Publications

electron microscopic studies on equine encephalosis virus.		1973	4798882
the characterization of equine encephalosis virus and the development of genomic probes.	equine encephalosis virus (eev) is an orbivirus associated with a peracute illness of horses in southern africa. the virus has now been partially purified for the first time and characterized on a molecular level. the virion is composed of 10 dsrna segments and a protein capsid consisting of at least seven structural proteins that vary in mr from 36,000 to 120,000. partial clones of six of the dsrna segments of eev serotype cascara were obtained and analysed for possible use as serotype-specific ...	1989	2549180
characterization and cloning of the african horsesickness virus genome.	the dsrna profiles of all nine african horsesickness virus (ahsv) serotypes were compared by agarose gel electrophoresis and page. the agarose profiles were identical, but a unique profile was obtained for each of the nine serotypes by page. nine of the 10 dsrna genome segments of ahsv-3 were cloned and the clones were used in dot-spot and northern blot hybridization experiments to determine intra- and inter-serogroup nucleic acid similarities. segments 1, 3, 4, 5, 7 and 8 were highly conserved ...	1990	2324709
a comparison of different genomic probes in the detection of virus-specified rna in orbivirus-infected cells.	different 32p-labelled genomic probes of bluetongue virus (btv), epizootic haemorrhagic disease virus (ehdv) and equine encephalosis virus (eev) were compared with respect to the detection of virus-specified rna in infected cells. the probe derived from the genome segment that encodes nonstructural protein ns1 was found to be the most sensitive, detecting virus-specified rna in glutaraldehyde-fixed cells as early as 2-3 h p.i. this comparison was based on the observation that the ns1 gene probe ...	1991	1651948
group-reactive elisas for detecting antibodies to african horsesickness and equine encephalosis viruses in horse, donkey, and zebra sera.	group-reactive enzyme-linked immunosorbent assays (elisas) were developed to selectively detect antibodies to african horsesickness virus (ahsv) and equine encephalosis virus (eev), 2 orbiviruses that infect equids. in indirect elisa, guinea pig antisera to all known ahsv or eev serotypes recognized immobilized ahsv serotype 3 or eev cascara, respectively. antisera from naturally infected animals did not cross-react with their respective heterologous viruses. the elisa was used in parallel with ...	1993	8385502
the isolation and identification of potchefstroom virus: a new member of the equine encephalosis group of orbiviruses.	virus was isolated from the blood of horses (n = 5) showing fever and jaundice and was identified as equine encephalosis virus. in cross neutralisation tests, the isolates were shown to belong to a new serotype related to gamil, one of the 6 known serotypes of equine encephalosis virus. the name potchefstroom has been proposed for this new serotype.	1993	8176687
prevalence of antibodies against some equine viruses in zebra (zebra burchelli) in the kruger national park, 1991-1992.	the presence of antibodies against equine encephalosis virus (eev) and equid herpesvirus 1 and 4 in zebra in the kruger national park (knp) was demonstrated. the ability of zebra to maintain immunity against eev is illustrated by the appearance of neutralizing antibodies in most zebra foals within months of losing their maternal immunity. this occurs in every month of the year, even in winter. the high proportion of serologically positive foals in winter is ascribed to the presence of large numb ...	1993	7970572
detection of african horsesickness virus and discrimination between two equine orbivirus serogroups by reverse transcription polymerase chain reaction.	a reverse transcription polymerase chain reaction (rt-pcr), based on the gene encoding the ns2 protein of african horsesickness virus (ahsv), was developed for rapid serogroup-specific detection of ahsv. the specificity of rt-pcr products was confirmed by southern blot hybridization using a radioactively labelled cdna probe specific for the ns2 gene. this rt-pcr could discriminate between all known members of the ahsv and equine encephalosis virus serogroups. ahsv rna was detected in a sample re ...	1998	9629584
vector competence of selected south african culicoides species for the bryanston serotype of equine encephalosis virus.	equine encephalosis virus (eev) was recognized and described in the republic of south africa in 1967 and subsequent serological studies have shown this orbivirus to be both widespread and prevalent in southern africa. in the present study it was shown that wild-caught culicoides (avaritia) imicola kieffer (diptera: ceratopogonidae) can become infected with and permit the replication of the bryanston serotype of eev following membrane-feeding on infective blood containing 5.0 log10 plaque-forming ...	1999	10608228
the use of chicken igy in a double antibody sandwich elisa for detecting african horsesickness virus.	an indirect sandwich elisa that can detect as little as 8 ng of african horsesickness virus (ahsv) was developed. viral antigen was captured from suspension using an immobilized monoclonal antibody specific for an epitope on vp7, a protein that is a major constituent of the virus core. egg-yolk derived chicken igy directed against ahsv (serotype 3) was used as the secondary antibody. since igy and mouse igg do not cross-react serologically, the secondary antibody was not labelled, but was instea ...	1999	10396758
