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

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Dixon L K, Escribano J, Martins C, Rock D L, Salas M L, Wilkinson P J (2005)

The Asfarviridae

Virus Taxonomy: classification and nomenclature of viruses. (VIII report of the International Committee on Taxonomy of Viruses), 135-143
Publisher’s version:
Edwards M J, Buchatska E, Ashton M, Montoya M, Bickle Q D, Borrow P (2005)

Reciprocal immunomodulation in a schistosome and hepatotropic virus coinfection model

Journal of Immunology 175 (10), 6275-6285
Publisher’s version: http://dx.doi.org/10.4049/jimmunol.175.10.6275

Abstract

Human coinfection with the helminth parasite Schistosoma mansoni and hepatitis B and hepatitis C viruses is associated with increased hepatic viral burdens and severe liver pathology. In this study we developed a murine S. mansonillymphocytic choriomeningitis virus (LCMV) coinfection model that reproduces the enhanced viral replication and liver pathology observed in human coinfections, and used this model to explore the mechanisms involved. Viral coinfection during the Th2-dominated granulomatous phase of the schistosome infection resulted in induction of a strong LCMV-specific T cell response, with infiltration of high numbers of LCMV-specific IFN-gamma-producing CD8(+) cells into the liver. This was associated with suppression of production of the Th2 cytokines dominant during S. mansoni infection and a rapid increase in morbidity, linked to hepatotoxicity. Interestingly, the liver of coinfected mice was extremely susceptible to viral replication. This correlated with a reduced intrahepatic type I IFN response following virus infection. Schistosome egg Ags were found to suppress the type I IFN response induced in murine bone marrow-derived dendritic cells by polyinosinic-polycytidylic acid. These results suggest that suppression of the antiviral type I IFN response by schistosome egg Ags in vivo predisposes the liver to enhanced viral replication with ensuing immunopathological consequences, findings that maybe paralleled inhuman schistosome/hepatotropic virus coinfections.
Faburay B, Munstermann S, Geysen D, Bell-Sakyi L, Ceesay A, Bodaan C, Jongejan F (2005)

Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in The Gambia

Clinical and Diagnostic Laboratory Immunology 12 (4), 508-512
Publisher’s version: http://dx.doi.org/10.1128/cdli.12.4.508-512.2005

Abstract

Using the MAP1-B enzyme-linked immunosorbent assay, we tested 1,318 serum samples collected from sheep and goats at 28 sites in the five divisions of The Gambia to determine the Ehrlichia ruminantium seroprevalence rates and to assess the risk for heartwater. About half (51.6 %) of 639 sheep were positive, with seroprevalence rates per site varying between 6.9 % and 100 %. The highest seroprevallence was detected in the western part of the country (88.1 % in the Western Division and 62.1 % in the Lower River Division). Sheep in the two easterly divisions (Central River and Upper River divisions) showed the lowest seroprevalence of 29.3 % and 32.4 %, respectively, while those in the North Bank Division showed an intermediate prevalence of 40.6 %. In goats, less than one-third (30.3 %) of 679 animals tested were positive. The highest seroprevalence was detected in goats in the North Bank Division (59 %) and Western Division (44.1 %). Goats in the Lower River Division showed an intermediate level of 21.9 %, whereas the lowest rates were found in the eastern part of the country (4.8 % in the Central River Division and 2.3 % in the Upper River Division). At nearly all sites, seroprevalence rates were higher in sheep than in goats. The results show a gradient of increasing heartwater risk for susceptible small ruminants from the east to the west of The Gambia. These findings need to be taken into consideration when future livestock-upgrading programs are implemented.
Gong P, Epton M J, Fu G L, Scaife S, Hiscox A, Condon K C, Condon G C, Morrison N I, Kelly D W, Dafa'alla T, Coleman P G, Alphey L (2005)

A dominant lethal genetic system for autocidal control of the Mediterranean fruitfly

Nature Biotechnology 23 (4), 453-456
Publisher’s version: http://dx.doi.org/10.1038/nbt1071

Abstract

The Sterile Insect Technique (SIT) used to control insect pests relies on the release of large numbers of radiation-sterilized insects. Irradiation can have a negative impact on the subsequent performance of the released insects(1-4) and therefore on the cost and effectiveness of a control program(5). This and other problems associated with current SIT programs could be overcome by the use of recombinant DNA methods and molecular genetics(6-12). Here we describe the construction of strains of the Mediterranean fruit fly (medfly) harboring a tetracycline-repressible transactivator (tTA) that causes lethality in early developmental stages of the heterozygous progeny but has little effect on the survival of the parental transgenic tTA insects. We show that these properties should prove advantageous for the implementation of insect pest control programs.

