Research Articles (Equine Research Centre)

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Review of Pseudomonas aeruginosa and Klebsiella pneumoniae as venereal pathogens in horses
(Wiley, 2024) Scholtz, Melanie; Guthrie, Alan John; Newton, Richard; Schulman, M.L. (Martin)
Three bacteria extensively acknowledged as venereal pathogens with the potential to induce endometritis include Taylorella equigenitalis, the causative agent of contagious equine metritis (CEM), specific strains of Pseudomonas aeruginosa, and certain capsule types of Klebsiella pneumoniae. The United Kingdom's Horserace Betting Levy Board recommends pre-breeding screening for these bacteria in their International Codes of Practice and >20 000 samples are tested per annum in the United Kingdom alone. While the pathogenesis and regulatory importance of CEM are well established, an evaluation of the literature pertaining to venereal transmission of P. aeruginosa and K. pneumoniae was lacking. The aim of this review was to evaluate published literature and determine the significance of P. aeruginosa and K. pneumoniae as venereal pathogens in horses. Literature definitively demonstrating venereal transmission was not available. Instead, application of molecular typing methods suggested that common environmental sources of contamination, such as water, or fomites be considered as modes of transmission. The presence of organisms with pathogenic potential on a horse's external genitalia did not predict venereal transmission with resultant endometritis and reduced fertility. These findings may prompt further investigation using molecular technologies to confirm or exclude venereal spread and investigation of alternative mechanisms of transmission are indicated.
Bluetongue virus infection in farm dogs exposed to an infected sheep flock in South Africa
(Wiley, 2024-07) Hanekom, Josef; Ebersohn, Karen; Penzhorn, Lisa; Quan, Melvyn; Leisewitz, Andrew L.; Guthrie, Alan John; Fosgate, Geoffrey Theodore; joe.hanekom@up.ac.za
In 2021, a pregnant Rottweiler dog living on a sheep farm was diagnosed with clinical bluetongue (BT) infection. This study reports on the investigation of this farm where bluetongue virus (BTV) infection was diagnosed in this atypical host species. Samples were collected during farm visits 14, 28, 60, and 89 days after the onset of clinical signs in the pregnant Rottweiler. Blood was collected from all farm dogs (n = 6) and tested for BTV genome using a reverse-transcriptase quantitative PCR (RT-qPCR) assay and BTV antibodies with the competitive ELISA (cELISA) and dogs positive by RT-qPCR were further tested using virus neutralization (VN) serological testing. Blood was also collected from 16 sick sheep and tested using RT-qPCR. Midges were trapped on the study farm using an Onderstepoort UV light trap placed above a sheep pen for 36 hr at the first farm (14 days) visit. Parous/gravid midges were tested by BTV RT-qPCR in batches of up to 200 midges per species. Blood-fed midges (n = 308) were tested using a PCR species probe (KAPA Multiplex Master Mix) to identify the host species on which the midge had fed. Three dogs (n = 3/6) had detectable BTV RNA with RT-qPCR and high VN antibody titers to BTV. All RT-qPCR-positive dogs and one additional dog tested cELISA seropositive (n = 4/6). Bluetongue virus RNA was detected in 5/16 sheep tested. The most abundant midge species was Culicoides imicola (99.3%) and BTV was only detected in this species (n = 3/4 batches of 200 parous midges). Dog blood was not detected in any blood-fed midges tested. The occurrence of natural BT viraemia in exposed dogs creates a potential risk of BTV entry into BT-free countries through dog importation. It remains unclear whether BT viremia in dogs is capable of onward transmission.