development of probes for typing african horsesickness virus isolates using a complete set of cloned vp2-genes.	a set of cloned full-length vp2-genes from the reference strain of each of the nine serotypes of african horsesickness virus (ahsv) was used to develop probes for typing ahsv isolates. the vp2-gene probes hybridised serotype-specific to purified viral dsrna from its corresponding serotype. no cross-hybridisation was observed between the different ahsv serotypes or with rna from equine encephalosis virus or bluetongue virus (btv) which are related viruses within the genus orbivirus that co-circul ...	2000	10960701
a comparison of the vector competence of the biting midges, culicoides (avaritia) bolitinos and c. (a.) imicola, for the bryanston serotype of equine encephalosis virus.	equine encephalosis virus (eev) is widespread and prevalent in southern africa. in this study, the oral susceptibility of culicoides (avaritia) imicola kieffer (diptera: ceratopogonidae) to eev was confirmed. in addition, c. (a.) bolitinos meiswinkel, collected in the high-lying eastern free state, south africa, was systemically infected with the bryanston serotype of eev after feeding through a membrane on artificially infected equine blood containing 4.7 log10 pfu/ml of eev. the mean infectivi ...	2002	12510889
the classification of seven serotypes of equine encephalosis virus and the prevalence of homologous antibody in horses in south africa.	selected isolates of equine encephalosis virus were shown to have comparable viral protein profiles and to represent seven distinct serotypes, based on cross-neutralization tests. serotype-specific virus-neutralizing antibody in serum samples from horses confirmed the widespread occurrence of infection. the distribution and prevalence of individual serotypes however, varied considerably. localised foci with an increased seasonal seroconversion in groups of horses to a specific serotype and the d ...	2002	12092781
a group-specific, indirect sandwich elisa for the detection of equine encephalosis virus antigen.	a polyclonal antibody-based, group-specific, indirect, sandwich elisa (s-elisa) for the detection of equine encephalosis virus (eev) antigen was developed. purified eev particles were titrated in the s-elisa and the limit of detection was determined to be approximately 9.0 ng of antigen/ml (0.45 ng/well). positive s-elisa reactions were recorded with seven serologically distinct eev serotypes. no cross-reactions were recorded with other arboviruses including african horse sickness virus (ahsv) s ...	2003	12951221
variation in the ns3 gene and protein in south african isolates of bluetongue and equine encephalosis viruses.	bluetongue virus (btv) and equine encephalosis virus (eev) are agriculturally important orbiviruses transmitted by biting midges of the genus culicoides. the smallest viral genome segment, s10, encodes two small nonstructural proteins, ns3 and ns3a, which mediate the release of virus particles from infected cells and may subsequently influence the natural dispersion of these viruses. the ns3 gene and protein sequences of south african isolates of these viruses were determined, analysed and compa ...	2003	12604809
vector competence of culicoides species and the seroprevalence of homologous neutralizing antibody in horses for six serotypes of equine encephalosis virus (eev) in south africa.	field-collected culicoides species (diptera: ceratopogonidae) were fed on horse blood-virus mixtures containing one of the six serotypes of equine encephalosis virus (eev1 to eev6). the virus mean titres in the bloodmeals varied between 6.1 and 7.0 log10tcid50/ml. of 19 culicoides species assayed after 10 days extrinsic incubation at 23.5 degrees c, five yielded the challenge virus, namely culicoides (avaritia) imicola kieffer (eev1-6), c. (a.) bolitinos meiswinkel (eev1, 2, 4, 6), c. (meijerehe ...	2004	15642007
a comparison of different orbivirus proteins that could affect virulence and pathogenesis.	the factors that determine the virulence and pathogenesis characteristics of bluetongue virus (btv), african horse sickness virus (ahsv) and other orbiviruses are not well known. with respect to the viral proteins that are expected to play a role it may be assumed that proteins, such as the outer capsid proteins vp2 and vp5, that are involved in the attachment of virus particles to target cells and influence replication efficiency are particularly important. equally important are viral proteins ...	2004	20422564
investigations on outbreaks of african horse sickness in the surveillance zone in south africa.	confirmed outbreaks of african horse sickness (ahs) occurred in the surveillance zone of the western cape in 1999 and 2004, both of which led to a two-year suspension on the export of horses. light trap surveys in the outbreak areas showed that known vector competent culicoides species, notably c. imicola, were abundant and present in numbers equal to those in the traditional ahs endemic areas. isolations of ahs virus serotypes 1 and 7, equine encephalosis virus, and bluetongue virus from field- ...	2006	17361773
