Publications

The Pirbright Institute publication directory contains details of selected publications written by our researchers.

There were a total of 2599 results for your search.

Abstract

Autophagy is a cellular response to starvation which generates autophagosomes to carry cellular organelles and long-lived proteins to lysosomes for degradation. Degradation through autophagy can provide an innate defense against virus infection, or conversely autophagosomes can promote infection by facilitating assembly of replicase proteins. We demonstrate that the avian coronavirus, infectious bronchitis virus (IBV), activates autophagy. A screen of individual IBV nonstructural proteins (nsps) showed that autophagy was activated by IBV nsp6. This property was shared with nsp6 of mammalian coronaviruses mouse hepatitis virus, and severe acute respiratory syndrome virus, and the equivalent nsp5-7 of the arterivirus porcine reproductive and respiratory syndrome virus. These multiple-spanning transmembrane proteins located to the endoplasmic reticulum (ER) where they generated Atg5 and LC3II-positive vesicles, and vesicle formation was dependent on Atg5 and class III PI3 kinase. The vesicles recruited double-FYVE-domain containing protein (DFCP) indicating localized concentration of phosphatidylinositol 3 phosphate, and therefore shared many features with omegasomes formed from the ER in response to starvation. Omegasomes induced by viral nsp6 matured into autophagosomes that delivered LC3 to lysosomes and therefore recruited and recycled the proteins needed for autophagosome nucleation, expansion, cellular trafficking and delivery of cargo to lysosomes. The coronavirus nsp6 proteins activated omegasome and autophagosome formation independently of starvation, but activation did not involve direct inhibition of mTOR signaling, activation of sirtuin 1 or induction of ER stress.

Abstract

Foot-and-mouth disease vaccine potency testing involving live virus challenge can be problematical in pigs. Alternative methods of assessing vaccine efficacy are therefore desirable. Here we investigate the link between IL-6 in blood at time of challenge and protection against challenge by carrying out statistical analyses utilising data from six separate potency tests performed in swine with the aim of assessing whether IL-6 could be exploited as an additional parameter for confirming vaccine efficacy in pigs. These analyses confirmed that systemic IL-6 levels increased when the administered vaccine dose increased and that the odds of protection against challenge increased as IL-6 levels increased. The link between increased protection and increased antibody was reaffirmed and a significant link between IL-6 levels and antibody levels was shown. We therefore conclude that quantifying the levels of IL-6 in serum could provide additional means of qualifying whether a vaccine will afford clinical protection or not in pigs, in the absence of an actual challenge, and thus offer the possibility of improved vaccine potency testing in pigs both in terms of animal welfare as well as cost.
Crafford J E, Guthrie A J, Van Vurren M, Mertens P P C, Burroughs J N, Howell P G, Batten C A, Hamblin C (2011)

A competitive ELISA for the detection of group-specific antibody to equine encephalosis virus

Journal of Virological Methods 174 (1-2), 60-64

Abstract

A polyclonal antibody-based, group-specific, competitive ELISA (C-ELISA) for the detection of antibodies to equine encephalosis virus (EEV) was developed. The assay measures the competition between a specific guinea pig antiserum and a test serum, for a pre-titrated EEV antigen. The C-ELISA detected antibodies to the seven known EEV serotypes. Reference antisera raised against other arboviruses did not cross react with EEV antigen. Negative sera from horses in the United Kingdom were used to establish the baseline for a negative population. Negative and positive populations of South African horses, selected on the basis of virus neutralisation were assayed subsequently. Optimal test parameters, where sensitivity congruent to specificity congruent to 100%, were calculated by two-graph receiver operator characteristic (TG-ROC) analysis to be at a cut-off value of 29.5% inhibition. Results show the EEV C-ELISA described to be sensitive, specific and reliable. Used in conjunction with ELISAs available for African horse sickness virus (AHSV), differential serological diagnosis between EEV and AHSV can be achieved.

