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Vaccines form the cornerstone of any control, eradication and preventative strategy and this is no different for lumpy skin disease. However, the usefulness of a vaccine is determined by a multiplicity of factors which include stability, efficiency, safety and ease of use, to name a few. Although the vaccination campaign in the Balkans against lumpy skin disease virus (LSDV) was successful and has been implemented with success in the past in other countries, data of vaccine failure have also been reported. It was therefore the purpose of this study to compare five homologous live attenuated LSDV vaccines (LSDV LAV) in a standardized setting. All five LSDV LAVs studied were able to protect against a challenge with virulent LSDV. Aside from small differences in serological responses, important differences were seen in side effects such as a local reaction and a Neethling response upon vaccination between the analyzed vaccines. These observations can have important implications in the applicability in the field for some of these LSDV LAVs.
Andy Haegeman; Ilse De Leeuw; Laurent Mostin; Willem Campe; Laetitia Aerts; Estelle Venter; Eeva Tuppurainen; Claude Saegerman; Kris De Clercq. Comparative Evaluation of Lumpy Skin Disease Virus-Based Live Attenuated Vaccines. Vaccines 2021, 9, 473 .
AMA StyleAndy Haegeman, Ilse De Leeuw, Laurent Mostin, Willem Campe, Laetitia Aerts, Estelle Venter, Eeva Tuppurainen, Claude Saegerman, Kris De Clercq. Comparative Evaluation of Lumpy Skin Disease Virus-Based Live Attenuated Vaccines. Vaccines. 2021; 9 (5):473.
Chicago/Turabian StyleAndy Haegeman; Ilse De Leeuw; Laurent Mostin; Willem Campe; Laetitia Aerts; Estelle Venter; Eeva Tuppurainen; Claude Saegerman; Kris De Clercq. 2021. "Comparative Evaluation of Lumpy Skin Disease Virus-Based Live Attenuated Vaccines." Vaccines 9, no. 5: 473.
Rift Valley fever phlebovirus (RVFV) infects humans and a wide range of ungulates and historically has caused devastating epidemics in Africa and the Arabian Peninsula. Lesions of naturally infected cases of Rift Valley fever (RVF) have only been described in detail in sheep with a few reports concerning cattle and humans. The most frequently observed lesion in both ruminants and humans is randomly distributed necrosis, particularly in the liver. Lesions supportive of vascular endothelial injury are also present and include mild hydropericardium, hydrothorax and ascites; marked pulmonary congestion and oedema; lymph node congestion and oedema; and haemorrhages in many tissues. Although a complete understanding of RVF pathogenesis is still lacking, antigen-presenting cells in the skin are likely the early targets of the virus. Following suppression of type I IFN production and necrosis of dermal cells, RVFV spreads systemically, resulting in infection and necrosis of other cells in a variety of organs. Failure of both the innate and adaptive immune responses to control infection is exacerbated by apoptosis of lymphocytes. An excessive pro-inflammatory cytokine and chemokine response leads to microcirculatory dysfunction. Additionally, impairment of the coagulation system results in widespread haemorrhages. Fatal outcomes result from multiorgan failure, oedema in many organs (including the lungs and brain), hypotension, and circulatory shock. Here, we summarize current understanding of RVF cellular tropism as informed by lesions caused by natural infections. We specifically examine how extant knowledge informs current understanding regarding pathogenesis of the haemorrhagic fever form of RVF, identifying opportunities for future research.
Lieza Odendaal; A Davis; Estelle Venter. Insights into the Pathogenesis of Viral Haemorrhagic Fever Based on Virus Tropism and Tissue Lesions of Natural Rift Valley Fever. Viruses 2021, 13, 709 .
AMA StyleLieza Odendaal, A Davis, Estelle Venter. Insights into the Pathogenesis of Viral Haemorrhagic Fever Based on Virus Tropism and Tissue Lesions of Natural Rift Valley Fever. Viruses. 2021; 13 (4):709.
Chicago/Turabian StyleLieza Odendaal; A Davis; Estelle Venter. 2021. "Insights into the Pathogenesis of Viral Haemorrhagic Fever Based on Virus Tropism and Tissue Lesions of Natural Rift Valley Fever." Viruses 13, no. 4: 709.
The Palyam serogroup orbiviruses are associated with abortion and teratogenesis in cattle and other ruminants. Of the 13 different serotypes that have been identified, the full genome sequence of only one, Kasba, has been published. We undertook to perform Next Generation Sequencing (NGS) and phylogenetic analysis on 12 Palyam serotypes plus field isolates of the African serotypes in our possession. The Palyam serogroup was found to be most closely related to the African horse sickness virus group and showed the most distant evolutionary relationship to the equine encephalosis viruses (EEV). Amino acid sequence analysis revealed that the gene encoding VP7 was the most conserved within serotypes and VP2 and VP5 showed the highest degree of variation. A high degree of sequence identity was found for isolates from the same geographical region. The phylogenetic analysis revealed two clades where the African serotypes were all very closely related in one clade and the other clade contained the Australian and Asian serotypes and one African serotype, Petevo. It was evident from the sequence data that the geographical origin of Palyam serogroup viruses played an important role in the development of the different serotypes.
