Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.184 (LasR)
 897 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An indirect enzyme-linked immunosorbent assay was used for the screening of horse sera from The Gambia for antibodies against African horse sickness virus (AHSV). The AHSV antigen used for coating was semipurified according to the method of Manning and Chen (Curr. Microbiol. 4:381, 1980); control mock-infected Vero cell antigen was treated in the same manner. A total of 459 horse serum samples were assayed at a single dilution (1:10), and their reactivities were compared with those of reference positive anti-AHSV and reference negative horse sera. A total of 81% of the horse serum samples clearly contained antibodies against AHSV; this consisted of 18% (of the total number of serum samples) strongly positive, 46.5% moderately positive, and 16.5% weakly but still clearly positive. Such results suggest a high prevalence of AHSV in the regions from whence the samples originated. Reports from investigations in other countries in this area of West Africa have also shown a high prevalence for anti-AHSV antibodies in equids. The question is raised as to how the animals became seropositive and whether the observations represent an increased resistance of horses living in a region in which AHS is enzootic.
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PMID:Seroepidemiological study of African horse sickness virus in The Gambia. 837 Jul 60

To elucidate the role that donkeys may play in African horse sickness virus (AHSV) persistence during inter-epizootic periods we looked for clinical signs of infection and studied the viraemia and neutralising antibody kinetics in 3 immunocompetent and 3 immunosuppressed donkeys inoculated with AHSV-4. None of the donkeys developed signs of AHS. However infectious AHSV was isolated from the blood of the immunocompetent donkeys for up to 17 days post infection (dpi) and viral antigens were detected for up to 28 dpi. Immune cells also increased significantly from 35 to 60 dpi. There was no evidence of a recrudescence of viraemia following immunosuppression of these donkeys at 90 dpi despite a decrease in the numbers of immune cells. Infectious virus was not isolated from the blood of donkeys that had been immunosuppressed, prior to AHSV inoculation. However viral antigens were detected for up to 35 dpi. The titres of AHSV-specific neutralising antibodies and the number of immune cells were also significantly lower than in immunocompetent animals. Our findings suggest that donkeys may be able to play a role in the epidemiology of AHS but the ability of vectors to become infected by feeding upon viraemic donkeys needs to be assessed before the significance of that role can be fully understood.
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PMID:Clinical, virological and immune responses of normal and immunosuppressed donkeys (Equus asinus africanus) after inoculation with African horse sickness virus. 978 95

African horse sickness virus (AHSV) antigen was demonstrated immunohistochemically in formalin-fixed, paraffin-embedded sections of tissues collected from three ponies suffering from the peracute form of the disease and from one pony affected by the fever form. The pattern of the antigen distribution indicated a particular organ tropism characterised by an accumulation of AHSV antigen in cardio-pulmonary tissues of the animals with the peracute disease and in the spleen of the pony with the fever form. AHSV antigen was identified in endothelial cells of small blood vessels, particularly capillaries and in large mono-nuclear cells resembling macrophages or reticular cells of lymphatic tissues. Occasional circulating mononuclear cells with the morphology of monocytes were also positively stained within the larger vessels. The immunohistochemical results confirm earlier work suggesting that AHSV may have different tropisms to particular organs during various forms of the disease and that different target cell populations exist in vivo. Immunohistochemistry may be an additional useful method for diagnostic and research purposes in AHS.
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PMID:Immunohistochemical demonstration of African horse sickness viral antigen in tissues of experimentally infected equines. 978 96

The oral susceptibilities of 17 Culicoides species to infection with African horse sickness virus (AHSV) serotypes 3, 5 and 8 were determined by feeding field-collected midges on AHSV infected horse blood. The mean titres of virus in the bloodmeals for the three serotypes of AHSV were between 5.7 and 6.5 log10 TCID50/ml. Virus was detected, after 10 days incubation at 23.5 degrees C, in the Culicoides imicola Kieffer (Diptera: Ceratopogonidae) that had fed on blood containing AHSV 5 (8.5%) and 8 (26.8%), and in the Culicoides bolitinos Meiswinkel that had fed on AHSV 3 (3.8%), 5 (20.6%) and 8 (1.7%). Although 44.4% of the C. imicola were shown to have ingested AHSV 3 immediately after feeding, no virus was detected in 96 C. imicola after incubation. The relatively high titres of virus recorded in individual midges of both species after 10 days incubation suggested a fully disseminated infection. Previously, C. imicola was considered to be the only field vector of AHSV in Africa. Identifying C. bolitinos as a potential vector for AHSV is an important finding, which if proven will have a significant impact on our understanding of the epidemiology of AHS. No AHSVs could be detected in the other 15 species of Culicoides assayed, which suggests that some of the southern African Culicoides species are refractory to AHSV infection. However, further work with larger numbers of each species will be necessary to confirm this observation.
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PMID:African horse sickness epidemiology: vector competence of south african Culicoides species for virus serotypes 3, 5 and 8. 1101 30

