Moritz Van Vuuren

A Serologic Survey of Wild Felids from Central West Saudi Arabia

Forty-five wildcats (Felis silvestris), 17 sand cats (Felis margarita), and 17 feral domestic cats were captured in central west Saudi Arabia, between May 1998 and April 2000, with the aim to assess their exposure to feline immunodeficiency virus/puma lentivirus (FIV/PLV), feline leukaemia virus (FeLV), feline herpesvirus (FHV-1), feline calicivirus (FCV), feline coronavirus (FCoV), and feline panleukopenia virus (FPLV). Serologic prevalence in wildcats, sand cats, and feral domestic cats were respectively: 6%, 0%, 8% for FIV/PLV; 3%, 8%, 0% for FeLV; 5%, 0%, 15% for FHV-1; 25%, 0%, 39% for FCV; 10%, 0%, 0% for FCoV; and 5%, 0%, 8% for FPLV. We recorded the first case of FeLV antigenemia in a wild sand cat. Positive results to FIV/PLV in wildcats and feral cats confirmed the occurrence of a feline lentivirus in the sampled population.

Bluetongue: a historical and epidemiological perspective with the emphasis on South Africa

Bluetongue (BT) is a non-contagious, infectious, arthropod transmitted viral disease of domestic and wild ruminants that is caused by the bluetongue virus (BTV), the prototype member of the Orbivirus genus in the family Reoviridae. Bluetongue was first described in South Africa, where it has probably been endemic in wild ruminants since antiquity. Since its discovery BT has had a major impact on sheep breeders in the country and has therefore been a key focus of research at the Onderstepoort Veterinary Research Institute in Pretoria, South Africa. Several key discoveries were made at this Institute, including the demonstration that the aetiological agent of BT was a dsRNA virus that is transmitted by Culicoides midges and that multiple BTV serotypes circulate in nature. It is currently recognized that BT is endemic throughout most of South Africa and 22 of the 26 known serotypes have been detected in the region. Multiple serotypes circulate each vector season with the occurrence of different serotypes depending largely on herd-immunity. Indigenous sheep breeds, cattle and wild ruminants are frequently infected but rarely demonstrate clinical signs, whereas improved European sheep breeds are most susceptible. The immunization of susceptible sheep remains the most effective and practical control measure against BT. In order to protect sheep against multiple circulating serotypes, three pentavalent attenuated vaccines have been developed. Despite the proven efficacy of these vaccines in protecting sheep against the disease, several disadvantages are associated with their use in the field.

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 was genetically closer to AHSV than EEV. This study confirmed the presence of three distinct S10 phylogenetic clades (alpha, beta and gamma). Some serotypes (6, 8 and 9 in alpha; 3 and 7 in beta; 2 in gamma) were restricted to a single clade, while other serotypes (1, 4 and 5) clustered into both the alpha and gamma clades. Strong purifying selection was evident and a constant molecular clock was inappropriate. The S10 gene is the second most variable gene of the AHSV genome and the use of S10 in molecular epidemiology was illustrated by an AHS outbreak in the Western Cape in 2004. It was shown that two separate AHSV were circulating in the area, even though AHSV serotype 1 was the only isolate from the outbreak. The small size of the gene (755-764 bp) and conserved terminal regions facilitate easy and quick sequencing. The establishment of an S10 sequence database is important for characterizing outbreaks of AHS. It will be an essential resource for elucidating the epidemiology of AHS.

BLACK-BACKED JACKAL EXPOSURE TO RABIES VIRUS, CANINE DISTEMPER VIRUS, AND BACILLUS ANTHRACIS IN ETOSHA NATIONAL PARK, NAMIBIA