The seroprevalence of African horse sickness virus, and risk factors to exposure, in domestic dogs in Tshwane, South Africa
(Elsevier, 2023-04) Hanekom, Josef Derek; Lubisi, Baratang Alison; Leisewitz, Andrew L.; Guthrie, Alan John; Fosgate, Geoffrey Theodore; joe.hanekom@up.ac.za
Dogs are the only non-equid species to develop the fatal form of African horse sickness (AHS). Research conducted in 2013 questioned the long-held belief that naturally occurring cases of AHS in dogs were contracted exclusively through the ingestion of contaminated horse meat. Culicoides midges, the vector of AHS virus (AHSV) for horses, have an aversion to dog blood meals and dogs were believed to be dead-end or incidental hosts. More recently, dog mortalities have occurred in the absence of horse meat consumption and vector transmission has been suspected. The current study is a retrospective serological survey of AHSV exposure in dogs from an endemic area. Dog sera collected from dogs (n = 366) living in the city of Tshwane, Gauteng Province, South Africa, were randomly selected from a biobank at a veterinary teaching hospital, corresponding to the years 2014–2019. The study used a laboratory in-house indirect recombinant VP7 antigen-based enzyme-linked immunosorbent assay (iELISA) with a test cut-off calculated from AHSV exposure-free dog sera (n = 32). Study AHSV seroprevalence was 6 % (22/366) with an estimated true prevalence of 4.1 % (95 % confidence interval (CI) = 1.3–8.1 %). Incidence was estimated for dogs with multiple serological results with seroconversion occurring at a rate of 2.3 seroconversions per 10 dog years at risk (95 % CI = 0.6–6.2). A subsection of the study sera was tested with AHSV viral neutralisation test (VN) (n = 42) for serotype determination. Antibodies to AHSV serotype 6 were most prevalent (90 %) in VN seropositive dogs (n = 20) with most dogs seemingly subclinically infected (>95 %). Seroprevalence descriptively varied by year and identified risk factors were annual rainfall > 754 mm (odds ratio (OR) = 5.76; 95 % CI = 2.22 – 14.95; p < 0.001), medium human population densities, 783–1663 people/km2 (OR = 7.14; 95 % CI = 1.39 – 36.73; p = 0.019) and 1664–2029 people/km2 (OR = 6.74; 95 % CI = 1.40 – 32.56; p = 0.018), and the month of March (OR = 5.12; 95 % CI = 1.41 – 18.61; p = 0.013). All identified risk factors were consistent with midge-borne transmission to dogs. The relatively high seroprevalence and seroconversion rates suggest frequent exposure of dogs to AHSV and indicates the need to investigate the role dogs might play in the overall epidemiology and transmission of AHSV.
Predictors of foaling outcomes in barren and maiden thoroughbred mares in South Africa
(Medpharm Publications, 2022) Scholtz, M.; Guthrie, Alan John; Fosgate, Geoffrey Theodore; Schulman, M.L. (Martin); melanie.scholtz@up.ac.za
Population demographics and reproductive performance of Thoroughbred populations have been described, but the most recent assessment of the South African Thoroughbred population was reported two decades ago. Objectives of this study were to report demographic data for selected Thoroughbred breeding populations and to analyse selected mare-level variables in association with foaling outcomes, as predictors of reproductive performance. The National Horseracing Authority of Southern Africa's stud health scheme requires annual screening of Thoroughbred stallions, maiden and barren mares for venereal pathogens prior to breeding. In 2018 and 2019, 1 065 and 1 207 horses were sampled, respectively. Demographic data were sourced from laboratory sample submission forms that accompanied samples and supplemented by data gathered from the annual Thoroughbred foal identification programme. Univariate analysis of candidate predictors of successful foaling outcomes was performed followed by assessment in a multivariable model. Median ages of mares and stallions tested in 2018 and 2019 were nine and 11 years, respectively. Nearly twice the number of barren compared to maiden mares were tested in each year, and failure to conceive was the most common reported reason for classification as barren. Of mares tested in 2018 and 2019, 68.1% (95% CI 65.1-70.9) and 63.3% (95% CI 60.4-66.1), respectively, subsequently produced foals that were presented for identification. Mare age, rather than reproductive status, was a significant predictor of having a foal presented for identification. In conclusion, novel demographic data were described for South African Thoroughbred populations. Seasonal foaling rate as the selected measure of reproductive performance for sampled mares ranged from 63.3% to 68.1% and declined with increasing mare age.