Karen Ebersohn; Peter Coetzee; Louwrens P. Snyman; Robert Swanepoel; Estelle H. Venter. Phylogenetic Characterization of the Palyam Serogroup Orbiviruses. Viruses 2019, 11, 446 .
AMA StyleKaren Ebersohn, Peter Coetzee, Louwrens P. Snyman, Robert Swanepoel, Estelle H. Venter. Phylogenetic Characterization of the Palyam Serogroup Orbiviruses. Viruses. 2019; 11 (5):446.
Chicago/Turabian StyleKaren Ebersohn; Peter Coetzee; Louwrens P. Snyman; Robert Swanepoel; Estelle H. Venter. 2019. "Phylogenetic Characterization of the Palyam Serogroup Orbiviruses." Viruses 11, no. 5: 446.
Bluetongue is primarily a disease of sheep in South Africa, while cattle and goats are mostly subclinically infected. The viraemia of bluetongue virus in cattle lasts much longer than in sheep and the role of cattle in the epidemiology of bluetongue in South Africa is poorly understood. Bluetongue virus has a segmented double-stranded ribonucleic acid genome and reassortment of genomes is a common feature. The aim of the study was to investigate whether reassortment occurs between vaccine and field strains when simultaneously administered to cattle. Six cattle between the ages of 6 and 12 months were infected with five strains of modified live vaccine bluetongue virus and a virulent field isolate of bluetongue virus 4. Blood samples were subsequently collected daily from these animals from day 1 to day 39 post-inoculation. Viruses were directly isolated during viraemia from the buffy coat on Vero cells using the plaque forming unit method. Analysis of plaques indicated that no reassortants between virulent field and vaccine strains occurred and the virulent bluetongue virus 4 was identified as the predominant virus strain. However, a reassortant virus between two bluetongue virus vaccine strains was isolated from the buffy coat. Whole genome sequences from the vaccine viruses were compared to the suspected reassortant and it was found that segment 8 exchanged between the bluetongue virus 8 and bluetongue virus 9 vaccine strains. The use of the live-attenuated bluetongue virus multivalent vaccine in South Africa causes circulation of different vaccine serotypes in Culicoides spp. and susceptible hosts and cattle might provide the ideal host for reassortment to occur.
Carien Van Den Bergh; Peter Coetzee; Estelle H. Venter. Reassortment of bluetongue virus vaccine serotypes in cattle. Journal of the South African Veterinary Association 2018, 89, 7 -e7.
AMA StyleCarien Van Den Bergh, Peter Coetzee, Estelle H. Venter. Reassortment of bluetongue virus vaccine serotypes in cattle. Journal of the South African Veterinary Association. 2018; 89 ():7-e7.
Chicago/Turabian StyleCarien Van Den Bergh; Peter Coetzee; Estelle H. Venter. 2018. "Reassortment of bluetongue virus vaccine serotypes in cattle." Journal of the South African Veterinary Association 89, no. : 7-e7.
Lumpy skin disease is an economically important disease of cattle, caused by the lumpy skin disease virus (LSDV; Capripoxvirus). It has a variable clinical appearance but, in severely affected animals, is associated with extensive skin damage, pneumonia and death. The LSDV can be found in the semen of infected bulls for prolonged periods of time, from where it can be transmitted by mating or artificial insemination and cause clinical disease in heifers and cows. In this study, an ejaculate was collected from a LSDV seronegative bull and confirmed free from LSDV DNA by PCR. The ejaculate was split into a control sample (C), a sample spiked with a 4 log TCID50 dose of an LSDV isolate (HD) and a 103 dilution of the virus suspension (ND) and frozen routinely. Two straws from each of the different semen treatment groups (HD, ND and C) were subsequently thawed and subjected to swim-up, single layer centrifugation, Percoll® density gradient and a Percoll® density gradient with added trypsin. For one set of straws, semen quality variables were recorded, and viral DNA status determined using PCR; the other set was used for positive staining electron microscopy. Samples determined to be positive for LSDV DNA by PCR were then subjected to virus isolation (VI). Complete elimination of LSDV from semen did not occur with use of any of the processing methods. Trypsin did reduce the viral load, and eliminated LSDV from the ND sample, but severely negatively influenced semen quality. The LSDV virions, as assessed by electron microscopy, were associated with the sperm plasma membrane. Further investigation is needed to establish the efficacy of immuno-extenders for rendering semen free from LSDV.
C. Henry Annandale; Mario Smuts; Karen Ebersohn; Lizette Du Plessis; Estelle H. Venter; Tom A.E. Stout. Effect of semen processing methods on lumpy skin disease virus status in cryopreserved bull semen. Animal Reproduction Science 2018, 195, 24 -29.
AMA StyleC. Henry Annandale, Mario Smuts, Karen Ebersohn, Lizette Du Plessis, Estelle H. Venter, Tom A.E. Stout. Effect of semen processing methods on lumpy skin disease virus status in cryopreserved bull semen. Animal Reproduction Science. 2018; 195 ():24-29.
