Insights into the Pathogenesis of Viral Haemorrhagic Fever Based on Virus Tropism and Tissue Lesions of Natural Rift Valley Fever.

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.

Refined experimental design may increase the value of murine models for estimation of bluetongue virus virulence.

Bluetongue is a serious non-contagious vector-borne viral disease in ruminants, causing poor animal welfare and economic consequences globally. Concern has been raised about the development of novel bluetongue virus (BTV) strains and their possibly altered virulence through the process of viral reassortment. Virulence is traditionally estimated in lethal dose 50 (LD) studies in murine models, but agreement with both and virulence in ruminants is questionable, and a refined experimental design is needed.

Potential link of single nucleotide polymorphisms to virulence of vaccine-associated field strains of lumpy skin disease virus in South Africa.

South Africa is endemic for lumpy skin disease and is therefore reliant on various live attenuated vaccines for the control and prevention of the disease. In recent years, widespread outbreaks of vaccine-like strains of lumpy skin disease virus (LSDV) were reported internationally, leading to an increase in the generation of full genome sequences from field isolates. In this study, the complete genomes of six LSDVs submitted during active outbreaks in the 1990s in South Africa were generated.

Complete Genome Sequences of Virus Strains Isolated from Bottle A of the South African Live Attenuated Bluetongue Virus Vaccine.

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.

Neutralizing antibodies against Rift Valley fever virus in wild antelope in far northern KwaZulu-Natal, South Africa, indicate recent virus circulation.

Rift Valley fever (RVF) is a zoonotic viral disease of domestic ruminants in Africa and the Arabian Peninsula caused by a mosquito-borne Phlebovirus. Outbreaks in livestock and humans occur after heavy rains favour breeding of vectors, and the virus is thought to survive dry seasons in the eggs of floodwater-breeding aedine mosquitoes. We recently found high seroconversion rates to RVF virus (RVFV) in cattle and goats, in the absence of outbreaks, in far northern KwaZulu-Natal (KZN), South Africa.

Phylogenetic Characterization of the Palyam Serogroup Orbiviruses.

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.

High seroconversion rate to Rift Valley fever virus in cattle and goats in far northern KwaZulu-Natal, South Africa, in the absence of reported outbreaks.

Background: Rift Valley fever (RVF) is a mosquito-borne zoonotic disease characterized in South Africa by large epidemics amongst ruminant livestock at very long, irregular intervals, mainly in the central interior. However, the presence and patterns of occurrence of the virus in the eastern parts of the country are poorly known. This study aimed to detect the presence of RVF virus (RVFV) in cattle and goats in far northern KwaZulu-Natal province and to estimate the prevalence of antibodies to the virus and the incidence rate of seroconversion.

Evaluating African horse sickness virus in horses and field-caught Culicoides biting midges on the East Rand, Gauteng Province, South Africa.

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 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.

Effect of using frozen-thawed bovine semen contaminated with lumpy skin disease virus on in vitro embryo production.

Lumpy skin disease (LSD) is an important transboundary animal disease of cattle with significant economic impact because of the implications for international trade in live animals and animal products. LSD is caused by a Capripoxvirus, LSD virus (LSDV), and results in extensive hide and udder damage, fever and pneumonia. LSDV can be shed in semen of infected bulls for prolonged periods and transmitted venereally to cows at high doses.

Reassortment of bluetongue virus vaccine serotypes in cattle.

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.

Phylogenetic analysis of canine distemper virus in South African wildlife.

Canine distemper virus (CDV) causes a severe contagious disease in a broad range of hosts. This is the first study to genetically characterise CDV strains from four different wildlife species in South Africa. The phylogenetic diversity of CDV is examined, using the haemagglutinin gene.

Effect of semen processing methods on lumpy skin disease virus status in cryopreserved bull semen.

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.

Genome Sequences of Three Vaccine Strains and Two Wild-Type Canine Distemper Virus Strains from a Recent Disease Outbreak in South Africa.

Canine distemper virus causes global multihost infectious disease. This report details complete genome sequences of three vaccine and two new wild-type strains. The wild-type strains belong to the South African lineage, and all three vaccine strains to the America 1 lineage.

Possible over-wintering of bluetongue virus in populations in the Onderstepoort area, Gauteng, South Africa.

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.

Advances in canine distemper virus pathogenesis research: a wildlife perspective.

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.

Rift Valley Fever Outbreak in Livestock, Mozambique, 2014.

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.

Complete Genome Sequences of Five Bluetongue Virus (BTV) Vaccine Strains from a Commercial Live Attenuated Vaccine, a BTV-4 Field Strain from South Africa, and a Reassortant Strain Isolated from Experimentally Vaccinated Cattle.

This is a report of the complete genome sequences of plaque-selected isolates of each of the five virus strains included in a South African commercial trivalent bluetongue virus (BTV) attenuated live virus vaccine, a BTV-4 field strain isolated from Rustenburg, South Africa, in 2011, and a bluetongue reassortant (bluetongue virus 4 strain 4/O. aries-tc/ZAF/11/OBP-115) isolated from experimentally vaccinated cattle. Full-genome sequencing and phylogenetic analyses show that the bluetongue virus 9 strain 9/B.

Sequence analysis and evaluation of the NS3/A gene region of bluetongue virus isolates from South Africa.

Phylogenetic networks and sequence analysis allow a more accurate understanding of the serotypes, genetic relationships and epidemiology of viruses. Based on gene sequences of the conserved segment 10 (NS3), bluetongue virus (BTV) 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 in the GenBank database.

Recent advances in knowledge of BTV‑host‑vector interaction.

Bluetongue virus (BTV) has since 1998 extended its distribution further North than where it has previously been encountered. Changes in the epidemiology of Bluetongue (BT), as well as novel features of recent outbreaks of BTV in Europe, have stimulated research on BTV‑vector‑host interaction. The outbreak of BTV‑8 in Northern Europe from 2006‑2008 is particular noteworthy in this regard, as the European strain of BTV‑8 demonstrated novel properties, including high virulence - especially for cattle - and the capability to cross the ruminant placenta.

Complete Genome Sequences of Four African Horse Sickness Virus Strains from a Commercial Tetravalent Live Attenuated Vaccine.

This is a report of the complete genome sequences of plaque-selected isolates of each of the four virus strains included in a South African commercial tetravalent African horse sickness attenuated live virus vaccine.

Complete Genome Sequences of the Three African Horse Sickness Virus Strains from a Commercial Trivalent Live Attenuated Vaccine.

This is a report of the complete genome sequences of plaque-selected isolates of each of the three virus strains included in a South African commercial trivalent African horse sickness attenuated live virus vaccine.

The effect of Rift Valley fever virus Clone 13 vaccine on semen quality in rams.

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.

Seroprevalence of Rift Valley fever and lumpy skin disease in African buffalo (Syncerus caffer) in the Kruger National Park and Hluhluwe-iMfolozi Park, South Africa.

Rift Valley fever and lumpy skin disease are transboundary viral diseases endemic in Africa and some parts of the Middle East, but with increasing potential for global emergence. Wild ruminants, such as the African buffalo (Syncerus caffer), are thought to play a role in the epidemiology of these diseases. This study sought to expand the understanding of the role of buffalo in the maintenance of Rift Valley fever virus (RVFV) and lumpy skin disease virus (LSDV) by determining seroprevalence to these viruses during an inter-epidemic period.

Culicoides species abundance and potential over-wintering of African horse sickness virus in the Onderstepoort area, Gauteng, South Africa.

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.