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

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Wilson A J, Ribeiro R, Boinas F (2013)

Use of a Bayesian network model to identify factors associated with the presence of the tick Ornithodoros erraticus on pig farms in southern Portugal

Preventive Veterinary Medicine 110 (1), 45-53
Publisher’s version: http://dx.doi.org/10.1016/j.prevetmed.2013.02.006

Abstract

The soft tick Ornithodoros erraticus occurs on pig farms in southern Portugal and Spain and transmits several important pathogens of humans and livestock. Its distribution is patchy and the determinants of its distribution are uncertain. Here, we use a Bayesian network model to explore possible associations between climate, farm management and the presence of O. erraticus. The resulting network confirms previous suggestions that the presence of O. erraticus is more likely in traditionally constructed pig housing, and indicates that carbon dioxide traps are highly effective for the detection of O. erraticus. Our approach also picked up several other intuitively reasonable relationships, including that traditional housing was more likely to be in poor condition and more likely to be out of use, and that buildings which were in use to house pigs were also less likely to be derelict. Neither temperature nor precipitation had any direct effect on the probability of the presence of O. erraticus, suggesting that the distribution of the species is primarily driven by farm management factors.
Xu L, Hurtle W, Rowland J M, Casteran K A, Bucko S M, Grau F R, Valdazo-Gonzalez B, Knowles N J, King D P, Beckham T R, McIntosh M T (2013)

Development of a universal RT-PCR for amplifying and sequencing the leader and capsid-coding region of foot-and-mouth disease virus

Journal of Virological Methods 189 (1), 70-76
Publisher’s version: http://dx.doi.org/10.1016/j.jviromet.2013.01.009

Abstract

Foot-and-mouth disease (FMD) is a highly infectious viral disease of cloven-hoofed animals with debilitating and devastating consequences for livestock industries throughout the world. Key antigenic determinants of the causative agent, FMD virus (FMDV), reside within the surface-exposed proteins of the viral capsid. Therefore, characterization of the sequence that encodes the capsid (P1) is important for tracking the emergence or spread of FMD and for selection and development of new vaccines. Reliable methods to generate sequence for this region are challenging due to the high inter-serotypic variability between different strains of FMDV. This study describes the development and optimization of a novel, robust and universal RT-PCR method that may be used to amplify and sequence a 3 kilobase (kb) fragment encompassing the leader proteinase (L) and capsid-coding portions (P1) of the FMDV genome. This new RT-PCR method was evaluated in two laboratories using RNA extracted from 134 clinical samples collected from different countries and representing a range of topotypes and lineages within each of the seven FMDV serotypes. Sequence analysis assisted in the reiterative design of primers that are suitable for routine sequencing of these RT-PCR fragments. Using this method, sequence analysis was undertaken for 49 FMD viruses collected from outbreaks in the field. This approach provides a robust tool that can be used for rapid antigenic characterization of FMDV and phylogenetic analyses and has utility for inclusion in laboratory response programs as an aid to vaccine matching or selection in the event of FMD outbreaks.
Yamazaki W, Mioulet V, Murray L, Madi M, Haga T, Misawa N, Horii Y, King D P (2013)

Development and evaluation of multiplex RT-LAMP assays for rapid and sensitive detection of foot-and-mouth disease virus

Journal of Virological Methods 192 (1-2), 18-24
Publisher’s version: http://dx.doi.org/10.1016/j.jviromet.2013.03.018

Abstract

This paper describes the evaluation of four novel real-time multiplex reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays for rapid and sensitive diagnosis of foot-and-mouth disease (FMD). In order to overcome the genetic diversity of FMD viruses (FMDV), these multiplex RT-LAMP assay pairs were established by combining four newly designed primer sets with two primer sets that had been previously published. Using a real-time turbidimeter to detect amplification products and a panel of 300 samples collected throughout the world over a 78-year period, the performance of the multiplex RTLAMP assays was compared with a FMDV-specific real-time RT-PCR assay. The most successful of the four multiplex RT-LAMP assays achieved a diagnostic sensitivity and specificity of 98.0% and 98.1%, and did not falsely detect FMDV in known negatives or samples containing swine vesicular disease virus, vesicular stomatitis virus or vesicular exanthema of swine virus. Furthermore, the analytical sensitivity of this multiplex RT-LAMP assay was at least as good as the individual component RT-LAMP tests. This is the first report of the development of a multiplex RT-LAMP to accommodate the high sequence variability encountered in RNA virus genomes and these results support the use of RT-LAMP as a cost-effective tool for simple diagnosis of FMD.
Wright C F, Knowles N J, Di Nardo A, Paton D J, Haydon D T, King D P (2013)

Reconstructing the origin and transmission dynamics of the 1967-68 foot-and-mouth disease epidemic in the United Kingdom

Infection Genetics and Evolution 20, 230-238
Publisher’s version: https://doi.org/10.1016/j.meegid.2013.09.009

