Veterinary Laboratories Agency VLA

Addlestone, United Kingdom

Veterinary Laboratories Agency VLA

Addlestone, United Kingdom
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Wall R.,University of Bristol | Bates P.,Veterinary Laboratories Agency VLA
Veterinary Parasitology | Year: 2011

A series of in vitro and in vivo assays were conducted to examine the effects of trans-cinnamic acid ethyl ester on Psoroptes mange mites. In vitro, 24h after exposure to the test material at concentrations of 10, 1 or 0.1% (v/v), 100, 74 and 20% of mites had died, respectively, compared to 8% following exposure to the control (0.05% SDS only). The different life-cycle stages were affected similarly by the test compound. The concentration required to produce 95% mortality 24h after exposure to the test compound was 6.29% (95% confidence interval 4.98-8.88). Tarsal contact of the mites with the test compound was also sufficient to achieve high levels of mortality; 100% death was observed when the mites were placed in contact with either sheep skin circles treated to give 0.01ml/cm2 or polyester cloth circles treated with 0.03ml/cm2. However, the residual activity of both skin and cloth treated with 0.03ml/cm2 was completely lost after 7 days. In vivo, trans-cinnamic acid ethyl ester suspended in 2% (w/v) lecithin was applied as a spray formulation to eight sheep with active artificial infestations of sheep scab. Seven of the 8 treated sheep were cured and remained completely clear of scab mites for 56 days. However, 33 days after treatment 2 adult female mites were observed on one of the eight treated sheep and the mite population on this sheep subsequently recovered. In contrast, in a control group of two infested sheep, treated with a 2% (w/v) lecithin only, mite populations increased as expected in a typical scab infestation, but eventually self-cured in one animal. The data suggest that, with appropriate development of suitable application technology, trans-cinnamic acid ethyl ester could have a role as a potential therapeutic treatment for active sheep scab, however the short residual period of activity is likely to limit its use in commercial sheep flocks. © 2010 Elsevier B.V.


Hamza E.,University of Bern | Steinbach F.,Veterinary Laboratories Agency VLA | Marti E.,University of Bern
Veterinary Immunology and Immunopathology | Year: 2012

Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis caused by bites of midges from the genus Culicoides. We have shown previously that peripheral blood mononuclear cells (PBMC) from IBH-affected horses produce higher levels of IL-4 and lower levels of IL-10 and TGF-β1 than those from healthy horses, suggesting that IBH is associated with a reduced regulatory immune response. FoxP3 is a crucial marker of regulatory T cells (Tregs). Here we have determined the proportion of CD4+CD25+FoxP3+ T cells by flow cytometry in PBMC directly after isolation or after stimulation with Culicoides extract or a control antigen (Tetanus Toxoid). There were no differences between healthy and IBH horses either in the proportion of FoxP3+CD4+CD25+ cells in freshly isolated PBMC or in the following stimulation with Tetanus Toxoid. However, upon stimulation of PBMC with the allergen, expression of FoxP3 by CD4+CD25+high and CD4+CD25+dim cells was significantly higher in healthy than in IBH horses. Addition of recombinant IL-4 to PBMC from healthy horses stimulated with the allergen significantly decreased the proportion of FoxP3 expressing cells within CD4+CD25+high. These results suggest that IBH is associated with a decreased number of allergen-induced Tregs. This could be a consequence of the increased IL-4 production by PBMC of IBH-affected horses. © 2011 Elsevier B.V.


Ibrahim S.,Institute for Zoo and Wildlife Research IZW | Ibrahim S.,Veterinary Serum and Vaccines Research Institute VSVRI | Steinbach F.,Veterinary Laboratories Agency VLA
Veterinary Immunology and Immunopathology | Year: 2012