Abstract

Targeting dendritic cells (DC) is key to driving effective immune responses. Lymphatic cannulation provides access to the heterogeneous populations of DC draining peripheral sites in rodents and ruminants. Afferent lymph DEC-205(+) CD11c(+) SIRP alpha(+) DC were preferentially infected ex vivo with three vaccine viral vectors: recombinant human replication-defective human adenovirus 5 (rhuAdV5), recombinant modified vaccinia virus Ankara (rMVA), and recombinant fowlpox virus (rFPV), all expressing green fluorescent protein (GFP). The rhuAdV5-infected cells remained viable, and peak GFP expression was observed 16 to 24 h posttransduction. Increasing the incubation period of DC with rhuAdV5 enhanced GFP expression. In contrast, DC infected with rMVA-GFP or rFPV-GFP became rapidly apoptotic and GFP expression peaked at 6 h postinfection. Delivery of foot-and-mouth disease virus (FMDV) A(22) antigen to DC by rhuAdV5-FMDV-A(22) ex vivo resulted in significantly greater CD4(+) T cell proliferation than did delivery by rFPV-FMDV-A(22). Delivery of rhuAdV5-GFP in oil adjuvant in vivo, to enhance DC-vector contact, resulted in increased GFP expression in migrating DC compared to that with vector alone. Similarly, CD4(+) T cell responses were significantly enhanced when using rhuAdV5-FMDV-A(22) in adjuvant. Therefore, the interaction between viral vectors and afferent lymph DC ex vivo can predict the outcome of in vivo immunization and provide a means of rapidly assessing the effects of vector modification.

Abstract

Bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) are related orbiviruses, transmitted between their ruminant hosts primarily by certain haematophagous midge vectors (Culicoides spp.). The larger of the BTV outer-capsid proteins, ‘VP2’, can be cleaved by proteases (including trypsin or chymotrypsin), forming infectious subviral particles (ISVP) which have enhanced infectivity for adult Culicoides, or KC cells (a cell-line derived from C. sonorensis). We demonstrate that VP2 present on purified virus particles from 3 different BTV strains can also be cleaved by treatment with saliva from adult Culicoides. The saliva proteins from C. sonorensis (a competent BTV vector), cleaved BTV-VP2 more efficiently than those from C. nubeculosus (a less competent / non-vector species). Electrophoresis and mass spectrometry identified a trypsin-like protease in C. sonorensis saliva, which was significantly reduced or absent from C. nubeculosus saliva. Incubating purified BTV-1 with C. sonorensis saliva proteins also increased their infectivity for KC cells ~10 fold, while infectivity for BHK cells was reduced by 2–6 fold. Treatment of an ‘eastern’ strain of EHDV-2 with saliva proteins of either C. sonorensis or C. nubeculosus cleaved VP2, but a ‘western’ strain of EHDV-2 remained unmodified. These results indicate that temperature, strain of virus and protein composition of Culicoides saliva (particularly its protease content which is dependent upon vector species), can all play a significant role in the efficiency of VP2 cleavage, influencing virus infectivity. Saliva of several other arthropod species has previously been shown to increase transmission, infectivity and virulence of certain arboviruses, by modulating and/or suppressing the mammalian immune response. The findings presented here, however, demonstrate a novel mechanism by which proteases in Culicoides saliva can also directly modify the orbivirus particle structure, leading to increased infectivity specifically for Culicoides cells and, in turn, efficiency of transmission to the insect vector.
de Valdez M R W, Nimmo D, Betz J, Gong H F, James A A, Alphey L, Black W C (2011)

Genetic elimination of dengue vector mosquitoes

Proceedings of the National Academy of Sciences of the United States of America 108 (12), 4772-4775

Abstract

An approach based on mosquitoes carrying a conditional dominant lethal gene (release of insects carrying a dominant lethal, RIDL) is being developed to control the transmission of dengue viruses by vector population suppression. A transgenic strain, designated OX3604C, of the major dengue vector, Aedes aegypti, was engineered to have a repressible female-specific flightless phenotype. This strain circumvents the need for radiation-induced sterilization, allows genetic sexing resulting in male-only releases, and permits the release of eggs instead of adult mosquitoes. OX3604C males introduced weekly into large laboratory cages containing stable target mosquito populations at initial ratios of 8.5-10:1 OX3604C:target eliminated the populations within 10-20 weeks. These data support the further testing of this strain in contained or confined field trials to evaluate mating competitiveness and environmental and other effects. Successful completion of the field trials should facilitate incorporation of this approach into area-wide dengue control or elimination efforts as a component of an integrated vector management strategy.
Di Nardo A, Knowles N J, Paton D J (2011)