Clinical course of infection and cross-species detection of equine parvovirus-hepatitis
(MDPI, 2021-08) Reinecke, Birthe; Klohn, Mara; Bruggemann, Yannick; Kinast, Volker; Todt, Daniel; Stang, Alexander; Badenhorst, Marcha; Koeppel, Katja Natalie; Guthrie, Alan John; Groner, Ursula; Puff, Christina; De le Roi, Madeleine; Baumgärtner, Wolfgang; Cavalleri, Jessika-M. V.; Steinmann, Eike
Since its first discovery by Arnold Theiler in 1918, serum hepatitis also known as Theiler’s disease has been reported worldwide, causing idiopathic acute hepatitis and liver failure in horses. Recent studies have suggested a novel parvovirus, named equine parvovirus hepatitis (EqPV-H), to be associated with Theiler’s disease. Despite the severity and potential fatality of EqPV-H infection, little is known about the possibility of developing chronic infections and putative cross-species infection of equine sister species. In the present longitudinal study, we employed qPCR analysis, serology, and biochemical testing as well as pathology examination of liver biopsies and sequence analysis to investigate potential chronic EqPV-H infection in an isolated study cohort of in total 124 horses from Germany over five years (2013–2018). Importantly, our data suggest that EqPV-H viremia can become chronic in infected horses that do not show biochemical and pathological signs of liver disease. Phylogenetic analysis by maximum likelihood model also confirms high sequence similarity and nucleotide conservation of the multidomain nuclear phosphoprotein NS1 sequences from equine serum samples collected between 2013–2018. Moreover, by examining human, zebra, and donkey sera for the presence of EqPV-H DNA and VP1 capsid protein antibodies, we found evidence for cross-species infection in donkey, but not to human and zebra. In conclusion, this study provides proof for the occurrence of persistent EqPV-H infection in asymptomatic horses and cross-species EqPV-H detection in donkeys.
Complete genome sequences of virus strains isolated from bottle A of the South African live attenuated bluetongue virus vaccine
(American Society for Microbiology, 2020-05-28) Coetzee, Peter; Guthrie, Alan John; Ebersohn, Karen; Maclachlan, James N.; Ismail, Arshad; Van Schalkwyk, Antoinette; Venter, Estelle Hildegard
This is a report of the complete genome sequences of plaque-selected isolates of five virus strains included in bottle A of the South African Onderstepoort Biological Products commercial live attenuated bluetongue virus vaccine.
Evaluating African horse sickness virus in horses and field-caught Culicoides biting midges on the East Rand, Gauteng Province, South Africa
(Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, 2019) Craig, Anthony Francis; Packer, G.C. (Glenn); Guthrie, Alan John; Venter, Estelle Hildegard
A prospective study was undertaken during 2013 and 2014, to determine the prevalence of African horse sickness virus (AHSV) in Culicoides midges and the incidence of infection caused by the virus in 28 vaccinated resident horses on two equine establishments on the East Rand, Gauteng Province, South Africa. Field caught Culicoides midges together with whole blood samples from participating horses were collected every two weeks at each establishment. Culicoides midges and blood samples were tested for the presence of AHSV RNA by real-time quantitative reverse transcription polymerase chain reaction. Nine immunised horses became infected with AHSV during the study period, although infections were subclinical. African horse sickness virus was also identified from a field-collected midge pool. The observations recapitulate previously published data in another setting, where further investigation is warranted to determine what role subclinical infection plays in the diseases epidemiology
Direct culture–independent sequence typing of Taylorella equigenitalis obtained from genital swabs and frozen semen samples from South African horses
(Sage, 2019-09) May, Catherine Edith; Guthrie, Alan John; Schulman, M.L. (Martin); kate.may@up.ac.za
We report herein the use of crude extracts obtained from samples of Taylorella equigenitalis–infected horses for the purpose of multi-locus sequence typing (MLST). Samples (n = 36) were collected from horses in South Africa from 1996 to 2017: 34 from genital swabs (stored at −20°C for 2–3 y) and 2 from cryopreserved raw semen aliquots (stored at −70°C for 18 y) prior to assay. The MLST assay showed a single sequence type (ST), designated ST4, that supported a point introduction and thus a common source for the South African outbreak of contagious equine metritis.
A field investigation of an African horse sickness outbreak in the controlled area of South Africa in 2016
(Wiley, 2019-03) Grewar, John Duncan; Weyer, Camilla Theresa; Venter, Gert Johannes; Van Helden, Lesley Susan; Burger, Phillippa; Guthrie, Alan John; Coetzee, Peter; Labuschagne, Karien; Buhrmann, Gary; Parker, Beverley Joan; Thompson, P.N. (Peter N.)