Chicago/Turabian StyleC. Henry Annandale; Mario Smuts; Karen Ebersohn; Lizette Du Plessis; Estelle H. Venter; Tom A.E. Stout. 2018. "Effect of semen processing methods on lumpy skin disease virus status in cryopreserved bull semen." Animal Reproduction Science 195, no. : 24-29.
Angelika K. Loots; Elaine Cardoso-Vermaak; Estelle H. Venter; Emily Mitchell; Antoinette Kotzé; Desiré L. Dalton. The role of toll-like receptor polymorphisms in susceptibility to canine distemper virus. Mammalian Biology 2018, 88, 94 -99.
AMA StyleAngelika K. Loots, Elaine Cardoso-Vermaak, Estelle H. Venter, Emily Mitchell, Antoinette Kotzé, Desiré L. Dalton. The role of toll-like receptor polymorphisms in susceptibility to canine distemper virus. Mammalian Biology. 2018; 88 ():94-99.
Chicago/Turabian StyleAngelika K. Loots; Elaine Cardoso-Vermaak; Estelle H. Venter; Emily Mitchell; Antoinette Kotzé; Desiré L. Dalton. 2018. "The role of toll-like receptor polymorphisms in susceptibility to canine distemper virus." Mammalian Biology 88, no. : 94-99.
Canine distemper virus (CDV) has emerged as a significant disease of wildlife, which is highly contagious and readily transmitted between susceptible hosts. Initially described as an infectious disease of domestic dogs, it is now recognized as a global multi-host pathogen, infecting and causing mass mortalities in a wide range of carnivore species. The last decade has seen the effect of numerous CDV outbreaks in various wildlife populations. Prevention of CDV requires a clear understanding of the potential hosts in danger of infection as well as the dynamic pathways CDV uses to gain entry to its host cells and its ability to initiate viral shedding and disease transmission. We review recent research conducted on CDV infections in wildlife, including the latest findings on the causes of host specificity and cellular receptors involved in distemper pathogenesis.
Angelika K Loots; Emily Mitchell; Desire Lee Dalton; Antoinette Kotzé; Estelle H Venter. Advances in canine distemper virus pathogenesis research: a wildlife perspective. Journal of General Virology 2017, 98, 311 -321.
AMA StyleAngelika K Loots, Emily Mitchell, Desire Lee Dalton, Antoinette Kotzé, Estelle H Venter. Advances in canine distemper virus pathogenesis research: a wildlife perspective. Journal of General Virology. 2017; 98 (3):311-321.
Chicago/Turabian StyleAngelika K Loots; Emily Mitchell; Desire Lee Dalton; Antoinette Kotzé; Estelle H Venter. 2017. "Advances in canine distemper virus pathogenesis research: a wildlife perspective." Journal of General Virology 98, no. 3: 311-321.
In early 2014, abortions and death of ruminants were reported on farms in Maputo and Gaza Provinces, Mozambique. Serologic analysis and quantitative and conventional reverse transcription PCR confirmed the presence of Rift Valley fever virus. The viruses belonged to lineage C, which is prevalent among Rift Valley fever viruses in southern Africa.
José M. Fafetine; Peter Coetzee; Benjamin Mubemba; Ofélia Nhambirre; Luis Neves; J.A.W. Coetzer; Estelle H. Venter. Rift Valley Fever Outbreak in Livestock, Mozambique, 2014. Emerging Infectious Diseases 2016, 22, 1 .
AMA StyleJosé M. Fafetine, Peter Coetzee, Benjamin Mubemba, Ofélia Nhambirre, Luis Neves, J.A.W. Coetzer, Estelle H. Venter. Rift Valley Fever Outbreak in Livestock, Mozambique, 2014. Emerging Infectious Diseases. 2016; 22 (12):1.
Chicago/Turabian StyleJosé M. Fafetine; Peter Coetzee; Benjamin Mubemba; Ofélia Nhambirre; Luis Neves; J.A.W. Coetzer; Estelle H. Venter. 2016. "Rift Valley Fever Outbreak in Livestock, Mozambique, 2014." Emerging Infectious Diseases 22, no. 12: 1.
Several studies have demonstrated the ability of certain viruses to overwinter in arthropod vectors. The over-wintering mechanism of bluetongue virus (BTV) is unknown. One hypothesis is over-wintering within adult Culicoides midges (Diptera; Ceratopogonidae) that survive mild winters where temperatures seldom drop below 10 °C. The reduced activity of midges and the absence of outbreaks during winter may create the impression that the virus has disappeared from an area. Light traps were used in close association with horses to collect Culicoides midges from July 2010 to September 2011 in the Onderstepoort area, in Gauteng Province, South Africa. More than 500 000 Culicoides midges were collected from 88 collections and sorted to species level, revealing 26 different Culicoides species. Culicoides midges were present throughout the 15 month study. Nine Culicoides species potentially capable of transmitting BTV were present during the winter months. Midges were screened for the presence of BTV ribonucleic acid (RNA) with the aid of a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) assay. In total 91.2% of midge pools tested positive for BTV RNA. PCR results were compared with previous virus isolation results (VI) that demonstrated the presence of viruses in summer and autumn months. The results indicate that BTV-infected Culicoides vectors are present throughout the year in the study area. Viral RNA-positive midges were also found throughout the year with VI positive midge pools only in summer and early autumn. Midges that survive mild winter temperatures could therefore harbour BTV but with a decreased vector capacity. When the population size, biting rate and viral replication decrease, it could stop BTV transmission. Over-wintering of BTV in the Onderstepoort region could therefore result in re-emergence because of increased vector activity rather than reintroduction from outside the region.