Canine distemper virus (CDV) and rabies virus (RABV) occur worldwide in wild carnivore and domestic dog populations and pose threats to wildlife conservation and public health. In Etosha National Park (ENP), Namibia, anthrax is endemic and generates carcasses frequently fed on by an unusually dense population of black-backed jackals (Canis mesomelas). Using serology, phylogenetic analyses (on samples obtained from February 2009–July 2010), and historical mortality records (1975–2011), we assessed jackal exposure to Bacillus anthracis (BA; the causal bacterial agent of anthrax), CDV, and RABV. Prevalence of antibodies against BA (95%, n=86) and CDV (71%, n=80) was relatively high, while that of antibodies against RABV was low (9%, n=81). Exposure to BA increased significantly with age, and all animals >6 mo old were antibody-positive. As with BA, prevalence of antibodies against CDV increased significantly with age, with similar age-specific trends during both years of the study. No significant effect of age was found on the prevalence of antibodies against RABV. Three of the seven animals with antibodies against RABV were monitored for more than 1 yr after sampling and showed no signs of active infection. Mortality records revealed that rabid animals are destroyed nearly every year inside the ENP tourist camps. Phylogenetic analyses demonstrated that jackal RABV in ENP is part of the same transmission cycle as other dog-jackal RABV cycles in Namibia.

Infection with Ovine Herpesvirus 2 in Norwegian Herds with a History of Previous Outbreaks of Malignant Catarrhal Fever

Infection with Ovine herpesvirus 2 (OvHV-2) in healthy cattle, swine, sheep, and goats was investigated on 43 selected Norwegian farms; of which, 41 (95%) had experienced outbreaks of malignant catarrhal fever (MCF) in cattle and/or swine during the preceding 5 years. Two of the farms had no history of MCF and were included for control purposes. Blood samples from 384 cattle, 40 sows, 75 sheep, and 4 goats were examined for OvHV-2 by polymerase chain reaction assay (PCR) and for antibodies using a competitive inhibition enzyme-linked immunosorbent assay (ciELISA). All samples were also tested for antibodies reactive to Alcelaphine herpesvirus 1 with an indirect fluorescent antibody test (IFAT). All but 4 of the sheep and all 4 goats tested positive with 1 or more of the tests. Eighty-nine (25%) of the cattle and 17 (43%) of the swine on the farms with previous MCF outbreaks tested positive with 1 or more of the tests. On 22 of the farms, at least 1 bovine tested positive with ciELISA and/or PCR, whereas 8 other farms had test-positive cattle with IFAT only. The 2 control farms yielded no positive results with any of the tests. Four of the farms had swine that tested positive with PCR, but none with ciELISA, whereas 4 other farms had test-positive swine with IFAT only. The prevalence of infection in cattle and swine seemed not to be influenced either by their age or the degree of contact with the sheep and goats.

Transplacental infection in goats experimentally infected with a European strain of bluetongue virus serotype 8

The capability of the recently emerged European strain of bluetongue virus serotype 8 (BTV-8) to cross the ruminant placenta has been established in experimental and field studies in both sheep and cattle. Seroprevalence rates in goats in North-Western Europe were high during the recent outbreak of BTV-8; however the capability of the virus to infect goats through the transplacental route has not been established. In the present study, four Saanen goats were inoculated with the European strain of BTV-8 at 62 days of gestation; this resulted in mild clinical signs, however gross lesions observed post mortem were more severe. Viral RNA was detected by real-time RT-PCR in blood and tissue samples from three fetuses harvested from two goats at 43 days post infection. Conventional RT-PCR and genome sequencing targeting viral segment 2 confirmed infection of brain tissue with BTV-8 in two of these fetuses. In total, five of six fetuses demonstrated lesions that may have been associated with transplacental infection with BTV. Infected fetuses did not demonstrate neurological lesions. Low viral RNA concentrations in fetal blood and tissue further suggest that the infected fetuses would probably not have been born viraemic. The implications of these findings with regards to the epidemiology and overwintering of BTV-8 in Europe remains unclear.

Genetic analysis of the VP2-encoding gene of canine parvovirus strains from Africa

Since the emergence of canine parvovirus type-2 (CPV-2) in the early 1970s, it has been evolving into novel genetic and antigenic variants (CPV-2a, 2b and 2c) that are unevenly distributed throughout the world. Genetic characterization of CPV-2 has not been documented in Africa since 1998 apart from the study carried out in Tunisia 2009. A total of 139 field samples were collected from South Africa and Nigeria, detected using PCR and the full length VP2-encoding gene of 27 positive samples were sequenced and genetically analyzed. Nigerian samples (n=6), South Africa (n=19) and vaccine strains (n=2) were compared with existing sequences obtained from GenBank. The results showed the presence of both CPV-2a and 2b in South Africa and only CPV-2a in Nigeria. No CPV-2c strain was detected during this study. Phylogenetic analysis showed a clustering not strictly associated with the geographical origin of the analyzed strains, although most of the South African strains tended to cluster together and the viral strains analyzed in this study were not completely distinct from CPV-2 strains from other parts of the world. Amino acid analysis showed predicted amino acid changes.