An outbreak of African horse sickness (AHS) caused by AHS virus type 1 occurred within the South African AHS surveillance zone during April and May 2016. The index case was detected by a private veterinarian through passive surveillance. There were 21 cases in total, which is relatively low compared to case totals during prior AHS outbreaks in the same region (and of the same AHS virus type) in 2004, 2011 and 2014. The affected proportion of horses on affected properties was 0.07 (95% CI 0.04, 0.11). Weather conditions were conducive to high midge activity immediately prior to the outbreak but midge numbers decreased rapidly with the advent of winter. The outbreak was localized, with 18 of the 21 cases occurring within 8 km of the index property and the three remaining cases on two properties within 21 km of the index property, with direction of spread consistent with wind‐borne dispersion of infected midges. Control measures included implementation of a containment zone with movement restrictions on equids. The outbreak was attributed to a reversion to virulence of a live attenuated vaccine used extensively in South Africa. Outbreaks in the AHS control zones have a major detrimental impact on the direct export of horses from South Africa, notably to the European Union.
First detection and frequent occurrence of Equine Hepacivirus in horses on the African continent
(Elsevier, 2018-09) Badenhorst, Marcha; Tegtmeyer, Birthe; Todt, Daniel; Guthrie, Alan John; Feige, Karsten; Campe, Amely; Steinmann Eike; Cavalleri, J.M.V. (Jessika)
Since the discovery of equine hepacivirus (EqHV) in 2011, the virus has been detected in horse populations from more than twelve countries across five continents. EqHV seroprevalence has been reported to be as high as 61.8% and EqHV ribonucleic acid (RNA) prevalence to range between 0.9% and 34.1%. Molecular and serological indications of EqHV infection have never been reported in equids on the African continent. Therefore, investigation of EqHV prevalence in South African horses and subsequent viral genetic characterization contribute to a better understanding of the global epidemiology of this virus. In a cross-sectional study, serum samples from 454 Thoroughbred foals (aged 58–183 days) were analysed for anti-EqHV non-structural protein 3 (NS3)-specific antibodies (abs) with a luciferase immunoprecipitation system (LIPS) and for EqHV RNA by quantitative real-time polymerase chain reaction (qRT-PCR). Farms of origin (n = 26) were situated in South Africa’s Western Cape Province. The associations between EqHV infection state and farm of origin, foal gender and foal age were subsequently described. Furthermore, nested PCRs were performed on parts of the 5′UTR, NS3 and NS5B genes of 17 samples. Samples were sequenced and phylogenetic analyses were conducted. The population’s seroprevalence was 83.70% and RNA was detected in 7.93% of samples. Increasing foal age was associated with decreasing ab prevalence and increasing prevalence of EqHV RNA. Sequences from South African EqHV strains did not show in-depth clustering with published sequences of EqHV isolates from particular continents. In conclusion, EqHV is present in the South African Thoroughbred population and appears more prevalent than reported in other horse populations worldwide.
A serosurvey of bluetongue and epizootic haemorrhagic disease in a convenience sample of sheep and cattle herds in Zimbabwe
(AOSIS OpenJournals, 2017-11-14) Gordon, Stuart J.G.; Bolwell, Charlotte; Rogers, Chris W.; Musuka, Godfrey; Kelly, Patrick; Guthrie, Alan John; Mellor, Philip S.; Chris Hamblin
A convenience sample of sheep and cattle herds around the cities of Harare, Kwekwe and Bulawayo, located in the Highveld region of Zimbabwe, was used to estimate the seroprevalence and sero-incidence of bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) antibodies. A competitive enzyme-linked immunosorbent assay was used to identify serum antibodies against BTV and EHDV across three rainy seasons. The median sero-prevalence of BTV and EHDV antibodies in cattle was 62% (interquartile range [IQR]: 30–89) and 56% (IQR: 5–77), respectively. In sheep, the median sero-prevalence of BTV and EHDV was 41% (IQR: 19–63) and 0% (IQR: 0–21), respectively. Median sero-incidences of BTV and EHDV antibodies in cattle of 43% (IQR: 22–67) and 27% (IQR: 9–57) respectively were recorded. The median sero-incidence of BTV in sheep was 14% (IQR: 6–23). Based on these preliminary findings, animal health workers in Zimbabwe should continue to monitor the exposure rates of cattle and sheep to BTV and consider the possibility of strains emerging with increased pathogenicity. There are no previous published reports of antibodies against EHDV in Zimbabwe so the possibility of epizootic haemorrhagic disease existing in domestic livestock should now be considered by Zimbabwean animal health officials. Seroconversions to BTV and EHDV occurred predominantly at the end of each rainy season (March and April), which generally corresponds to high numbers of the Culicoides vectors. BTV isolations were made from three individual cows in two of the sentinel herds and all three were identified as serotype 3. This is the first time BTV serotype 3 has been recorded in Zimbabwe, although its presence in neighbouring South Africa is well documented.