Earlier studies investigating the cross-reactivity of antibodies submitted to the HLDA8 had used flow cytometry as a method of choice to screen mAbs for reactivity with equine leukocytes, including two-color flow-cytometry to characterize the lymphocyte population they detect. In addition, immuno-histochemistry (IHC) was used to detect distribution of positive cells in lymphoid tissue sections. In this study we performed immunoprecipitation (IP) to complement the previous results and add valuable information regarding the molecules detected by the cross-reacting antibodies. Surface molecules from primary equine PBMC or the equine cell line T8888 were biotinylated prior to precipitation to determine the molecular weight of the corresponding molecules in a western blot using streptavidin-AP. 21 out of 24 mAbs precipitated the molecules with a MW corresponding to its human orthologue. Positive mAbs were directed against CD2, CD5, CD11a, CD11b, CD14, CD18, CD21, CD44, CD83, CD91, CD172a, MHCI and MHCII. Three mAbs directed against CD49d, CD163, and CD206 which were unambiguously identified earlier by flow cytometry failed to immunoprecipitate the corresponding CD molecule. MAbs detecting CD molecules which are expressed internally like CD68 and mAbs of IgM class could not be included into this approach. © 2011.


Bentley S.D.,Wellcome Trust Sanger Institute | Comas I.,Genomics and Health Unit | Comas I.,UK National Institute for Medical Research | Bryant J.M.,Wellcome Trust Sanger Institute | And 17 more authors.
PLoS Neglected Tropical Diseases | Year: 2012

Background: M. africanum West African 2 constitutes an ancient lineage of the M. tuberculosis complex that commonly causes human tuberculosis in West Africa and has an attenuated phenotype relative to M. tuberculosis. Methodology/Principal Findings: In search of candidate genes underlying these differences, the genome of M. africanum West African 2 was sequenced using classical capillary sequencing techniques. Our findings reveal a unique sequence, RD900, that was independently lost during the evolution of two important lineages within the complex: the "modern" M. tuberculosis group and the lineage leading to M. bovis. Closely related to M. bovis and other animal strains within the M. tuberculosis complex, M. africanum West African 2 shares an abundance of pseudogenes with M. bovis but also with M. africanum West African clade 1. Comparison with other strains of the M. tuberculosis complex revealed pseudogenes events in all the known lineages pointing toward ongoing genome erosion likely due to increased genetic drift and relaxed selection linked to serial transmission-bottlenecks and an intracellular lifestyle. Conclusions/Significance: The genomic differences identified between M. africanum West African 2 and the other strains of the Mycobacterium tuberculosis complex may explain its attenuated phenotype, and pave the way for targeted experiments to elucidate the phenotypic characteristic of M. africanum. Moreover, availability of the whole genome data allows for verification of conservation of targets used for the next generation of diagnostics and vaccines, in order to ensure similar efficacy in West Africa. © 2012 Bentley et al.


Kauko T.,Finnish National Institute for Health and Welfare | Haukka K.,Finnish National Institute for Health and Welfare | AbuOun M.,Veterinary Laboratories Agency VLA | Anjum M.F.,Veterinary Laboratories Agency VLA | And 2 more authors.
European Journal of Clinical Microbiology and Infectious Diseases | Year: 2010

The Phenotype MicroArray™ (PM) technology was used to study the metabolic characteristics of 29 Salmonella strains belonging to seven serotypes of S. enterica spp. enterica. Strains of serotypes Typhimurium (six strains among definite phage types DTs 1, 40 and 104) and Agona (two strains) were tested for 949 substrates, Enteritidis (six strains of phage type PT1), Give, Hvittingfoss, Infantis and Newport strains (two of each) were tested for 190 substrates and seven other Agona strains for 95 substrates. The strains represented 18 genotypes in pulsed-field gel electrophoresis (PFGE). Among 949 substrates, 18 were identified that could be used to differentiate between the strains of those seven serotypes or within a single serotype. Unique metabolic differences between the Finnish endemic Typhimurium DT1 and Agona strains were detected, for example, in the metabolism of D-tagatose, D-galactonic acid ?-lactone and L-proline as a carbon source. Thus, the PM technique is a useful tool for identifying potential differential markers on a metabolic basis that could be used for epidemiological surveillance. © Springer-Verlag 2010.