Shaw A E, Reid S M, King D P, Hutchings G H, Ferris N P (2004)

Enhanced laboratory diagnosis of foot and mouth disease by real-time polymerase chain reaction

Revue Scientifique et Technique 23 (3), 1003-1009
Publisher’s version: http://web.oie.int/boutique/extrait/28shaw10031009.pdf

Abstract

The performance of an automated real-time reverse transcription polymerase chain reaction (RT-PCR) was compared to virus isolation (VI) in cell culture and antigen detection enzyme-linked immunosorbent assay (ELISA) for the laboratory diagnosis of foot and mouth disease (FMD). The World Reference Laboratory for FMD in Woking, the United Kingdom, examined a collection of 334 epithelia received from eighteen countries between August 2002 and January 2004. The results showed that all VI positive (n = 195) and VI and ELISA positive samples combined (n = 204) were also positive by RT-PCR. Depending on the cut-off used, FMD virus genome was detected in a minimum of an additional 60 samples (18% of all samples tested). Furthermore, the RT-PCR generated results in less than one day from test commencement in contrast to up to 4 days to define some positive and all negative samples by VI. The study demonstrates that real-time RT-PCR provides an extremely sensitive and rapid procedure for improved laboratory diagnosis of FMD.

Beard P M, Baines J D (2004)

The DNA cleavage and packaging protein encoded by the U(L)33 gene of herpes simplex virus 1 associates with capsids

Virology 324 (2), 475-482
Publisher’s version: http://dx.doi.org/10.1016/j.virol.2004.03.044

Abstract

The U(L)33 gene of herpes simplex virus 1 (HSV-1) encodes a protein (pU(L)33) that is essential for the cleavage and packaging of concatameric herpesvirus DNA into preformed capsids. Previous data have suggested that the U(L)33 protein interacts with the cleavage and packaging proteins encoded by U(L)15 and U(L)28 that are known to associate with capsids. Examination of purified A capsids that lack DNA and are derived from aborted packaging events, B capsids that lack DNA, and C capsids that contain DNA revealed an association of the U(L)33 protein with all three capsid types. More U(L)33 protein was detected in A capsids than was present in B capsids. Capsid association was susceptible to guanidine-HCl treatment and independent of the presence of U(L)15 or U(L)28. Capsid association of pU(L)33 was also independent of U(L)6, which is believed to encode the portal into which DNA is inserted. These data suggest that pU(L)33 may act as part of the capsid-associated molecular machinery that translocates cleaved genomic DNA into the capsid interior.

Beard P M, Duffy C, Baines J D (2004)

Quantification of the DNA cleavage and packaging proteins U(L)15 and U(L)28 in A and B capsids of herpes simplex virus type 1

Journal of Virology 78 (3), 1367-1374
Publisher’s version: http://dx.doi.org/10.1128/jvi.78.3.1367-1374.2004

Abstract

The proteins produced by the herpes simplex virus type 1 (HSV-1) genes U(L)15 and U(L)28 are believed to form part of the terminase enzyme, a protein complex essential for the cleavage of newly synthesized, concatameric herpesvirus DNA and the packaging of the resultant genome lengths into preformed capsids. This work describes the purification of recombinant forms of PU(L)15 and pU(L)28, which allowed the calculation of the average number of copies of each protein in A and B capsids and in capsids lacking the putative portal encoded by U(L)6. On average, 1.0 (+/-0.29 [standard deviation]) copies of PU(L)15 and 2.4 (+/-0.97) copies of pU(L)28 were present in B capsids, 1.2 (+/-0.72) copies of PU(L)15 and 1.5 (+/-0.86) copies of pU(L)28 were found in mutant capsids lacking the putative portal protein pU(L)6, and approximately 12.0 (+/-5.63) Copies of pU(L)15 and 0.6 (+/-0.32) copies of pU(L)28 were present in each A capsid. These results suggest that the packaging machine is partly comprised of approximately 12 copies of pU(L)15, as found in A capsids, with wild-type B and mutant U(L)6(-) capsids containing an incomplete complement of cleavage and packaging proteins. These results are consistent with observations that B capsids form by default in the absence of packaging machinery in vitro and in vivo. In contrast, A capsids may be the result of initiated but aborted attempts at DNA packaging, resulting in the retention of at least part of the DNA packaging machinery.