Friends and family : a software program for identification of unrelated individuals from molecular marker data
(Wiley, 2017-11) De Jager, G.J. (Deon); Swarts, Petrus; Harper, Cindy Kim; Bloomer, Paulette
The identification of related and unrelated individuals from molecular marker data is often difficult, particularly when no pedigree information is available and the data set is large. High levels of relatedness or inbreeding can influence genotype frequencies and thus genetic marker evaluation, as well as the accurate inference of hidden genetic structure. Identification of related and unrelated individuals is also important in breeding programmes, to inform decisions about breeding pairs and translocations. We present Friends and Family, a Windows executable program with a graphical user interface that identifies unrelated individuals from a pairwise relatedness matrix or table generated in programs such as coancestry and genalex. Friends and Family outputs a list of samples that are all unrelated to each other, based on a user‐defined relatedness cut‐off value. This unrelated data set can be used in downstream analyses, such as marker evaluation or inference of genetic structure. The results can be compared to that of the full data set to determine the effect related individuals have on the analyses. We demonstrate one of the applications of the program: how the removal of related individuals altered the Hardy–Weinberg equilibrium test outcome for microsatellite markers in an empirical data set.
The effect of alphacypermethrin-treated mesh protection against African horse sickness virus vectors on jet stall microclimate, clinical variables and faecal glucocorticoid metabolites of horses
(BioMed Central, 2017-09-09) Page, Patrick Collin; Ganswindt, Andre; Schoeman, Johan P.; Venter, Gert Johannes; Guthrie, Alan John
BACKGROUND : African horse sickness (AHS) is of importance to health and international trade in horses worldwide. During export from and transit through AHS endemic countries or zones, physical and chemical measures to protect horses from the vectors of AHS virus (AHSV) are recommended by the World Organization for Animal Health. Protection of containerized air transport systems for horses (jet stalls) with alphacypermethrin insecticidetreated high density polyethylene mesh is effective in reducing the Culicoides midge vector attack rate. In order to determine the effect of this mesh on jet stall ventilation and horse welfare under temperate climatic conditions, jet stall microclimate, clinical variables and faecal glucocorticoid metabolite (FGM) levels of 12 horses were monitored during overnight housing in either a treated or untreated stall in two blocks of a 2 × 3 randomized crossover design. RESULTS : Temperature difference between the treated stall and outside was significantly higher than the difference between the untreated stall and outside at 1/15 time points only (P = 0.045, r = 0.70). Relative humidity (RH) difference between the treated stall and outside did not differ from the untreated stall and outside. Temperature and RH in the treated stall were highly and significantly correlated with outside temperature (r = 0.96, P < 0.001) and RH (r = 0.95, P < 0.001), respectively. No significant differences were detected between rectal temperatures, pulse and respiratory rates of horses in the treated stall compared to the untreated stall. Mean FGM concentrations for horses housed in the treated stall peaked earlier (24 h) and at a higher concentration than horses housed in the untreated stall (48 h), but were not significantly different from baseline. No significant difference was detected in FGM concentrations when the treated and untreated stall groups were compared at individual time points up to 72 h after exiting the jet stall. CONCLUSIONS : Alphacypermethrin-treated HDPE mesh could be used under temperate climatic conditions to protect horses in jet stalls against AHSV vectors, without compromising jet stall microclimate and horse welfare.
Immunogenicity of plant-produced African horse sickness virus-like particles : implications for a novel vaccine
(Wiley, 2018-02) Dennis, Susan J.; Meyers, Ann E.; Guthrie, Alan John; Hitzeroth, Inga I.; Rybicki, Edward P.
