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1.
The aims of this investigation were to determine the prevalence of ovine herpesvirus type 2 (OvHV-2) (the causative agent of malignant catarrhal fever) infection in cattle, the carrier status of sheep and goats, and to define the pattern of acquisition of OvHV-2 in lambs under natural flock conditions in Kashmir, India. None of the buffy coat samples from 21 lambs contained OvHV-2 DNA sequences up to 28 days after birth, only one lamb had sequences of OvHV-2 DNA as early as 29 days after birth, and they were detected in the other 20 lambs when they were between 43 and 94 days of age. Sequences of OvHV-2 DNA were detected in buffy coat samples from 28 (85 per cent) of 33 adult sheep and in 16 (61 per cent) of 26 samples from adult goats by hemi-nested PCR. Seventeen (31 per cent) of 55 cattle with malignant catarrhal fever-like clinical signs had sequences of OvHV-2 DNA in their blood, and nine of the 17 died, all of them during the months of April to November, between November 2002 and March 2004. No clinical cases of sheep-associated malignant catarrhal fever was recorded during the months of December to March. The overall prevalence of OvHV-2 infection in the cattle in the region was estimated to be less than 1 per cent.  相似文献   

2.
July 2004, a cow with clinical signs of ovine herpesvirus type-2 infection which is known as sheep associated malignant catarrhal fever (SA-MCF) was reported in Samsun Province in Turkey. Blood samples were collected from the suspected cow, 10 sheep housed with it, and from 150 healthy sheep and 29 healthy cattle randomly selected from different places in Samsun Province. Nested polymerase chain reaction (n-PCR) was used to detect ovine herpesvirus type-2 (OvHV-2) DNA in the suspected cow and competitive- ELISA (c-ELISA) kits were used to detect antibodies against OvHV-2. The suspected cow was found to be n-PCR positive and c-ELISA negative. The serological results were as follows: All 10 (100%) of sheep housed with the suspected cow and 18 of 29 (62%) of the randomly selected cattle were found seropositive. All 150 randomly selected healthy sheep were seronegative. The overall percentage of seropositivity was 14.7% (28/190). OvHV-2 DNA was detected in the peripheral blood leucocyte (PBL) samples of the cow and of the 10 sheep housed with the suspected cow.  相似文献   

3.
Infection of clinically susceptible ruminants, including domesticated cattle and American bison, with ovine herpesvirus 2 (OvHV-2) can result in the fatal lymphoproliferative and vasculitis syndrome known as malignant catarrhal fever (MCF). A reliable experimental infection model is needed to study the pathogenesis of MCF and to develop effective vaccination strategies to control the disease. An experimental aerosol infection model using sheep, the natural carriers of OvHV-2, has been developed (Taus et al., 2005). Using the protocol and OvHV-2 inoculum established in the previous study, eight calves were nebulized with four different doses of OvHV-2 in nasal secretions from infected sheep. Two control calves were nebulized with nasal secretions from uninfected sheep. Infection status of all calves was monitored using competitive inhibition ELISA, PCR and clinical parameters. Six of eight nebulized calves became infected with OvHV-2. One calf receiving the highest dose of virus developed typical clinical, gross and histological changes of MCF. This study showed that nasal secretions collected from sheep experiencing OvHV-2 shedding episodes were infectious for cattle and capable of inducing MCF. The data also indicate that cattle are relatively resistant to disease following infection. The use of more susceptible species as experimental animal models, such as bison and selected cervid species should be examined.  相似文献   

4.
The assumption that sheep carry ovine herpesvirus-2 (OvHV-2), the causative agent of sheep-associated malignant catarrhal fever (SA-MCF), is widely accepted, albeit OvHV-2 has not been isolated. We attempted experimental contact transmission of MCF from Japanese sheep persistently infected with OvHV-2 to Japanese deer (Cervus nippon) and cattle. In Experiment 1, a deer was kept in close quarters with an infected ewe. In Experiment 2, a second deer was kept with the same ewe. In Experiment 3, two cows were each kept with two infected wethers. In Experiment 1, the deer developed clinical signs at 138 days after first contact and then died. OvHV-2 genes by polymerase chain reaction (PCR) and fluorescent antibodies to Alcelaphine herpesvirus-1 were detected in the affected deer. Moreover, sequences of PCR products (423bp), obtained by amplification of materials from the sheep and from the affected deer, coincided. These results clearly confirmed that the sheep was a carrier of OvHV-2, and that this virus had induced SA-MCF in a deer. In other experiments, no OvHV-2 infection occurred in deer and cattle during the 6-18 months periods of contact, though viral genes were detected in the nasal swabs and white blood cells of the sheep. To our knowledge, this is the first report on successful experimental transmission of MCF from OvHV-2-infected sheep to deer.  相似文献   