Gonzalez L.,Veterinary Laboratories Agency VLA | Siso S.,Veterinary Laboratories Agency VLA | Monleon E.,University of Zaragoza | Casalone C.,Instituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle dAosta IZS | And 9 more authors.
Journal of General Virology | Year: 2010

Variability of pathological phenotypes within classical sheep scrapie cases has been reported for some time, but in many instances it has been attributed to differences in the PRNP genotype of the host. To address this issue we have examined by immunohistochemistry (IHC) and Western blotting (WB) for the disease-associated form of the prion protein (PrPd), the brains of 23 sheep from five European countries, all of which were of the same ARQ/ARQ genotype. As a result of IHC examinations, sheep were distributed into five groups with different phenotypes and the groups were the same regardless of the scoring method used, 'long' or 'short' PrPd profiling. The groups made did not respond to the geographical origin of the cases and did not correlate with the vacuolar lesion profiles, which showed a high individual variability. Discriminatory IHC and WB methods coincided to detect a 'CH1641-like' case but otherwise correlated poorly in the classification of disease phenotypes. No other polymorphisms of the PRNP gene were found that could account for the pathological differences, except perhaps for a sheep from Spain with a mutation at codon 103 and a unique pathological phenotype. Preliminary evidence indicates that those different IHC phenotypes correlate with distinct biological properties on bioassay, suggesting that they are indicative of strain diversity. We therefore conclude that natural scrapie strains exist and that they can be revealed by detailed pathological examinations, which can be harmonized between laboratories to produce comparable results. © 2010 Crown copyright.


Santos A.C.,London School of Hygiene and Tropical Medicine | Roberts J.A.,London School of Hygiene and Tropical Medicine | Cook A.J.C.,Veterinary Laboratories Agency VLA | Simons R.,Veterinary Laboratories Agency VLA | And 5 more authors.
Epidemiology and Infection | Year: 2011

This is the first study comparing societal costs of acute illness with Salmonella Typhimurium (ST) and Salmonella Enteritidis (SE) in the UK. It included the cost and severity of the illness and explored the impact of each Salmonella serovar on the patients, their families, the NHS, and the wider economy. The study ascertained confirmed cases of ST and SE between July and November 2008. The mean costs per case were £1282 (ST) and £993 (SE). The indirect costs associated with the work-time lost by the case, parents, or carers were £409 (ST) and £228 (SE); this difference was statistically significant. The aggregate cost of ST and SE identified using laboratory test results for the UK as a whole was estimated as £6.5 million. Work-time lost and caring activities are cost categories that are not frequently investigated within the infectious intestinal disease literature, although they represent an important societal cost. © Copyright Cambridge University Press 2010.


Bublot M.,Merial S.A.S. | Manvell R.J.,Veterinary Laboratories Agency VLA | Shell W.,Veterinary Laboratories Agency VLA | Brown I.H.,Veterinary Laboratories Agency VLA
Avian Diseases | Year: 2010

The objective of the study was to compare efficacy of two fowlpox (FP) vector vaccines (FP-AI) against H5N1 highly pathogenic avian influenza (HPAI): one (vFP89) expressing the native hemagglutinin (HA) gene from H5N8 A/turkey/ Ireland/1378/83 and the other (vFP2211) expressing a modified synthetic HA gene from H5N1 A/chicken/Indonesia/7/2003. Four groups of 20 1-day-old specific-pathogen-free chickens were made: Groups 1 and 2 were immunized with 3 log10 tissueculture infectious dose 50% (TCID50) of vFP89 and vFP2211, respectively, whereas group 3 was immunized with vFP89, but received a booster immunization at 2 wk of age with an inactivated vaccine containing A/turkey/Wisconsin/68 H5N9 virus (inH5N9); group 4 was left unvaccinated. Ten birds from each group were challenged on day 21 with A/turkey/Turkey/1/2005 clade 2.2 H5N1 HPAI virus. The 10 other chickens from each group were put in contact with their groupmates on day 22. FP-AI induced low hemagglutination inhibition (HI) titers before challenge (GMT <4 log 2) and an HI titer boost was observed 1 wk after the inH5N9 boost. All directly challenged and 9/10 nonvaccinated contact chickens died after challenge (mean death time of 2.3 and 6.1 days, respectively) and most of them shed virus before death via cloacal and buccal routes. All vaccinated birds were clinically protected from HPAI challenge. One (vFP2211), 2 (vFP89+inact.), or 3 (vFP89) out of the 10 directly challenged vaccinated chickens shed virus via the buccal route 2-5 days postinfection. No shedding was detected in the contact-challenged vaccinated birds. Altogether, these data show excellent levels of protection in all three vaccinated groups, and therefore no detectable effect of the origin of the inserted H5 gene on protection under these tested conditions. © 2010 American Association of Avian Pathologists.