African horse sickness (AHS) is a debilitating and often fatal viral disease affecting horses in much of Africa, caused by the dsRNA orbivirus African horse sickness virus (AHSV). Vaccination remains the single most effective weapon in combatting AHS, as there is no treatment for the disease apart from good animal husbandry. However, the only commercially available vaccine is a liveattenuated version of the virus (LAV). The threat of outbreaks of the disease outside its endemic region and the fact that the LAV is not licensed for use elsewhere in the world, have spurred attempts to develop an alternative safer, yet cost-effective recombinant vaccine. Here, we report the plant-based production of a virus-like particle (VLP) AHSV serotype five candidate vaccine by Agrobacterium tumefaciens-mediated transient expression of all four capsid proteins in Nicotiana benthamiana using the cowpea mosaic virus-based HyperTrans (CPMV-HT) and associated pEAQ plant expression vector system. The production process is fast and simple, scalable, economically viable, and most importantly, guinea pig antiserum raised against the vaccine was shown to neutralize live virus in cell-based assays. To our knowledge, this is the first report of AHSV VLPs produced in plants, which has important implications for the containment of, and fight against the spread of, this deadly disease.
The sero-prevalence and sero-incidence of African horse sickness and equine encephalosis in selected horse and donkey populations in Zimbabwe
(AOSIS OpenJournals, 2017-05-10) Gordon, Stuart J.G.; Bolwell, Charlotte; Rogers, Chris W.; Musuka, Godfrey; Kelly, Patrick; Guthrie, Alan John; Mellor, Philip S.; Hamblin, Christopher
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-prevalence of AHSV antibodies, across the three rainy seasons under study, was 75% (inter quartile range [IQR] 67–83), with a seasonal median sero-incidence of 45% (IQR 40–63). In horses, the median sero-prevalence of EEV antibodies was 63% (IQR 21–73), with a median seasonal sero-incidence of 10.5% (IQR 10–14), while in donkeys the median sero-prevalence of EEV antibodies was 80% (IQR 67–90), with a median seasonal sero-incidence of 50% (IQR 40–60). This study highlighted the significant levels of exposure of donkeys to AHSV and horses and donkeys to EEV in Zimbabwe despite equine encephalosis remaining unreported by Zimbabwean veterinarians to date. Most seroconversions in sentinel herd animals to AHSV and EEV occurred towards the end of the rainy season in March, April and May corresponding to the time of the year when the Culicoides vectors are in high abundance. In order to determine the clinical significance of these infections, blood and spleen samples, submitted by private equine veterinary practitioners over a 5-year period, from horses showing characteristic clinical signs of African horse sickness were tested for the presence of viral antigen using the antigen capture ELISA. The median sero-prevalence of AHSV antigen in horses recorded from these samples was 38% (IQR 33–88). The predominant AHSV antigen from these samples was serotype 7 (33%) followed by serotype 2 (26%) and serotypes 4 and 8 (16% each). African horse sickness virus serotypes 3 and 9, identified in this study, had not been previously reported in Zimbabwe.
African horse sickness caused by genome reassortment and reversion to virulence of live, attenuated vaccine viruses, South Africa, 2004-2014
(Centers for Disease Control and Prevention, 2016-12) Weyer, Camilla Theresa; Grewar, John Duncan; Burger, Phillipa; Rossouw, Esthea; Lourens, Carina W.; Joone, Christopher; le Granje, Misha; Coetzee, Peter; Venter, Estelle Hildegard; Martin, Darren P.; MacLachlan, N.J. (James); Guthrie, Alan John; alan.guthrie@up.ac.za
African horse sickness (AHS) is a hemorrhagic viral fever of horses. It is the only equine disease for which the World Organization for Animal Health has introduced specific guidelines for member countries seeking official recognition of disease-free status. Since 1997, South Africa has maintained an AHS controlled area; however, sporadic outbreaks of AHS have occurred in this area. We compared the whole genome sequences of 39 AHS viruses (AHSVs) from field AHS cases to determine the source of 3 such outbreaks. Our analysis confirmed that individual outbreaks were caused by virulent revertants of AHSV type 1 live, attenuated vaccine (LAV) and reassortants with genome segments derived from AHSV types 1, 3, and 4 from a LAV used in South Africa. These findings show that despite effective protection of vaccinated horses, polyvalent LAV may, paradoxically, place susceptible horses at risk for AHS.