Abstract

A large epidemic of foot-and-mouth disease (FMD) occurred in the United Kingdom (UK) over a seven month period in Northwest England from late 1967 to the summer of 1968. This was preceded by a number of smaller FMD outbreaks in the country, two in 1967, in Hampshire and Warwickshire and one in Northumberland during 1966. The causative agent of all four events was identified as FMD virus (FMDV) serotype O and the source of the large epidemic was attributed to infected bone marrow in lamb products imported from Argentina. However, the diagnostic tools available at the time were unable to entirely rule out connections with the earlier UK FMD outbreaks, as well as other potential sources from Europe. The aim of this study was to apply molecular sequencing to investigate the likely source of this epidemic using VP1 region and full genome (FG) sequences determined directly from clinical epithelium samples (n = 13) or cell culture isolates (n = 6), from this and contemporary outbreaks in the UK, Europe and South America. Analysis of the VP1 sequences provided evidence for at least three separate incursions of FMDV into the UK including one independent introduction that was responsible for the main 1967/68 epidemic. Analysis of FG sequences from the main 1967/68 outbreak (n = 10) revealed nucleotide substitutions at 94 genomic sites providing evidence for the linear accumulation of nucleotide substitutions (rate = 2.42 x 10(-5) nt substitutions/site/day). However, there were five samples where this linear relationship was absent, indicating evolutional dormancy of the virus, presumably outside a host. These results help define the evolutionary dynamics of FMDV during an epidemic and contribute to the knowledge and understanding from which to base future outbreak control strategies.

Iqbal M, Yaqub T, Mukhtar N, Shabbir M Z, McCauley J W (2013)

Infectivity and transmissibility of H9N2 avian influenza virus in chickens and wild terrestrial birds

Veterinary Research 44, e100
Publisher’s version: http://dx.doi.org/10.1186/1297-9716-44-100

Abstract

Genetic changes in avian influenza viruses influence their infectivity, virulence and transmission. Recently we identified a novel genotype of H9N2 viruses in widespread circulation in poultry in Pakistan that contained polymerases (PB2, PB1 and PA) and non-structural (NS) gene segments identical to highly pathogenic H7N3 viruses. Here, we investigated the potential of these viruses to cause disease and assessed the transmission capability of the virus within and between poultry and wild terrestrial avian species. Groups of broilers, layers, jungle fowl, quail, sparrows or crows were infected with a representative strain (A/chicken/UDL-01/08) of this H9N2 virus and then mixed with naive birds of the same breed or species, or different species to examine transmission. With the exception of crows, all directly inoculated and contact birds showed clinical signs, varying in severity with quail showing the most pronounced clinical signs. Virus shedding was detected in all infected birds, with quail showing the greatest levels of virus secretion, but only very low levels of virus were found in directly infected crow samples. Efficient virus intra-species transmission was observed within each group with the exception of crows in which no evidence of transmission was seen. Interspecies transmission was examined between chickens and sparrows and vice versa and efficient transmission was seen in either direction. These results highlight the ease of spread of this group of H9N2 viruses between domesticated poultry and sparrows and show that sparrows need to be considered as a high risk species for transmitting H9N2 viruses between premises.
Jabbar T K, Calvo-Pinilla E, Mateos F, Gubbins S, Bin-Tarif A, Bachanek-Bankowska K, Alpar O, Ortego J, Takamatsu H-H, Mertens P P C, Castillo-Olivares J (2013)

Protection of IFNAR (-/-) mice against bluetongue virus serotype 8, by heterologous (DNA/rMVA) and homologous (rMVA/rMVA) vaccination, expressing outer-capsid protein VP2

PLoS ONE 8 (4), e60574
Publisher’s version: http://dx.doi.org/10.1371/journal.pone.0060574

Abstract

The protective efficacy of recombinant vaccines expressing serotype 8 bluetongue virus (BTV-8) capsid proteins was tested in a mouse model. The recombinant vaccines comprised plasmid DNA or Modified Vaccinia Ankara viruses encoding BTV VP2, VP5 or VP7 proteins. These constructs were administered alone or in combination using either a homologous prime boost vaccination regime (rMVA/rMVA) or a heterologous vaccination regime (DNA/rMVA). The DNA/rMVA or rMVA/rMVA prime-boost were administered at a three week interval and all of the animals that received VP2 generated neutralising antibodies. The vaccinated and non-vaccinated-control mice were subsequently challenged with a lethal dose of BTV-8. Mice vaccinated with VP7 alone were not protected. However, mice vaccinated with DNA/rMVA or rMVA/rMVA expressing VP2, VP5 and VP7 or VP2 alone were all protected.
Jansen C A, de Geus E, van Haarlem D A, van de Haar P M, Londt B Z, Graham S P, Gobel T W, van Eden W, Brookes S M, Vervelde L (2013)

Differential lung NK cell responses in avian influenza virus infected chickens correlate with pathogenicity

Scientific Reports 3, e2478
Publisher’s version: http://dx.doi.org/10.1038/srep02478