Jumari Steyn; Gert J. Venter; Karien Labuschagne; Daphney Majatladi; Solomon N.B. Boikanyo; Carina Lourens; Karen Ebersohn; Estelle H. Venter. Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa. Journal of the South African Veterinary Association 2016, 87, 5 pages .
AMA StyleJumari Steyn, Gert J. Venter, Karien Labuschagne, Daphney Majatladi, Solomon N.B. Boikanyo, Carina Lourens, Karen Ebersohn, Estelle H. Venter. Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa. Journal of the South African Veterinary Association. 2016; 87 (1):5 pages.
Chicago/Turabian StyleJumari Steyn; Gert J. Venter; Karien Labuschagne; Daphney Majatladi; Solomon N.B. Boikanyo; Carina Lourens; Karen Ebersohn; Estelle H. Venter. 2016. "Possible over-wintering of bluetongue virus in Culicoides populations in the Onderstepoort area, Gauteng, South Africa." Journal of the South African Veterinary Association 87, no. 1: 5 pages.
Phylogenetic networks and sequence analyses allow for a more accurate understanding of the serotype, genetic relationships and the epidemiology of viruses. Based on gene sequences of the conserved segment 10 (NS3), bluetongue virus can be divided into five topotypes. In this molecular epidemiology study, segment 10 sequence data of 11 isolates obtained from the Virology Section of the Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, were analyzed and compared to sequence data of worldwide BTV strains available on GenBank. The consensus nucleotide sequences of NS3/A showed intermediate levels of nucleotide variation with a nucleotide identity ranging from 79.72% to 100%. All 11 strains demonstrated conserved amino acid characteristics. Phylogenetic networks were used to identify BTV topotypes. The phylogeny obtained from the nucleotide sequence data of the NS3/A-encoding gene presented three major and two minor topotypes. The clustering of strains from different geographical areas into the same group indicated spatial spread of the segment 10 genes, either through gene reassortment or through the introduction of new strains from other geographical areas via trade. The effect of reassortment and genetic drift on BTV and the importance of correct serotyping to identify viral strains are highlighted.The National Research Foundation and the Meat Industry Trust.http://link.springer.com/journal/7052017-04-30hb2016Veterinary Tropical Disease
Jumari Steyn; Estelle Hildegard Venter. Sequence analysis and evaluation of the NS3/A gene region of bluetongue virus isolates from South Africa. Archives of Virology 2016, 161, 947 -957.
AMA StyleJumari Steyn, Estelle Hildegard Venter. Sequence analysis and evaluation of the NS3/A gene region of bluetongue virus isolates from South Africa. Archives of Virology. 2016; 161 (4):947-957.
Chicago/Turabian StyleJumari Steyn; Estelle Hildegard Venter. 2016. "Sequence analysis and evaluation of the NS3/A gene region of bluetongue virus isolates from South Africa." Archives of Virology 161, no. 4: 947-957.
Ostrich (Struthio camelus) chicks less than 3 mo age are observed to experience a high mortality rate that is often associated with enteritis. This study was undertaken to investigate the infectious bacteria implicated in ostrich chick enteritis. Postmortems were performed on 122 ostrich chicks aged from 1 d to 3 mo and intestinal samples were subjected to bacterial culture. Bacterial isolates were typed by PCR and serotyping. Escherichia coli (E. coli; 49%) was the most frequently isolated from the samples followed by Clostridium perfringens (C. perfringens; 20%), Enterococcus spp. (16%), and Salmonella spp. (7%). Of the E. coli, 39% were categorized as enteropathogenic E. coli, 4% enterotoxigenic E. coli, and no enterohaemorrhagic E. coli were found. The majority (93%) of C. perfringens was Type A and only 7% was Type E. C. perfringens Types B through D were not present. The netB gene that encodes NetB toxin was identified from 16% of the C. perfringens isolated. All the C. perfringens Type E harbored the netB gene and just 10% of the C. perfringens Type A had this gene. Three Salmonella serotypes were identified: Salmonella Muenchen (S. Muenchen; 80%), S. Hayindongo (13%), and S. Othmarschen (7%). The indication is that the cause of enteritis in ostrich chicks is bacterial-involving: enteropathogenic E. coli and enterotoxigenic E. coli; C. perfringens Types A and E (with the possible influence of netB gene); and S. Muenchen, S. Hayindongo, and S. Othmarschen.
L. Keokilwe; A. Olivier; W. P. Burger; H. Joubert; Estelle Venter; Darshana Morar-Leather. Bacterial enteritis in ostrich (Struthio Camelus) chicks in the Western Cape Province, South Africa. Poultry Science 2015, 94, 1177 -1183.
AMA StyleL. Keokilwe, A. Olivier, W. P. Burger, H. Joubert, Estelle Venter, Darshana Morar-Leather. Bacterial enteritis in ostrich (Struthio Camelus) chicks in the Western Cape Province, South Africa. Poultry Science. 2015; 94 (6):1177-1183.