Specifying and sustaining pigmentation patterns in domestic and wild cats
(American Association for the Advancement of Science, 2012-09) Kaelin, Christopher B.; Xu, Xiao; Hong, Lewis Z.; David, Victor A.; McGowan, Kelly A.; Schmidt-Küntzel, Anne; Roelke, Melody E.; Pino, Javier; Pontius, Joan; Cooper, Gregory M.; Manuel, Hermogenes; Swanson, William F.; Marker, Laurie; Harper, Cindy Kim; Van Dyk, Ann; Yue, Bisong; Mullikin, James C.; Warren, Wesley C.; Eizirik, Eduardo; Kos, Lidia; O’Brien, Stephen J.; Barsh, Gregory S.; Menotti-Raymond, Marilyn
Color markings among felid species display both a remarkable diversity and a common underlying periodicity. A similar range of patterns within domestic cats suggests a conserved mechanism whose appearance can be altered by selection. We identify the gene responsible for tabby pattern variation in domestic cats as Transmembrane aminopeptidase Q (Taqpep), which encodes a membrane-bound metalloprotease. Analyzing 31 other felid species we identify Taqpep as the cause of the rare king cheetah phenotype, in which spots coalesce into blotches and stripes. Histologic, genomic expression, and transgenic mouse studies indicate that paracrine expression of Endothelin3 (Edn3) coordinates localized color differences. We propose a two-stage model in which Taqpep helps to establish a periodic pre-pattern during skin development that is later implemented by differential expression of Edn3.
A PCR-based screening program to assess the prevalence of Taylorella equigenitalis in breeding stallions in South Africa
(Elsevier, 2012-11) Schulman, M.L. (Martin); May, Catherine Edith; Joone, C.J. (Carolynne); Monyai, Mpho S.; Gerstenberg, C.; Naidoo, R.; Pienaar, J.; Guthrie, Alan John
The first outbreak of Contagious Equine Metritis (CEM) due to Taylorella equigenitalis in South Africa was reported to the OIE in May 2011 subsequent to importation of a stallion, the index case. Two additional positive stallions were identified on an initial trace-back. The outbreak-response prompted determination of the national prevalence and distribution of CEM. A nation-wide PCR-based screening of all breeding stallions motivated by a previous outbreak report [1] was implemented via a mandatory CEM-negative clearance certificate prior to use for natural breeding or semen collection. Compliance from breeders was facilitated by developing a web-based system providing an easily-accessed, rapid and costeffective sampling, testing and reporting process on www.cemsa.co.za. A submission form, information, a breed-indexed list of stallions achieving CEM-clearance and a method for obtaining and submitting two sets of swabs (with an interval > 7d) from the external genitalia were accessible on the website. A duplex PCR was chosen as the assay method due to potential for submission of samples with minimal restrictions on transit time and temperature criteria and rapid, high throughput, cost-effi-ciency and reported sensitivity *1,2+. A clearance certificate was issued via the website after negative results from both sets of samples.
Missense mutation in the ligand-binding domain of the horse androgen receptor gene in a thoroughbred family with inherited 64,XY (SRY+) disorder of sex development
(Karger, 2016) Bolzon, Colin; Joone, C.J. (Carolynne); Schulman, M.L. (Martin); Harper, Cindy Kim; Villagómez, Daniel A.F.; King, W. Allan; Révay, Tamas
Disorders of sex development (DSD) have long been documented in domestic animal species including horses. However, there is only a single report of an androgen receptor mutation causative of such a DSD syndrome in a horse pedigree. Here, we present a new familial AR mutation in horses. A missense mutation (c.2042G>C) at AR exon 4 explains the segregation of the DSD in a Thoroughbred horse pedigree. The mutation, expected to affect the ligand-binding domain of the androgen receptor protein, led to complete androgen insensitivity of XY SRY+, testicular DSD individuals. Additionally, design of a PCR-RFLP technique provided an accurate molecular test for identification of horses carrying the mutation.
Single base-pair deletion in ASIP exon 3 associated with recessive black phenotype in impala (Aepyceros melampus)
(Wiley, 2016-08) Miller, Susan M.; Guthrie, Alan John; Harper, Cindy Kim
No abstract is available.

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