Combining livestock trade patterns with phylogenetics to help understand the spread of foot and mouth disease in sub-Saharan Africa, the Middle East and Southeast Asia

Revue Scientifique et Technique 30 (1), 63-85

Abstract

International trade in animals and their products is recognised as a primary determinant of the global epidemiology of transboundary diseases such as foot and mouth disease (FMD). As well as causing serious production losses, FMD is highly contagious, being transmitted through multiple routes and hosts, which makes it one of the most important diseases affecting trade in livestock. Its occurrence has dramatic consequences for the agricultural economy of a normally disease-free country, as well as for the livelihoods and income generation of developing countries where the disease continues to be endemic. In the dynamic of FMD virus (FMDV) dispersal across the globe, phylogenetic inference from molecular sequences of isolated viruses makes a significant contribution to investigating the evolutionary and spatial pathways underlying the source of FMD epidemics. Matching data on livestock movement with molecular epidemiology can enhance our fundamental understanding when reconstructing the spread of the virus between geographical regions, which is essential for the development of FMD control strategies worldwide. This paper reviews the global situation of FMD in the last ten years, combining phylogenetic insights with information on livestock production systems and international trade to analyse the epidemiological dynamics of FMD and the sources of FMDV introductions at a regional level in sub-Saharan Africa, the Middle East and Southeast Asia.

Abstract

Massively parallel sequencing of transposon-flanking regions assigned the genotype and fitness score to 91% of Escherichia coli O157:H7 mutants previously screened in cattle by signature-tagged mutagenesis (STM). The method obviates the limitations of STM and markedly extended the functional annotation of the prototype E. coli O157:H7 genome without further animal use.

Abstract

A sandwich ELISA using recombinant integrin ?v?6 as a capture ligand and serotype-specific monoclonal antibodies (Mabs) as detecting reagents has been compared with a polyclonal antibody based ELISA (using type-specific rabbit antibodies as capture and guinea pig antibodies as detectors), which is employed routinely at the FAO World Reference Laboratory for Foot-and-Mouth Disease (FMD), for the identification and serotyping of FMD virus (FMDV). The study used cell culture grown antigens (1351 FMDV positive) derived from suspected cases of vesicular disease collected from 86 countries between 1924 and 2011, those positive for the other vesicular diseases of swine vesicular disease (n = 25) and vesicular stomatitis (n = 45) and negative samples collected from uninfected cell cultures (n = 36). The diagnostic sensitivity of the assays was similar at 98.1% (polyclonal ELISA) compared to 97.9% (integrin/Mab ELISA) but the serotypic-specificity of the latter was vastly superior (96%) to that of the former (61.5%). Reactions with the viruses of swine vesicular disease and vesicular stomatitis, which produce clinically indistinguishable syndromes in pigs and cattle, did not occur. The integrin/Mab ELISA recognized FMDV strains of wide antigenic and molecular diversity of all seven serotypes and although some FMDV isolates were not detected, the greater specificity of the assay, while retaining test sensitivity comparable to the conventional assay, warrants its consideration for adoption for routine diagnostic use.

Abstract

Salmonella-infected poultry products are a major source of human Salmonella infection. The prophylactic use of antimicrobials in poultry production was recently banned in the EU, increasing the need for alternative methods to control Salmonella infections in poultry flocks. Genetic selection of chickens more resistant to Salmonella colonization provides an attractive means of sustainably controlling the pathogen in commercial poultry flocks and its subsequent entry into the food chain. Analysis of different inbred chickens has shown that individual lines are consistently either susceptible or resistant to the many serovars of Salmonella that have been tested. In this study, two inbred chicken lines with differential susceptibility to Salmonella colonization (61(R) and N(S)) were used in a backcross experimental design. Unlike previous studies that used a candidate gene approach or low-density genome-wide screens, we have exploited a high-density marker set of 1255 SNPs covering the whole genome to identify quantitative trait loci (QTL). Analysis of log-transformed caecal bacterial levels between the parental lines revealed a significant difference at 1, 2, 3 and 4 days post-infection (P

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