a duplex rt-pcr assay for detection of genome segment 7 (vp7 gene) from 24 btv serotypes.	since 1998, six distinct serotypes of bluetongue virus (btv) have invaded southern and central europe, persisting in some regions for up to 6 years and resulting in the deaths of >1.8 million sheep. rapid and reliable methods of virus detection and identification play an essential part in our fight against bluetongue disease (bt). we have therefore developed and evaluated a duplex, one-step rt-pcr assay that detects genome segment 7 (encoding the major serogroup (virus-species) specific antigen ...	2007	17241676
prevalence of serotype specific antibody to equine encephalosis virus in thoroughbred yearlings in south africa (1999-2004).	cohorts of yearlings were sampled over a period of 6 years in a retrospective serological survey to establish the annual prevalence of serotype specific antibody to equine encephalosis virus on thoroughbred stud farms distributed within defined geographical regions of south africa. seasonal seroprevalence varied between 3.6% and 34.7%, revealing both single and multiple serotype infections in an individual yearling. during the course of this study serotypes 1 and 6 were most frequently and exten ...	2008	18788209
molecular epidemiology of the african horse sickness virus s10 gene.	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 ...	2008	18420793
equine encephalosis virus in israel.		2009	19744233
improved strategies for sequence-independent amplification and sequencing of viral double-stranded rna genomes.	this paper reports significant improvements in the efficacy of sequence-independent amplification and quality of sequencing of viruses with segmented double-stranded rna (dsrna) genomes. we demonstrate that most remaining bottlenecks in dsrna virus genome characterization have now been eliminated. both the amplification and sequencing technologies used require no previous sequence knowledge of the viral dsrna, there is no longer a need to separate genome segments or amplicons and the sequence-de ...	2009	19264638
re-emergence of bluetongue, african horse sickness, and other orbivirus diseases.	arthropod-transmitted viruses (arboviruses) are important causes of disease in humans and animals, and it is proposed that climate change will increase the distribution and severity of arboviral diseases. orbiviruses are the cause of important and apparently emerging arboviral diseases of livestock, including bluetongue virus (btv), african horse sickness virus (ahsv), equine encephalosis virus (eev), and epizootic hemorrhagic disease virus (ehdv) that are all transmitted by haematophagous culic ...	2010	20167199
Equine encephalosis virus: evidence for circulation beyond southern Africa.	SUMMARYPrior to the recent outbreak of equine encephalosis in Israel in 2009, equine encephalosis virus (EEV) had only been isolated from equids in South Africa. In this study we show the first evidence for the circulation of EEV beyond South Africa in Ethiopia, Ghana and The Gambia, indicating that EEV is likely to be freely circulating and endemic in East and West Africa. Sequence analysis revealed that the EEV isolate circulating in The Gambia was closely related to an EEV isolate that was is ...	2011	22166372
serotype specific primers and gel-based rt-pcr assays for 'typing' african horse sickness virus: identification of strains from africa.	african horse sickness is a devastating, transboundary animal disease, that is 'listed' by the office international des epizooties (oie). although attenuated, inactivated and subunit vaccines have been developed for african horse sickness virus (ahsv), these are serotype-specific and their effective deployment therefore relies on rapid and reliable identification of virus type. ahsv serotype is controlled by the specificity of interactions between neutralising antibodies, and components of the o ...	2011	22028787
a competitive elisa for the detection of group-specific antibody to equine encephalosis virus.	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 est ...	2011	21458496
isolation and phylogenetic grouping of equine encephalosis virus in israel.	during 2008-2009 in israel, equine encephalosis virus (eev) caused febrile outbreaks in horses. phylogenetic analysis of segment 10 of the virus strains showed that they form a new cluster; analysis of segment 2 showed ≈92% sequence identity to eev-3, the reference isolate. thus, the source of this emerging eev remains uncertain.	2011	22000361
sustained high-throughput polymerase chain reaction diagnostics during the european epidemic of bluetongue virus serotype 8.	a real-time reverse transcription polymerase chain reaction assay (pcr test) based on genome segment 10 of bluetongue virus (btv) was developed. the pcr test consists of robotized viral rna isolation from blood samples and an all-in-one method including initial denaturation of genomic double-stranded rna, reverse transcription polymerase chain reaction (rt-pcr), and real-time detection and analysis. reference strains of the 24 recognized btv serotypes, isolates from different years, and geograph ...	2012	22529113
serotype- and serogroup-specific detection of african horsesickness virus using phage displayed chicken scfvs for indirect double antibody sandwich elisas.	there is an ongoing need for standardized, easily renewable immunoreagents for detecting african horsesickness virus (ahsv). two phage displayed single-chain variable fragment (scfv) antibodies, selected from a semi-synthetic chicken antibody library, were used to develop double antibody sandwich enzyme-linked immunosorbent assays (das-elisas) to detect ahsv. in the das-elisas, the scfv previously selected with directly immobilized ahsv-3 functioned as a serotype-specific reagent that recognized ...	2013	23388433