Abstract

Infection of chickens with low pathogenicity avian influenza (LPAI) virus results in mild clinical signs while infection with highly pathogenic avian influenza (HPAI) viruses causes death of the birds within 36-48 hours. Since natural killer (NK) cells have been shown to play an important role in influenza-specific immunity, we hypothesise that NK cells are involved in this difference in pathogenicity. To investigate this, the role of chicken NK-cells in LPAI virus infection was studied. Next activation of lung NK cells upon HPAI virus infection was analysed. Infection with a H9N2 LPAI virus resulted in the presence of viral RNA in the lungs which coincided with enhanced activation of lung NK cells. The presence of H5N1 viruses, measured by detection of viral RNA, did not induce activation of lung NK cells. This suggests that decreased NK-cell activation may be one of the mechanisms associated with the enhanced pathogenicity of H5N1 viruses.
Jin L, Walker A S, Fu G, Harvey-Samuel T, Dafa'alla T, Miles A, Marubbi T, Granville D, Humphrey-Jones N, O'Connell S, Morrison N I, Alphey L (2013)

Engineered female-specific lethality for control of pest Lepidoptera

ACS Synthetic Biology 2 (3), 160-166
Publisher’s version: http://dx.doi.org/10.1021/sb300123m

Abstract

The sterile insect technique (SIT) is a pest control strategy involving the mass release of radiation-sterilized insects, which reduce the target population through nonviable matings. In Lepidoptera, SIT could be more broadly applicable if the deleterious effects of sterilization by irradiation could be avoided. Moreover, male-only release can improve the efficacy of SIT. Adequate methods of male-only production in Lepidoptera are currently lacking, in contrast to some Diptera. We describe a synthetic genetic system that allows male-only moth production for SIT and also replaces radiation sterilization with inherited female-specific lethality. We sequenced and characterized the doublesex (dsx) gene from the pink bollworm (Pectinophora gossypiella). Sex-alternate splicing from dsx was used to develop a conditional lethal genetic sexing system in two pest moths: the diamondback moth (Plutella xylostella) and pink bollworm. This system shows promise for enhancing existing pink bollworm SIT, as well as broadening SIT-type control to diamondback moth and other Lepidoptera.
Juleff N, Valdazo-Gonzalez B, Wadsworth J, Wright C F, Charleston B, Paton D J, King D P, Knowles N J (2013)

Accumulation of nucleotide substitutions occurring during experimental transmission of foot-and-mouth disease virus

Journal of General Virology 94 (1), 108-119
Publisher’s version: http://dx.doi.org/10.1099/vir.0.046029-0

Abstract

Analysis of full-genome sequences was previously used to trace the origin and transmission pathways of foot-and-mouth disease virus (FMDV) outbreaks in the UK in 2001 and 2007. Interpretation of these data was sometimes at variance with conventional epidemiological tracing, and was also used to predict the presence of undisclosed infected premises that were later discovered during serological surveillance. Here we report the genome changes associated with sequential passage of a highly BHK-21-cell-adapted (heparan sulphate-binding) strain of FMDV arising from two independent transmission chains in cattle. In vivo virus replication rapidly selected for a wild-type variant with an amino acid substitution at VP356. Full-genome sequence analysis clearly demonstrated sequence divergence during parallel passage. The genetic diversity generated over the course of infection and the rate at which these changes became fixed and were transmitted between cattle occurred at a rate sufficient to enable reliable tracing of transmission pathways at the level of the individual animal. However, tracing of transmission pathways was only clear when sequences from epithelial lesions were compared. Sequences derived from oesophageal–pharyngeal scrapings were problematic to interpret, with a varying number of ambiguities suggestive of a more diverse virus population. These findings will help to correctly interpret full-genome sequence analyses to resolve transmission pathways within future FMDV epidemics.
Kelly L, Brouwer A, Wilson A, Gale P, Snary E, Ross D, de Vos C J (2013)

Epidemic threats to the European Union: expert views on six virus groups

Transboundary and Emerging Diseases 60 (4), 360-369
Publisher’s version: http://dx.doi.org/10.1111/j.1865-1682.2012.01355.x

Abstract

In recent years, several animal disease epidemics have occurred within the European Union (EU). At the 4th Annual Meeting of the EPIZONE network (7–10 June 2010, St. Malo, France), an interactive session was run to elicit the opinions of delegates on a pre-defined list of epidemic threats to the EU. Responses from over 190 delegates, to questions relating to impact and likelihood, were used to rank six virus groups with respect to their perceived threat now (2010) and in 2020. The combined opinions of all delegates suggested that, from the pre-selected list of virus groups, foot-and-mouth disease and influenza are currently of most concern. Delegates thought that influenza would be less of a threat and zoonotic arboviruses would be more of a threat in 2020. Although the virus group rankings should not be taken as definitive, the results could be used in conjunction with experimental and field data, by scientists, policy-makers and stakeholders when assessing and managing risks associated with these virus groups.

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