Chicago/Turabian StyleL. Keokilwe; A. Olivier; W. P. Burger; H. Joubert; Estelle Venter; Darshana Morar-Leather. 2015. "Bacterial enteritis in ostrich (Struthio Camelus) chicks in the Western Cape Province, South Africa." Poultry Science 94, no. 6: 1177-1183.
Rift Valley fever (RVF) is an arthropod-borne viral disease of importance in livestock and humans. Epidemics occur periodically in domestic ruminants. People in contact with infected livestock may develop disease that varies from mild flu-like symptoms to fatal viraemia. Livestock vaccination may assist in disease control. Rift Valley fever virus (RVFV) Clone 13 is a relatively new vaccine against RVF, derived from an avirulent natural mutant strain of RVFV, and has been shown to confer protective immunity against experimental infection with RVFV. The hypothesis tested in the current trial was that rams vaccinated with RVFV Clone 13 vaccine would not experience a reduction in semen quality (measured by evaluating the percentage progressively motile and percentage morphologically normal spermatozoa in successive ejaculates) relative to unvaccinated control animals. Ram lambs were screened for antibodies to RVFV using a serum neutralisation test. Animals without detectable antibodies (n = 23) were randomly allocated to either a test group (n = 12) or a control group (n = 11). Animals in the test group were vaccinated with RVFV Clone 13 vaccine. Daily rectal temperature measurements and weekly semen and blood samples were taken from all animals. Seven animals were eliminated from the statistical analysis because of potential confounding factors. Logistic regression analysis was performed on data gathered from the remaining animals to determine whether an association existed between animal group, rectal temperature and semen quality parameters. No correlation existed between the treatment group and values obtained for the semen quality parameters measured. There was no statistically significant post-vaccination decline in the percentage of live morphologically normal spermatozoa, or the percentage of progressively motile spermatozoa, either when assessed amongst all animals or when assessed within individual groups. A repeat study with a larger sample size and a more comprehensive pre-screening process may be indicated to avoid the inclusion of unsuitable animals.
Geoff Brown; Estelle H. Venter; Paul Morley; Henry Annandale. The effect of Rift Valley fever virus Clone 13 vaccine on semen quality in rams. Onderstepoort Journal of Veterinary Research 2015, 82, 8 .
AMA StyleGeoff Brown, Estelle H. Venter, Paul Morley, Henry Annandale. The effect of Rift Valley fever virus Clone 13 vaccine on semen quality in rams. Onderstepoort Journal of Veterinary Research. 2015; 82 (1):8.
Chicago/Turabian StyleGeoff Brown; Estelle H. Venter; Paul Morley; Henry Annandale. 2015. "The effect of Rift Valley fever virus Clone 13 vaccine on semen quality in rams." Onderstepoort Journal of Veterinary Research 82, no. 1: 8.
Lumpy skin disease (LSD) is of substantial economic importance for the cattle industry in Africa and the Near and Middle East. Several insect species are thought to transmit the disease mechanically. Recent transmission studies have demonstrated the first evidence for a role of hard (ixodid) ticks as vectors of lumpy skin disease virus (LSDV). The aim of this study was to attempt in vitro growth of the virus in Rhipicephalus spp. tick cell lines and investigate in vivo the presence of the virus in ticks collected from cattle during LSD outbreaks in Egypt and South Africa. No evidence was obtained for replication of LSDV in tick cell lines although the virus was remarkably stable, remaining viable for 35 days at 28 °C in tick cell cultures, in growth medium used for tick cells and in phosphate buffered saline. Viral DNA was detected in two-thirds of the 56 field ticks, making this the first report of the presence of potentially virulent LSDV in ticks collected from naturally infected animals.
E.S.M. Tuppurainen; Estelle Venter; J.A.W. Coetzer; L. Bell-Sakyi. Lumpy skin disease: Attempted propagation in tick cell lines and presence of viral DNA in field ticks collected from naturally-infected cattle. Ticks and Tick-borne Diseases 2014, 6, 134 -140.
AMA StyleE.S.M. Tuppurainen, Estelle Venter, J.A.W. Coetzer, L. Bell-Sakyi. Lumpy skin disease: Attempted propagation in tick cell lines and presence of viral DNA in field ticks collected from naturally-infected cattle. Ticks and Tick-borne Diseases. 2014; 6 (2):134-140.
Chicago/Turabian StyleE.S.M. Tuppurainen; Estelle Venter; J.A.W. Coetzer; L. Bell-Sakyi. 2014. "Lumpy skin disease: Attempted propagation in tick cell lines and presence of viral DNA in field ticks collected from naturally-infected cattle." Ticks and Tick-borne Diseases 6, no. 2: 134-140.