5.
Malignant catarrhal fever (MCF), a frequently fatal herpesviral disease primarily of ruminant species, has been sporadically reported in pigs. All cases of naturally occurring porcine MCF reported to date have been linked to ovine herpesvirus 2 (OvHV-2), a gammaherpesvirus in the genus Macavirus carried by sheep. Experimental induction of MCF by aerosolization of the virus in nasal secretions collected from infected sheep has been successful in bison, cattle and rabbits. The goals of this study were to determine the susceptibility of pigs to MCF following experimental intranasal inoculation of OvHV-2, and to characterize the disease. Twelve pigs in four groups were nebulized with 10(5), 10(6), 10(7), or 10(8) DNA copies of OvHV-2 from sheep nasal secretions. Three control pigs were nebulized with nasal secretions from uninfected sheep. Three additional pigs were inoculated intravenously with 10(7) DNA copies of OvHV-2 to evaluate this route of infection with cell-free virus. Seven of twelve intranasally challenged pigs became infected with OvHV-2. Five of these seven, all in higher dose groups, developed MCF. Lesions resembled those reported in natural cases of porcine MCF. The most striking and consistent histological lesions were in trachea, lung, kidney and brain. These comprised mucopurulent tracheitis, interstitial pneumonia, necrotizing arteritis-periarteritis, and nonpurulent meningoencephalitis. No infection was established in the intravenously challenged or control groups. The study showed that MCF can be experimentally induced in pigs by aerosol challenge using sheep nasal secretions containing OvHV-2. Domestic pigs are a natural clinically susceptible host for sheep-associated MCF. They represent a useful, cost-effective model for MCF research.  相似文献   

6.
Malignant catarrhal fever (MCF) is a frequently fatal lymphoproliferative disease syndrome primarily of ruminant species, caused by gammaherpesviruses in the genus Macavirus. Ovine herpesvirus 2 (OvHV-2), carried by sheep, causes sheep-associated MCF worldwide, while Alcelaphine herpesvirus 1 (AlHV-1), carried by wildebeest, causes wildebeest-associated MCF, mainly in Africa. Diseases in rabbits can be induced by both viruses, which are clinically and pathologically similar; however, recent studies revealed different expression of viral genes associated with latency or lytic replication during clinical disease between the two viruses. In this study, we further characterized experimentally induced MCF in rabbits by nebulization with OvHV-2 from sheep nasal secretions to elucidate the course of viral replication, along with in vivo incorporation of 5-Bromo-2'-Deoxyuridine (BrdU), to evaluate lymphoproliferation. All six rabbits nebulized with OvHV-2 developed MCF between 24 and 29 days post infection. OvHV-2 DNA levels in peripheral blood leukocytes (PBL) remained undetectable during the incubation period and increased dramatically a few days before onset of clinical signs. During the clinical stage, we found that predominantly lytic gene expression was detected in PBL and tissues, and both T and B cells were proliferating. The data showed that the viral gene expression profile and lymphoproliferation in rabbits with OvHV-2 induced MCF were different from that in rabbits with AlHV-1 induced MCF, suggesting that OvHV-2 and AlHV-1 may play a different role in MCF pathogenesis.  相似文献   

