: (1) an emphasis on the identification, implementation, and evaluation of engineering and work practice controls; and (2) use of experienced, specially trained construction workers (construction safety and health specialists) in the exposure assessment process. A task-based approach was used because tasks, or specialized skills, form the single greatest thread of continuity in the dynamic environment of construction. Workers in the construction industry come from several crafts and are typically employed by a large number of contractors throughout their career. Project types (e.g., residential or industrial rehabilitation) are also highly variable and present unique health risks. Finally, because construction involves building, renovating, or dismantling physical surroundings, the work site is constantly changing. Between 1995 and 1996, T-BEAM was applied to the collection of approximately 200 personal exposure measurements associated with "hot work tasks"--welding and thermal cutting. Data were collected with the assistance of specially trained, journeyman ironworkers, pipe fitters, and boilermakers on nine construction sites located throughout the United States. Portable local exhaust ventilation was provided to participating contractors with the intent of measuring its impact on exposure. Results indicate that data collected in a standardized, systematic fashion from multiple work sites can be used to characterize exposures among sampled trades. Comparison of results to American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) demonstrate a significant health hazard among sampled trades posed by welding and thermal cutting fume, manganese, nickel, and chromium VI. Direct estimates of the probability of exceeding the ACGIH TLV for respirable particulate suggests that boilermakers (100%) and ironworkers (71%) are at greatest risk. Other task variables evaluated with respect to exposure include task, whether work was performed indoors or outdoors, intermittency of work, and use of ventilation. Use of local or mechanical ventilation reduced mean exposures to fumes significantly.

Application of mixed models to assess exposures monitored by construction workers during hot processes

Particulate exposures were assessed among construction workers engaged in hot processes in four jobs (boilermakers, ironworkers, pipefitters and welder-fitters) at nine sites in the U.S. After being trained by occupational hygienists, the workers obtained shift-long personal samples at each site for total particulates (TP). Selected samples were also assayed for manganese (Mn), nickel (Ni), and chromium (Cr). Workers provided information about process- and task-related covariates that were present on the days of monitoring. Data were investigated with mixed-model regression analyses that designated the jobs and covariates as fixed effects and the worker and error terms as random effects. Results indicated that the within-worker variance components, but not the between-worker variance components, could be pooled among jobs. Mean air levels for a given agent varied by roughly six to 100 fold among the jobs, with boilermakers and ironworkers experiencing much higher levels of TP and Mn than pipefitters and welder-fitters. Limited data also suggested that welder-fitters were exposed to greater levels of Ni and Cr than pipefitters. Sufficient sample sizes were available to evaluate the effects of covariates upon exposures to TP and Mn. As expected, processes involving more than 50% hot work led to substantially higher levels of TP and Mn than those involving shorter durations of hot work. Local-exhaust or mechanical ventilation reduced exposure to TP (but not Mn) by as much as 44%, and shielded or manual arc welding increased exposure to Mn (but not TP) by about 80%. Parameters estimated with these mixed models were used to calculate probabilities that workers were exposed at levels above U.S. occupational exposure limits (OELs). Regarding TP and Mn, these calculations suggested that 26-95% of exposures to boilermakers and pipefitters and 2-13% of exposures to pipefitters and welder-fitters exceeded the current Threshold Limit Values. Among welder-fitters, limited data also pointed to probabilities of 2-50% for exceeding particular OELs for Ni and Cr. Using the significance of the estimated random-worker effects as a gauge for the uniformity of exposure within a job, administrative or engineering changes appear appropriate for reducing exposures to boilermakers and ironworkers, while individual personal environments should be investigated for pipefitters and welder-fitters.

Replication in the phloem is not necessary for efficient vascular transport of tobacco mosaic tobamovirus

Plant viruses move systemically from one leaf to another via phloem. However, the viral functions needed for systemic movement are not fully elucidated. An experimental system was designed to study the effects of low temperature on the vascular transport of the tobacco mosaic tobamovirus (TMV). Vascular transport of TMV from lower inoculated leaves to upper non-inoculated leaves via a stem segment kept at low temperature (4 degrees C) was not affected. On the other hand, several experiments were performed on tobacco leaves to demonstrate that virus replication did not occur at the same temperature. The data suggest that replication of TMV in the phloem of wild-type tobacco plants is not necessary for the vascular transport of TMV, and that the virus moves with photoassimilates as suggested previously.