Bluetongue virus (BTV), a segmented dsRNA virus, is the causative agent of bluetongue (BT), an economically important viral haemorrhagic disease of ruminants. Bluetongue virus can exchange its genome segments in mammalian or insect cells that have been co-infected with more than one strain of the virus. This process, may potentially give rise to the generation of novel reassortant strains that may differ from parental strains in regards to their phenotypic characteristics. To investigate the potential effects of reassortment on the virus’ phenotype, parental as well as reassortant strains of BTV serotype 1, 6, 8, that were derived from attenuated, and wild type strains by reverse genetics, were studied in vitro for their virus replication kinetics and cytopathogenicity in mammalian (Vero) cell cultures. The results indicate that genetic reassortment can affect viral replication kinetics, the cytopathogenicity and extent/mechanism of cell death in infected cell cultures. In particular, some reassortants of non-virulent vaccine (BTV-1 and BTV-6) and virulent field origin (BTV-8) demonstrate more pronounced cytopathic effects compared to their parental strains. Some reassortant strains in addition replicated to high titres in vitro despite being composed of genome segments from slow and fast replicating parental strains. The latter result may have implications for the level of viraemia in the mammalian host and subsequent uptake and transmission of reassortant strains (and their genome segments) by Culicoides vectors. Increased rates of CPE induction could further suggest a higher virulence for reassortant strains in vivo. Overall, these findings raise questions in regards to the use of modified-live virus (MLV) vaccines and risk of reassortment in the field. To further address these questions, additional experimental infection studies using insects and/or animal models should be conducted, to determine whether these results have significant implications in vivo.Norwegian State Educational Loan Fund (Lånekassen), Tine Dairy Cooperative (Norway), Animalia Meat and Poultry Research Centre (Norway), the IRT (Genomics) working group of the University of Pretoria, and the Ministry of Economic Affairs (CVI-project 1691022500),http://www.elsevier.com/locate/vetmichb2014ab201
Peter Coetzee; Moritz Van Vuuren; Maria Stokstad; Mette Myrmel; René G.P. Van Gennip; Piet A. Van Rijn; Estelle Hildegard Venter. Viral replication kinetics and in vitro cytopathogenicity of parental and reassortant strains of bluetongue virus serotype 1, 6 and 8. Veterinary Microbiology 2014, 171, 53 -65.
AMA StylePeter Coetzee, Moritz Van Vuuren, Maria Stokstad, Mette Myrmel, René G.P. Van Gennip, Piet A. Van Rijn, Estelle Hildegard Venter. Viral replication kinetics and in vitro cytopathogenicity of parental and reassortant strains of bluetongue virus serotype 1, 6 and 8. Veterinary Microbiology. 2014; 171 (1-2):53-65.
Chicago/Turabian StylePeter Coetzee; Moritz Van Vuuren; Maria Stokstad; Mette Myrmel; René G.P. Van Gennip; Piet A. Van Rijn; Estelle Hildegard Venter. 2014. "Viral replication kinetics and in vitro cytopathogenicity of parental and reassortant strains of bluetongue virus serotype 1, 6 and 8." Veterinary Microbiology 171, no. 1-2: 53-65.
Estelle Venter. Lumpy Skin Disease Virus. Manual of Security Sensitive Microbes and Toxins 2014, 665 -678.
AMA StyleEstelle Venter. Lumpy Skin Disease Virus. Manual of Security Sensitive Microbes and Toxins. 2014; ():665-678.
Chicago/Turabian StyleEstelle Venter. 2014. "Lumpy Skin Disease Virus." Manual of Security Sensitive Microbes and Toxins , no. : 665-678.
African horse sickness virus (AHSV) is an arbovirus capable of successfully replicating in both its mammalian host and insect vector. Where mammalian cells show a severe cytopathic effect (CPE) following AHSV infection, insect cells display no CPE. These differences in cell death could be linked to the method of viral release, i.e. lytic or non-lytic, that predominates in a specific cell type. Active release of AHSV, or any related orbivirus, has, however, not yet been documented from insect cells. We applied an integrated microscopy approach to compare the nanomechanical and morphological response of mammalian and insect cells to AHSV infection. Atomic force microscopy revealed plasma membrane destabilization, integrity loss and structural deformation of the entire surface of infected mammalian cells. Infected insect cells, in contrast, showed no morphological differences from mock-infected cells other than an increased incidence of circular cavities present on the cell surface. Transmission electron microscopy imaging identified a novel large vesicle-like compartment within infected insect cells, not present in mammalian cells, containing viral proteins and virus particles. Extracellular clusters of aggregated virus particles were visualized adjacent to infected insect cells with intact plasma membranes. We propose that foreign material is accumulated within these vesicles and that their subsequent fusion with the cell membrane releases entrapped viruses, thereby facilitating a non-lytic virus release mechanism different from the budding previously observed in mammalian cells. This insect cell-specific defence mechanism contributes to the lack of cell damage observed in AHSV-infected insect cells.
Estelle Venter; C. F. Van Der Merwe; A. V. Buys; H. Huismans; V. Van Staden. Comparative ultrastructural characterization of African horse sickness virus-infected mammalian and insect cells reveals a novel potential virus release mechanism from insect cells. Journal of General Virology 2014, 95, 642 -651.
AMA StyleEstelle Venter, C. F. Van Der Merwe, A. V. Buys, H. Huismans, V. Van Staden. Comparative ultrastructural characterization of African horse sickness virus-infected mammalian and insect cells reveals a novel potential virus release mechanism from insect cells. Journal of General Virology. 2014; 95 (3):642-651.