Hamza E.,University of Bern | Gerber V.,University of Bern | Steinbach F.,Veterinary Laboratories Agency VLA | Marti E.,University of Bern
Immunology | Year: 2011

Horses are particularly prone to allergic and autoimmune diseases, but little information about equine regulatory T cells (Treg) is currently available. The aim of this study therefore was to investigate the existence of CD4 + Treg cells in horses, determine their suppressive function as well as their mechanism of action. Freshly isolated peripheral blood mononuclear cells (PBMC) from healthy horses were examined for CD4, CD25 and forkhead box P3 (FoxP3) expression. We show that equine FoxP3 is expressed constitutively by a population of CD4 +CD25 + T cells, mainly in the CD4 +CD25 high subpopulation. Proliferation of CD4 +CD25 - sorted cells stimulated with irradiated allogenic PBMC was significantly suppressed in co-culture with CD4 +CD25 high sorted cells in a dose-dependent manner. The mechanism of suppression by the CD4 +CD25 high cell population is mediated by close contact as well as interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) and probably other factors. In addition, we studied the in vitro induction of CD4 + Treg and their characteristics compared to those of freshly isolated CD4 + Treg cells. Upon stimulation with a combination of concanavalin A, TGF-β1 and IL-2, CD4 +CD25 + T cells which express FoxP3 and have suppressive capability were induced from CD4 +CD25 - cells. The induced CD4 +CD25 high express higher levels of IL-10 and TGF-β1 mRNA compared to the freshly isolated ones. Thus, in horses as in man, the circulating CD4 +CD25 high subpopulation contains natural Treg cells and functional Treg can be induced in vitro upon appropriate stimulation. Our study provides the first evidence of the regulatory function of CD4 +CD25 + cells in horses and offers insights into ex vivo manipulation of Treg cells. © 2011 The Authors. Immunology © 2011 Blackwell Publishing Ltd.


Smith R.P.,Veterinary Laboratories Agency VLA | Chalmers R.M.,Singleton Hospital | Mueller-Doblies D.,Veterinary Laboratories Agency VLA | Clifton-Hadley F.A.,Veterinary Laboratories Agency VLA | And 5 more authors.
Preventive Veterinary Medicine | Year: 2010

The study investigates farms suspected of being sources of zoonotic human cryptosporidiosis. A variety of implicated farm animal species were sampled and tested to detect Cryptosporidium oocysts and investigate genetic linkage with human patients. Risk factor information was collected from each farm and analysed by multivariable logistic regression to detect significant associations between factors and Cryptosporidium in animals. The results showed that average sample prevalence of Cryptosporidium infection was highest in cattle, sheep and pigs (∼40-50%), in the mid-range in goats and horses (20-25%) and lowest in rabbits/guinea pigs, chickens and other birds (∼4-7%). A single sample from a farm dog was also positive. Cryptosporidium parvum, which has zoonotic potential, was the commonest species and was most likely to be present in cattle and, to a lesser extent, in sheep. In particular, young calves and lambs shed C. parvum and this finding was corroborated in a statistical model which demonstrated that samples from groups of preweaned animals were 11 times, and immature animal groups six times, more likely to be positive than groups of adult animals, and that samples from a farm with a cattle enterprise were twice as likely to be positive than farms without a cattle enterprise. On seven out of eight farms, at least one C. parvum isolate from an animal sample was indistinguishable at the gp60 locus from those found in the human patients, indicating that farm animals are a likely source of infection for humans. Crown Copyright © 2010.

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