This paper describes the production and purification of a group-specific recombinant protein VP7 of African horse sickness virus serotype 3 (AHSV-3) and validation of an I-ELISA for the detection of IgG-antibodies to VP7 in horse sera. Baculovirus-expressed VP7 crystals were purified from infected insect cells. Analytical accuracy of the I-ELISA was examined using sera (n = 38) from an experimentally infected horse, from foals born to vaccinated mares, from guinea-pigs immunized with nine serotypes of AHSV, and from sera of animals infected with other orbiviruses. Compared to traditional serological assays, the I-ELISA was more sensitive in detection of the earliest immunological response in an infected horse and declining levels of maternal immunity in foals. Antibodies to all nine serotypes of AHSV could be detected. Cross-reactivity to related orbiviruses was not observed. Diagnostic accuracy of the I-ELISA was assessed by testing sera from vaccinated horses (n = 358) residing in AHS-enzootic areas and from unvaccinated horses (n = 481) residing in an AHS-free area. Sera were categorised as positive or negative for antibodies to AHSV using virus neutralisation tests. The TG-ROC analysis was used for the selection of the cut-off value. At a cut-off of 11.9 of the high positive control serum (percentage positivity), the I-ELISA specificity was 100%, sensitivity 99.4%, and the Jouden index was 0.99.
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PMID:Preparation of recombinant African horse sickness virus VP7 antigen via a simple method and validation of a VP7-based indirect ELISA for the detection of group-specific IgG antibodies in horse sera. 1573 17

Between 2004 and 2006, 145 African horse sickness viruses (AHSV) were isolated from blood and organ samples submitted from South Africa to the Faculty of Veterinary Science, University of Pretoria. All nine serotypes were represented, with a range of 3-60 isolates per serotype. The RNA small segment 10 (S10) nucleotide sequences of these isolates were determined and the phylogeny investigated. AHSV, bluetongue virus (BTV) and equine encephalosis virus (EEV) all formed monophyletic groups and BTV was genetically closer to AHSV than EEV. This study confirmed the presence of three distinct S10 phylogenetic clades (alpha, beta and gamma). Some serotypes (6, 8 and 9 in alpha; 3 and 7 in beta; 2 in gamma) were restricted to a single clade, while other serotypes (1, 4 and 5) clustered into both the alpha and gamma clades. Strong purifying selection was evident and a constant molecular clock was inappropriate. The S10 gene is the second most variable gene of the AHSV genome and the use of S10 in molecular epidemiology was illustrated by an AHS outbreak in the Western Cape in 2004. It was shown that two separate AHSV were circulating in the area, even though AHSV serotype 1 was the only isolate from the outbreak. The small size of the gene (755-764 bp) and conserved terminal regions facilitate easy and quick sequencing. The establishment of an S10 sequence database is important for characterizing outbreaks of AHS. It will be an essential resource for elucidating the epidemiology of AHS.
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PMID:Molecular epidemiology of the African horse sickness virus S10 gene. 1842 Jul 93

African horse sickness virus serotype 9 (AHSV-9) has been known for some time to be circulating amongst equids in West Africa without causing any clinical disease in indigenous horse populations. Whether this is due to local breeds of horses being resistant to disease or whether the AHSV-9 strains circulating are avirulent is currently unknown. This study shows that the majority (96%) of horses and donkeys sampled across The Gambia were seropositive for AHS, despite most being unvaccinated and having no previous history of showing clinical signs of AHS. Most young horses (<3 years) were seropositive with neutralizing antibodies specific to AHSV-9. Eight young equids (<3 years) were positive for AHSV-9 by serotype-specific RT-PCR and live AHSV-9 was isolated from two of these horses. Sequence analysis revealed the presence of an AHSV-9 strain showing 100% identity to Seg-2 of the AHSV-9 reference strain, indicating that the virus circulating in The Gambia was highly likely to have been derived from a live-attenuated AHSV-9 vaccine strain.
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PMID:African horse sickness in The Gambia: circulation of a live-attenuated vaccine-derived strain. 2173 65