Chicago/Turabian StyleEstelle Venter; C. F. Van Der Merwe; A. V. Buys; H. Huismans; V. Van Staden. 2014. "Comparative ultrastructural characterization of African horse sickness virus-infected mammalian and insect cells reveals a novel potential virus release mechanism from insect cells." Journal of General Virology 95, no. 3: 642-651.
Lumpy skin disease (LSD) is caused by lumpy skin disease virus (LSDV), a member of the genus Capripoxvirus. Transmission of the virus has been associated with haematophagous insects such as Stomoxys calcitrans as well as Aedes and Culex species of mosquitoes. Recent studies have reported the transmission of the virus by Amblyomma hebraeum, Rhipicephalus appendiculatus, and Rhipicephalus decoloratus ticks and the presence of LSDV in saliva of A. hebraeum and R. appendiculatus ticks. The aim of this study was to determine which tick organs become infected by LSDV following intrastadial infection and transstadial persistence of the virus in A. hebraeum and R. appendiculatus ticks. Nymphal and adult ticks were orally infected by feeding them on LSDV-infected cattle. Partially fed adult ticks were processed for testing while nymphs were fed to repletion and allowed to moult to adults before being processed for testing. The infection in tick organs was determined by testing for the presence of the viral antigen using monoclonal antibodies with immunohistochemical staining. The viral antigen was detected in salivary glands, haemocytes, synganglia, ovaries, testes, fat bodies, and midgut. Since the virus was shown to be able to cross the midgut wall and infect various tick organs, this may indicate potential for biological development and transmission of LSDV in ticks. This study strengthens the previously reported evidence of the occurrence of LSDV in tick saliva.http://www.elsevier.com/locate/ttbdishb2014ab201
Jimmy Clement Lubinga; Sarah Clift; Eeva S.M. Tuppurainen; Wilhelm Heinrich Stoltsz; Shawn Babiuk; Jacobus A.W. Coetzer; Estelle Venter. Demonstration of lumpy skin disease virus infection in Amblyomma hebraeum and Rhipicephalus appendiculatus ticks using immunohistochemistry. Ticks and Tick-borne Diseases 2014, 5, 113 -120.
AMA StyleJimmy Clement Lubinga, Sarah Clift, Eeva S.M. Tuppurainen, Wilhelm Heinrich Stoltsz, Shawn Babiuk, Jacobus A.W. Coetzer, Estelle Venter. Demonstration of lumpy skin disease virus infection in Amblyomma hebraeum and Rhipicephalus appendiculatus ticks using immunohistochemistry. Ticks and Tick-borne Diseases. 2014; 5 (2):113-120.
Chicago/Turabian StyleJimmy Clement Lubinga; Sarah Clift; Eeva S.M. Tuppurainen; Wilhelm Heinrich Stoltsz; Shawn Babiuk; Jacobus A.W. Coetzer; Estelle Venter. 2014. "Demonstration of lumpy skin disease virus infection in Amblyomma hebraeum and Rhipicephalus appendiculatus ticks using immunohistochemistry." Ticks and Tick-borne Diseases 5, no. 2: 113-120.
Bluetongue (BT) is a non-contagious disease of sheep and other domestic and wild ruminants caused by the bluetongue virus (BTV). Currently 26 serotypes of the virus have been identified. In South Africa, 22 serotypes have been identified and BT is controlled mainly by annual vaccinations using a freeze-dried live attenuated polyvalent BTV vaccine. The vaccine is constituted of 15 BTV serotypes divided into three separate bottles and the aim is to develop a vaccine using fewer serotypes without compromising the immunity against the disease. This study is based on previously reported cross-neutralisation of specific BTV serotypes in in vitro studies. Bluetongue virus serotype 4 was selected for this trial and was tested for cross-protection against serotype 4 (control), 1 (unrelated serotype), 9, 10 and 11 in sheep using the serum neutralisation test. The purpose of the study was to determine possible cross-protection of different serotypes in sheep. Of those vaccinated with BTV-4 and challenged with BTV-1, which is not directly related to BTV-4, 20% were completely protected and 80% showed clinical signs, but the reaction was not as severe as amongst the unvaccinated animals. In the group challenged with BTV-10, some showed good protection and some became very sick. Those challenged with BTV-9 and BTV-11 had good protection. The results showed that BTV-4 does not only elicit a specific immune response but can also protect against other serotypes.
Gcwalisile B. Zulu; Estelle H. Venter. Evaluation of cross-protection of bluetongue virus serotype 4 with other serotypes in sheep. Journal of the South African Veterinary Association 2014, 85, 2 .
AMA StyleGcwalisile B. Zulu, Estelle H. Venter. Evaluation of cross-protection of bluetongue virus serotype 4 with other serotypes in sheep. Journal of the South African Veterinary Association. 2014; 85 (1):2.
Chicago/Turabian StyleGcwalisile B. Zulu; Estelle H. Venter. 2014. "Evaluation of cross-protection of bluetongue virus serotype 4 with other serotypes in sheep." Journal of the South African Veterinary Association 85, no. 1: 2.