7.
Sheep-associated malignant catarrhal fever (SA-MCF), a frequently fatal disease primarily of certain ruminants, is caused by ovine herpesvirus 2 (OvHV-2). Molecular diagnosis of SA-MCF in affected animals has relied on detection of OvHV-2 DNA using a nested PCR, which has significant potential for amplicon contamination as a routine method in diagnostic laboratories. In this report, a nonnested and a previously developed real-time PCR were validated for detection of OvHV-2 DNA in samples from clinically affected animals. Three sets of blood or tissue samples were collected: 1) 97 samples from 97 naturally affected animals with evidence of clinical SA-MCF; 2) 200 samples from 8 animals with experimentally induced SA-MCF; and 3) 100 samples from 100 animals without any evidence of clinical SA-MCF. Among 97 positive samples defined by nested PCR from clinically affected animals, 95 (98%) were positive by nonnested PCR and 93 (96%) were positive by real-time PCR, respectively. One hundred percent of the samples from the animals with experimentally induced MCF were positive by real-time PCR, while 99% were positive by nonnested PCR. Neither nonnested PCR nor real-time PCR yielded a positive result on any of the 100 nested PCR-negative samples from animals without evidence of clinical MCF. The data confirmed that both nonnested and real-time PCR maintained high specificity and sensitivity for the detection of OvHV-2 DNA in clinical samples.  相似文献   

8.
Malignant catarrhal fever (MCF) is a usually fatal infectious disease of cattle with global distribution. Based on the recent introduction of a diagnostic PCR assay and a competitive inhibition ELISA (ciELISA) epidemiological data were collected on field cases in Switzerland. Throughout a three-year period, an MCF incidence of 0.6@1000 was observed, with a gradient of cases from Eastern to Western Switzerland. While the cantons Wallis, Vaud and Geneva reported no and the remaining western cantons only reported a few cases, the highest incidence was observed in the cantons Appenzell Innerrhoden, Lucern, Glarus, Grison, St. Gallen, Schwyz, and Thurgau. MCF occurred seasonally and an age-related clustering was also observed. About 50% of all cases and all outbreaks with more than one animal in a single herd occurred between April and June. Animals between six months and two years were strongly over represented. Observations on four surviving cattle showed that the outcome of the disease is not invariably fatal and that these persistently infected cows can produce healthy negative calves. Investigations on the aetiology indicate that the main reservoir for OvHV-2 is in sheep and possibly goats, while cattle do not normally harbor the virus. An OvHV-2 negative sheep herd was raised from lambs, which were reared colostrum-free and in isolation from their mothers. The success rate clearly indicated that vertical intrauterine infection is not the main mode of transmission among sheep. Therefore, horizontal, seasonally occurring transmission of OvHV-2 among sheep has to be assumed.  相似文献   

9.
A malignant catarrhal fever (MCF)-like disease was induced experimentally in 3 sheep after aerosol inoculation with ovine herpesvirus-2 (OvHV-2). Each of 3 OvHV-2-negative sheep was nebulized with 2 ml of nasal secretions containing approximately 3.07 X 10(9) OvHV-2 DNA copies from a sheep experiencing an intensive viral-shedding episode. Ovine herpesvirus-2 DNA became detectable by polymerase chain reaction in the peripheral blood leukocytes of all 3 sheep within 3 days, and all 3 seroconverted between 6 and 8 days postinfection (PI). The sheep developed clinical signs, with copious mucopurulent nasal discharge and fever around 14 days PI. One of the 3 clinically affected sheep was euthanized at 18 days PI. Major lesions at necropsy were multifocal linear erosions and ulcers in mucosa of the cheeks, tongue, pharynx, and proximal esophagus and mild disseminated pneumonia. Microscopically, there was extensive moderate superficial histiocytic-lymphocytic rhinitis with epithelial dissociation and degeneration. Moderate multifocal histiocytic bronchointerstitial pneumonia was associated with loss of terminal bronchiolar epithelium. Lymphocytic vasculitis was present only in the lung. The remaining 2 sheep recovered clinically, approximately 25 days PI. The study revealed that clinical signs and lesions resembling MCF can develop when uninfected sheep are exposed to a high dose of aerosolized OvHV-2.  相似文献   

10.
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11.
About 90% of bovine malignant catarrhal fever (BMCF) PCR-positive cases in South Africa are caused by alcelaphine herpesvirus-1 (AlHV-1) and the other 10% by ovine herpesvirus-2 (OvHV-2). The prevalence of OvHV-2 in different sheep breeds in South Africa was determined in order to investigate whether the lower incidence of BMCF caused by OvHV-2 in comparison with AlHV-1 can be ascribed to a low incidence of the virus in sheep. A single-tube hemi-nested PCR was developed, evaluated and applied to detect OvHV-2 DNA. The prevalence of the virus in 4 sheep breeds from various regions in South Africa was shown to be 77%. No statistically significant difference was found amongst the sheep breeds tested.  相似文献   