evidence for the circulation of equine encephalosis virus in israel since 2001.	equine encephalosis virus (eev) distribution was thought to be limited to southern africa until 2008 when we reported eev in israel. it was then assumed that the clinical presentation resembled the initial incursion in israel. to investigate further we conducted a retrospective analysis of equine sera, which had been collected for diagnosis of other suspected diseases, via serum neutralisation test. the data demonstrated that eev was circulating as early as 2001 with incidence ranging from 20-10 ...	2013	23950952
correction: evidence for the circulation of equine encephalosis virus in israel since 2001.	[this corrects the article on p. e70532 in vol. 8.].	2013	24116260
pathology of fatal lineage 1 and 2 west nile virus infections in horses in south africa.	since 2007, west nile virus (wnv) has been reported in south african horses, causing severe neurological signs. all cases were of lineage 2, except for one case that clustered with lineage 1 viruses. in the present study, gross and microscopic lesions of six south african lineage 2-infected horses and the one lineage 1 case are described. diagnoses were confirmed by real-time reverse-transcriptase polymerase chain reaction (rt-pcr) of central nervous system (cns) tissue and one by rt-pcr of a br ...	2014	25686260
development of a real time polymerase chain reaction assay for equine encephalosis virus.	equine encephalosis virus (eev) is the cause of equine encephalosis. the disease is similar to mild forms of african horse sickness (ahs) and the two diseases are easily confused. laboratory identification and serotyping of eev is based on viral isolation in bhk-21 cells and a viral plaque inhibition neutralisation test. these procedures are time-consuming and therefore a more rapid diagnostic assay for eev that can distinguish eev from african horse sickness virus (ahsv) infections was develope ...	2014	24161811
zoonotic and emerging orbivirus infections.	many novel emerging orbiviruses have been isolated in the past 15 years. important viruses include peruvian horse sickness virus (phsv) and yunnan orbivirus (yuov), pathogens of equids which were originally isolated almost simultaneously from 1997 to 1999 in the people's republic of china, australia and peru. yuov has also been isolated from cattle, sheep and a dog. the isolation of yuovfrom a dog is not the first case of an orbivirus being isolated from a carnivore. bluetongue virus and african ...	2015	26601440
quantitative analysis of the probability of introducing equine encephalosis virus (eev) into the netherlands.	equine encephalosis is a midge-borne viral disease of equines caused by equine encephalosis virus (eev, orbivirus, reoviridae), and closely related to african horse sickness virus (ahsv). eev and ahsv share common vectors and show similar transmission patterns. until now eev has caused outbreaks in africa and israel. this study aimed to provide insight in the probability of an eev outbreak in the netherlands caused by infected vectors or hosts, the contribution of potential source areas (risk re ...	2016	27544251
seroprevalence and risk factor analysis for exposure to equine encephalosis virus in israel, palestine and jordan.	equine encephalosis virus (eev) is an orbivirus transmitted by culicoides species. most infected horses show mild clinical signs and mortality is usually very low. eev is closely related and similarly transmitted to other, more pathogenic and economically important, orbiviruses such as african horse sickness virus (ahsv), bluetongue virus (btv) and epizootic haemorrhagic disease viruses (ehdv), and may serve as an indicator for possible transmission of the latter. israel has been reported to be ...	2017	28713576
the sero-prevalence and sero-incidence of african horse sickness and equine encephalosis in selected horse and donkey populations in zimbabwe.	sentinel herds and samples submitted by private equine practitioners were used to determine the sero-prevalence and sero-incidence of african horse sickness virus (ahsv) and equine encephalosis virus (eev) in horse and donkey populations in the highveld region of zimbabwe. the sero-prevalence and sero-incidence of antibodies against these viruses were determined using the competitive enzyme-linked immunosorbent assay (elisa) for the detection of serum antibodies. in donkeys, the median sero-prev ...	2017	28582979
analysis of the association of climate, weather and herd immunity with the spread of equine encephalosis virus in horses in israel.	it is claimed that the distribution of culicoides-borne viruses is highly influenced by climate. equine encephalosis virus (eev) is a culicoides-borne orbivirus which affects horses and was recently found to be endemic in israel. to test whether climate is a crucial factor in the geographical distribution of eev, we collected blood samples from horses in israel during the years 2002, 2007 and 2010 and tested them for the abundance of antibodies to eev. samples were also collected in 2011 from ho ...	2017	26392206