Fowl adenovirus (FAdV) is a member of the genus Aviadenovirus and causes a number of economically important poultry diseases. One of these diseases, inclusion body hepatitis (IBH), has a worldwide distribution and is characterised by acute mortality (5% - 20%) in production chickens. The disease was first described in the United States of America in 1963 and has also been reported in Canada, the United Kingdom, Australia, France and Ireland, but until now, not in South Africa. Adenoviruses isolated from the first outbreak of IBH in South Africa were able to reproduce the disease in chicken embryo livers. The aim of the present study was to characterise the viruses and determine the pathogenicity of the FAdV strains responsible for the first reported case of IBH in South Africa. Polymerase chain reaction (PCR) amplification of the L1 loop region of the fowl adenovirus hexon gene using degenerate primer pair hexon A/B was used to identify the viruses that were isolated. Restriction fragment length polymorphism (RFLP) of the amplification products was used for the differentiation of 14 isolates of fowl adenovirus. Sequencing of the PCR products followed by amino acid comparison and phylogenetic analysis using the L1 loop region of the hexon protein was done to determine the identity of the isolates. Amino acid sequences of the hexon genes of all the South African isolates were compared with those of reference strains representing FAdV species. Amino acid comparison of 12 South Africa field isolates to FAdV reference strains revealed a high sequence identity (> 93.33%) with reference strains T8-A and 764. Two of the isolates had high sequence identity (93.40%) with reference strains P7-A, C2B and SR48. Phylogenetic analysis of the L1 loop region of the hexon protein of all 14 South African isolates was consistent with their RFLP clusters. The mortality rates of embryos challenged with 106 egg infective doses (EID50) FAdV 2 were 80% - 87% and mortality rates for embryos challenged with 105.95 (EID50) FAdV 8b were 65% - 80%.
Hilda W. Joubert; Henry Aitchison; Louis H. Maartens; Estelle H. Venter. Molecular differentiation and pathogenicity of Aviadenoviruses isolated during an outbreak of inclusion body hepatitis in South Africa. Journal of the South African Veterinary Association 2014, 85, 8 .
AMA StyleHilda W. Joubert, Henry Aitchison, Louis H. Maartens, Estelle H. Venter. Molecular differentiation and pathogenicity of Aviadenoviruses isolated during an outbreak of inclusion body hepatitis in South Africa. Journal of the South African Veterinary Association. 2014; 85 (1):8.
Chicago/Turabian StyleHilda W. Joubert; Henry Aitchison; Louis H. Maartens; Estelle H. Venter. 2014. "Molecular differentiation and pathogenicity of Aviadenoviruses isolated during an outbreak of inclusion body hepatitis in South Africa." Journal of the South African Veterinary Association 85, no. 1: 8.
In South Africa, outbreaks of African horse sickness (AHS) occur in summer; no cases are reported in winter, from July to September. The AHS virus (AHSV) is transmitted almost exclusively by Culicoides midges (Diptera: Ceratopogonidae), of which Culicoides imicola is considered to be the most important vector. The over-wintering mechanism of AHSV is unknown. In this study, more than 500 000 Culicoides midges belonging to at least 26 species were collected in 88 light traps at weekly intervals between July 2010 and September 2011 near horses in the Onderstepoort area of South Africa. The dominant species was C. imicola. Despite relatively low temperatures and frost, at least 17 species, including C. imicola, were collected throughout winter (June-August). Although the mean number of midges per night fell from > 50 000 (March) to < 100 (July and August), no midge-free periods were found. This study, using virus isolation on cell cultures and a reverse transcriptase polymerase chain reaction (RT-PCR) assay, confirmed low infection prevalence in field midges and that the detection of virus correlated to high numbers. Although no virus was detected during this winter period, continuous adult activity indicated that transmission can potentially occur. The absence of AHSV in the midges during winter can be ascribed to the relatively low numbers collected coupled to low infection prevalence, low virus replication rates and low virus titres in the potentially infected midges. Cases of AHS in susceptible animals are likely to start as soon as Culicoides populations reach a critical level.
Gert J. Venter; Karien Labuschagne; Daphney Majatladi; Solomon N.B. Boikanyo; Carina Lourens; Karen Ebersohn; Estelle H. Venter. Culicoides species abundance and potential over-wintering of African horse sickness virus in the Onderstepoort area, Gauteng, South Africa. Journal of the South African Veterinary Association 2014, 85, 6 .
AMA StyleGert J. Venter, Karien Labuschagne, Daphney Majatladi, Solomon N.B. Boikanyo, Carina Lourens, Karen Ebersohn, Estelle H. Venter. Culicoides species abundance and potential over-wintering of African horse sickness virus in the Onderstepoort area, Gauteng, South Africa. Journal of the South African Veterinary Association. 2014; 85 (1):6.
Chicago/Turabian StyleGert J. Venter; Karien Labuschagne; Daphney Majatladi; Solomon N.B. Boikanyo; Carina Lourens; Karen Ebersohn; Estelle H. Venter. 2014. "Culicoides species abundance and potential over-wintering of African horse sickness virus in the Onderstepoort area, Gauteng, South Africa." Journal of the South African Veterinary Association 85, no. 1: 6.