Selection of single-chain variable fragment antibodies to black currant reversion associated virus from a synthetic phage display library

ABSTRACT Single-chain variable fragment (scFv) antibodies that bind to black currant reversion associated virus (BRAV) were obtained from a synthetic phage display antibody gene library without recourse to animal immunizations. Several different BRAV-specific phage scFv were obtained quickly, after only three rounds of selection against immobilized virus antigen. The phage scFv gave enzyme-linked immunosorbent assay (ELISA) absorbance values that were greater than seven times the control healthy plant extracts. In contrast, comparative tests using a rabbit antiserum failed, because unacceptably high background values were obtained with healthy plant extracts. Two of the scFv were subcloned into the pDAP2 vector for the rapid and efficient production of scFv-alkaline phosphatase fusion proteins. Functional fusion proteins were obtained after expression in Escherichia coli, and preparations from periplasmic extracts detected BRAV in ELISA. The results demonstrate that antibody fragments obtained from a synthetic phage display library are useful research tools, and they proved to be a viable practical alternative when traditional antisera failed to detect BRAV, a weak immunogen. Furthermore, the genetic fusion of antibody fragments to alkaline phosphatase obviates the need for further chemical coupling procedures, and the fusion proteins can be obtained cheaply.

Characterization of the coat protein gene of mite-transmitted blackcurrant reversion associated nepovirus

The nucleotide sequence of the 3' terminal 3105 nucleotides (nt) of RNA2 of blackcurrant reversion associated virus (BRAV), the first mite-transmitted member of the nepovirus group, has been determined. The sequence contains an open reading frame of 1744 nt in the virus-sense strand, a 3' untranslated region of 1360 nt and a 3' poly(A) tail. Analysis of the amino-terminal residues of purified coat protein (CP) suggests that the CP gene is located between nts 1361 and 2959 (from the 3' terminus) in the RNA2, and that Asp/Ser is the proteolytic cleavage site of CP in the RNA2 encoded polyprotein. The predicted translation product from the CP gene is a polypeptide of 533 amino acids with a calculated Mr of 57 561. The amino acid sequence of BRAV CP showed highest similarity to blueberry leaf mottle virus (BLMV), and tomato ringspot virus (ToRSV), two members of the proposed sub-group three of nepoviruses possessing large RNA2 components. Nucleic and amino acid sequence comparisons between BRAV CP and the CPs of other nepoviruses indicate that specific conserved nepovirus CP domains occur in the BRAV CP thus confirming that BRAV is a member of the subgroup three of nepoviruses. reserved.

Purification and properties of a new virus from black currant, its affinities with nepoviruses, and its close association with black currant reversion disease

ABSTRACT Black currant reversion is a virus-like disease whose causal agent has not been identified. In rooted cuttings of a black currant plant affected with the severe form of the disease, pronounced chlorotic line patterns and ringspots developed in newly emerging leaves. From such symptom-bearing leaves, a virus was mechanically transmitted with difficulty to Chenopodium quinoa and, from this host, to other herbaceous test plants. The virus was purified and partially characterized, and the purified viri-ons were used for antiserum production. Virus particles were isometric, approximately 27 nm in diameter, and sedimented as two nucleoprotein components. They contained a protein species with a molecular mass of 55 kDa, which was readily degraded into a 54-kDa protein and two major RNA components of about 6,700 and 7,700 nucleotides (nt), each with a poly(A) tail. Most of these properties are shared by nepoviruses, but the virus was serologically unrelated to 14 nepoviruses or putative nepovi-ruses tested. However, the deduced sequence of 1,260 nt at the 3' end of one of the viral RNA species was distinct from any known viral sequence, except that it contained short regions of homology to the 3' terminal sequences of RNAs of seven other nepoviruses and two comovi-ruses. To detect this virus in Ribes plants, primers were designed from the known sequence to amplify a 210-nt region of the cDNA of the virus RNA using an immunocapture reverse transcriptase polymerase chain reaction (IC-RT-PCR) protocol. Using this assay for the virus, we associated its presence with two recognized forms of black currant reversion disease occurring in Finland, Scotland, or New Zealand. We also detected the virus in vector gall mites from reverted plants and in black currant plants on which such vector mites had fed. However, the virus was not detected by IC-RT-PCR in known healthy Ribes plants; in Ribes plants free from reversion, but affected by three other distinct virus-like diseases of Ribes; or in plants infected with arabis mosaic, strawberry latent ringspot, or raspberry ringspot nepoviruses. These data suggest that this virus may be the causal agent of reversion disease, and it is tentatively called black currant reversion associated virus.

Ergonomics and construction: a review of potential hazards in new construction

This article reviews potential ergonomic hazards in new construction work, summarizing findings from published literature and from a 15-month investigation of health hazards on a new construction site in suburban Washington, D.C. The review is structured to follow the sequence of events in the construction process. Ergonomic solutions are included where they have been developed. Highway work and renovation and demolition of existing structures, the segments of construction that are growing, are not discussed here. However, many of the same problems and principles apply to other sectors of construction.