A review of experimental infections with bluetongue virus in the mammalian host

Abstract Experimental infection studies with bluetongue virus (BTV) in the mammalian host have a history that stretches back to the late 18th century. Studies in a wide range of ruminant and camelid species as well as mice have been instrumental in understanding BTV transmission, bluetongue (BT) pathogenicity/pathogenesis, viral virulence, the induced immune response, as well as reproductive failures associated with BTV infection. These studies have in many cases been complemented by in vitro studies with BTV in different cell types in tissue culture. Together these studies have formed the basis for the understanding of BTV-host interaction and have contributed to the design of successful control strategies, including the development of effective vaccines. This review describes some of the fundamental and contemporary infection studies that have been conducted with BTV in the mammalian host and provides an overview of the principal animal welfare issues that should be considered when designing experimental infection studies with BTV in in vivo infection models. Examples are provided from the authors’ own laboratory where the three Rs (replacement, reduction and refinement) have been implemented in the design of experimental infection studies with BTV in mice and goats. The use of the ARRIVE guidelines for the reporting of data from animal infection studies is emphasized.

DETECTION OF FELINE CORONAVIRUS INFECTION IN SOUTHERN AFRICAN NONDOMESTIC FELIDS

Feline coronavirus (FCoV) infects members of the Felidae family with results ranging from seroconversion with no disease to fatal feline infectious peritonitis (FIP). Infection of non-domestic felids with FCoV is of concern, particularly in endangered populations such as cheetahs (Acinonyx jubatus). In this investigation, we tested 342 animals in the Republic of South Africa and Namibia, including 140 animals from wild populations, for evidence of FCoV infection by serology and/or reverse transcription/nested polymerase chain reaction (RT/nPCR) on feces from 1999 through 2001. Past or current infection was evaluated. Of these, 195 animals had evidence of infection and included 41 animals from wild populations. Serology (indirect immunofluorescence) did not always correlate with viral RNA detection, as seronegative animals were occasionally virus-positive, while many seropositive animals were not shedding virus. Serology indicated the infecting virus was most closely related to type I FCoV. Antibody levels in the majority of animals were low, even in those actively infected. Ten of 48 animals tested at more than one time point by RT/nPCR were shedding virus at multiple time points possibly indicating persistent infection. Infection in free-ranging animals was also notable, as over a quarter of the free-ranging animals tested had evidence of current or previous FCoV infection. Testing by serology and RT/nPCR is recommended for screening for FCoV infection.

SENSITIVITY AND SPECIFICITY OF A NESTED POLYMERASE CHAIN REACTION FOR DETECTION OF LENTIVIRUS INFECTION IN LIONS (PANTHERA LEO)

Abstract Feline immunodeficiency virus (FIV) is a lentivirus in the Retroviridae family that causes lifelong infection in domestic cats. The lentivirus of African lions (Panthera leo), referred to as FIVple, is endemic in certain lion populations in eastern and southern Africa. Lentivirus infection leads to immunologic dysfunction and immunosuppressive disease in domestic cats; however, little is known about the pathogenic effects of infection in lions, nor about the epidemiologic impact on free-ranging and captive populations. Whole blood and serum samples were collected opportunistically from free-ranging lions in Kruger National Park, Republic of South Africa (RSA). Whole blood and serum samples were also collected from captive wild lions in the RSA. A nested polymerase chain reaction (PCR) assay for detection of FIV was performed on all whole blood samples. In addition, serum samples were tested for cross-reactive antibodies to domestic feline lentivirus antigens and puma lentivirus synthetic envelope peptide antigen. The PCR assay successfully amplified the lion lentivirus from African lions. The relative sensitivity and relative specificity were 79% and 100%, respectively, and the positive and negative predictive values were 100% and 67%, respectively. This research represents the first study to compare genetic material with antibody-based methods of lentivirus detection on lions in RSA. Using PCR as an additional diagnostic test for FIV in lions will increase screening sensitivity and will allow viral characterization among circulating isolates and monitoring of changes in the viral epidemiology within geographic regions and populations over time.