Bell-Sakyi L (2004)

Ehrlichia ruminantium grows in cell lines from four ixodid tick genera

Journal of Comparative Pathology 130 (4), 285-293
Publisher’s version: http://dx.doi.org/10.1016/j.jcpa.2003.12.002

Abstract

Continuous cell lines from the ticks Amblyomma variegatum, Boophilus decoloratus, Boophilus microplus, Hyalomma anatolicum anatolicum, Ixodes scapularis, Ixodes ricinus and Rhipicephalus appendiculatus were tested for ability to support growth of the rickettsial pathogen Ehrlichia (previously Cowdria) ruminantium. Five E.ruminantium isolates, from West Africa, South Africa and the French West Indies, were used. Twelve tick cell lines were inoculated with E.ruminantium derived either from cultures of a bovine endothelial cell strain designated BPC or from other tick cell lines. Successful infection resulted in either continuous growth (in which the pathogen/cell line system could be perpetuated through regular subculture on fresh, uninfected cells for many months or years) or finite growth (in which the pathogen disappeared after one or a few subcultures). Infection with E.ruminantium from BPC was established in I. scapularis, I. ricinus and A. variegatum cell lines; E. ruminantium was transferred from these infected cell lines to B. decoloralus, B. microplus and R. appendiculatus cell lines. H. a. anatolicum cells could not be infected with E.ruminantium by any procedure. All five E.ruminantium isolates grew continuously in at least one tick cell line at temperatures between 28 degreesC and 37 degreesC; three of the isolates were successfully re-established in BPC following prolonged maintenance in tick cells. This study demonstrates that E.ruminantium is not intrinsically restricted to growth in cells from ticks of the natural vector genus Amblyomma.
Bell-Sakyi L, Koney E B M, Dogbey O, Walker A R (2004)

Ehrlichia ruminantium seroprevalence in domestic ruminants in Ghana - I. Longitudinal survey in the Greater Accra Region

Veterinary Microbiology 100 (3-4), 175-188
Publisher’s version: http://dx.doi.org/10.1016/j.vetmic.2004.02.010

Abstract

Serum samples collected monthly over a 34-month period from cattle, sheep and goats in the Greater Accra Region of Ghana were tested for antibodies to Ehrlichia (previously Cowdria) ruminantium, the causative agent of heartwater, by polyclonal competitive ELISA (PC-ELISA). Maternal antibodies, detected in about half of animals followed from under 1 month old, declined to negative levels within 2-4 months. Amblyomma variegatum tick vectors were present on livestock in rural areas throughout the year, and first seroconversion occurred at any age, although the majority of calves seroconverted between 1 and 10 months old, sheep by 11 months, and goats by 7 months. All the cattle in the study became seropositive by 20 months of age, except one animal which subsequently died of heartwater. Following seroconversion, 25% of bovine sera tested negative in the PC-ELISA. Just over half the sheep in the survey seroconverted before or during the study period; following seroconversion, less than 3% of ovine sera became PC-ELISA negative. About a quarter of the goats seroconverted, and 34% of their post-seroconversion sera tested negative in the PC-ELISA. Overall, the serology indicated that virtually all cattle on the survey farms were exposed to E. ruminantium without suffering disease, but that a substantial proportion of sheep and goats escaped exposure and thus formed a susceptible population. E. ruminantium was detected in brains of 14, 36 and 4% of cattle, sheep and goats submitted for post mortem at the Accra Veterinary Laboratory, indicating that sheep were most at risk from heartwater disease.
Bell-Sakyi L, Koney E B M, Dogbey O, Walker A R (2004)

Incidence and prevalence of tick-borne haemoparasites in domestic ruminants in Ghana

Veterinary Parasitology 124 (1-2), 25-42
Publisher’s version: http://dx.doi.org/10.1016/j.vetpar.2004.05.027

Abstract

Giemsa-stained thin blood smears prepared monthly from cattle, sheep and goats in the Greater Accra region of Ghana between May 4994 and December 1996 were examined for presence of tick-home haemoparasites. The majority of animals were less than 2 months old at the start of the survey. Monthly and cumulative incidences are presented of Anaplasma sp., Babesia bigemina, Borrelia sp., Eperythrozoon sp., Theileria mutans and Theileria velifera in cattle, Anaplasma sp., Borrelia sp., and Theileria sp. in sheep, and Anaplasma sp. in goats. T. mutans was the commonest parasite in cattle, with 100% incidence in calves by 10 months of age, and Anaplasma was commonest in small ruminants. The relative prevalence of these haemoparasites in blood smears from cattle, sheep and goats sampled on a single occasion at sites in all 10 regions of Ghana was found to be similar, though actual infection rates were lower. Packed cell volume (PCV) measurements from the sampled animals are also presented; no seasonal trends were evident in the PCV of the cattle, sheep and goats sampled monthly. In animals sampled on a single occasion, mean PCV was significantly higher in cattle and sheep without detectable haemoparasite infection, and in cattle was lowest in animals positive for both Babesia and Anaplasma, while there was no difference in mean PCV levels between parasitised and non-parasitised goats.

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