The study was conducted from June 2011 to May 2012 in central, northern and western parts of Ethiopia to investigate and identify circulating serotypes of African horse sickness virus (AHSV). The indigenous knowledge of equine owners about AHS in the study areas was assessed and also the retrospective data of AHS outbreaks for 2011 were analyzed. Whole blood samples were collected for virus isolation and serotyping from diseased horses and mules showing typical signs of the AHS. Virus isolation on Vero cell and detection of AHSV genomes using conventional RT-PCR were conducted. Further molecular characterization and serotyping were done on positive isolates. The questionnaire survey revealed that equine owners do recognize AHS clinically and have a local name that varies in different regions. From the 72 equine owners interviewed about their knowhow of AHS, 48 (66.7%) of respondents were not aware of AHS disease mode of transmission. The retrospective disease report data showed that a total of 208 outbreaks were reported and 3036 cases and 1167 deaths were recorded in 2011. AHS outbreaks were more frequently observed from September to December and the highest number of outbreaks was recorded in October. During the study period totally six outbreaks were investigated and a total of 62 horses and 10 mules were found sick and all the four forms of AHS were observed. Cardiac form accounted for 52.8%, followed by African horse sickness fever form 31.9%, pulmonary form 8.4% and mixed form 6.9%. AHSV-9 was the only serotype circulating in the outbreak areas.
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PMID:Outbreak investigation and molecular characterization of African horse sickness virus circulating in selected areas of Ethiopia. 2356 54

African horse sickness virus (AHSV) is an orbivirus, a member of the Reoviridae family. Nine different serotypes have been described so far. AHSV is vectored by Culicoides spp. to equids, causing high mortality, particularly in horses, with considerable economic impacts. For development of a safe attenuated vaccine, we previously established an efficient reverse genetics (RG) system to generate Entry Competent Replication-Abortive (ECRA) virus strains, for all nine serotypes and demonstrated the vaccine potential of these strains in type I interferon receptor (IFNAR)-knockout mice. Here, we evaluated the protective efficacies of these ECRA viruses in AHSV natural hosts. One monoserotype (ECRA.A4) vaccine and one multivalent cocktail (ECRA.A1/4/6/8) vaccine were tested in ponies and subsequently challenged with a virulent AHSV4. In contrast to control animals, all vaccinated ponies were protected and did not develop severe clinical symptoms of AHS. Furthermore, the multivalent cocktail vaccinated ponies produced neutralizing antibodies against all serotypes present in the cocktail, and a foal born during the trial was healthy and had no viremia. These results validate the suitability of these ECRA strains as a new generation of vaccines for AHSV.
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PMID:Protective efficacy of multivalent replication-abortive vaccine strains in horses against African horse sickness virus challenge. 2862 21

The aim of the study was to estimate and compare the distribution of Culicoides biting midges species at farms with different main hosts - cattle and horse. Culicoides spp. are known vectors of arboviruses including African horse sickness virus (AHSV), bluetongue virus (BTV) and Schmallenberg virus (SBV). The latter two have been already reported in Polish ruminants recently, while AHSV remains absent, however the risk of its emergence has been increasing in the recent years. In order to establish the activity of potential AHSV vector at vicinity of horses, an OVI midge trap has been placed at the horse stables in the southeastern Poland. Another trap has been placed 7 km away at the cattle farm. The collections were carried over the midge activity season from April until November 2016. The midge abundances at both sites were comparable with the total numbers of insects trapped of 43,153 and 34,829 at the cattle and horse farm, respectively. Midges belonging to C. obsoletus/scoticus complex were the dominant ones at both locations. The other most abundant species were C. punctatus and C. pulicaris, while the other ten species identified (C. chiopterus, C. deltus, C. dewulfi, C. fagineus, C. impunctatus, C. newsteadi, C. nubeculosus, C. parroti, C. riethi, C. stigma) accounted for less than 0.5%. The study has shown that the Orbivirus vectors are present at a high abundance at the Polish horse farm, what may be a helpful tool in the AHS risk assessment in the nonendemic part of Europe.
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PMID:Abundance and species composition of Culicoides spp. biting midges near cattle and horse in South-Eastern Poland. 2903 52


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