12.
Sheep-associated malignant catarrhal fever (MCF) due to infection with ovine herpesvirus 2 (OvHV-2) is common in commercial herds of American bison ( Bison bison). Inability to propagate OvHV-2 in vitro has been a constraint on experimental studies of the disease. We sought to establish whether nasal secretions from sheep that shed OvHV-2 might induce the disease in bison and to define a minimum challenge dose. Fourteen bison were nebulized with sheep nasal sections containing 10(3)-10(7) OvHV-2 deoxyribonucleic acid (DNA) copies. Most challenged bison (11/14, 78.6%) developed clinical signs at 29-52 days postnebulization (DPN). The mean incubation time was 42.18 (+/-7.33 SD) DPN. Using real-time polymerase chain reaction, we detected OvHV-2 DNA in peripheral blood leukocytes at 21-31 DPN. All bison that developed MCF had antibodies against the MCF group viruses. Gross and histologic lesions were typical of the acute disease. There was no morphologic evidence of a dose-related difference in the severity or distribution of lesions. This is the first successful reproduction of MCF in bison using a nasal route of exposure. Experimentally challenged bison are more susceptible to MCF, compared with experimentally challenged domestic cattle in a previous experiment. Bison are a pertinent ruminant species in which the pathogenesis of the disease can be investigated.  相似文献   

13.
During late 2001 and early 2002, a mixed species wildlife park in North Carolina experienced an acute outbreak of morbidity and mortality in Pere David's deer (Elaphurus davidianus), axis deer (Axis axis), blackbuck antelope (Antelope cervicapra), white-tailed deer (Odocoileus virginianus), and Rocky Mountain elk (Cervus elaphus). Clinical signs varied from fulminant disease, progressing from depression to bloody scours to death in fewer than 4 days in Pere David's deer, to a more protracted form of disease, ranging from 2 wk to 3 mo, in axis deer. In moribund axis deer, high levels of anti-malignant catarrhal fever (MCF) virus antibody by competitive-inhibition enzyme-linked immunosorbent assay were detected. Ovine herpesvirus 2 (OvHV-2) DNA was detected in peripheral blood leukocytes of the affected axis deer. No other MCF viruses were detected. Retrospective examination of frozen tissue samples from the affected Pere David's deer and blackbuck antelope also confirmed the presence of OvHV-2 DNA. Initial control efforts were directed at preventing further deaths of clinically susceptible animals by removing MCF virus reservoir species, particularly ovine species. The most prevalent ovine species in the wildlife park was mouflon sheep (Ovis musimon). All sheep were removed from the park by June 2002, and the last MCF death occurred in October 2002. Since mouflon sheep had been a prominent attraction in the wildlife park, the owner wanted a means to reintroduce this species to the park. Derivation of OvHV-2-uninfected mouflon lambs was undertaken using the previously described program for production of OvHV-2-free sheep (Ovis ovis). The rederived MCF virus-negative mouflon sheep were introduced into the park in approximately January 2004. As of December 2007, no further cases of MCF have occurred since the removal of OvHV-2-positive mouflon sheep and reintroduction of the virus-free lambs. This paper describes the successful management and control of MCF in a densely populated mixed species animal park.  相似文献   

14.
OBJECTIVE: To monitor ovine herpesvirus type 2 (OvHV-2) infection status and the association between OvHV-2 infection and development of clinical signs of malignant catarrhal fever (MCF) in cattle. DESIGN: Longitudinal study. ANIMALS: 30 mature adult cows and 18 cattle submitted for necropsy. PROCEDURE: Blood and milk samples were collected at monthly intervals from 30 adult cows for 20 consecutive months. Nasal and ocular swab specimens were also collected during months 9 through 20. Polymerase chain reaction (PCR) assay for detection of OvHV-2 was performed on blood, milk, nasal swab, and ocular swab specimens. Competitive inhibition ELISA (CI-ELISA) for detection of antibodies against MCF viruses was performed on serum samples obtained prior to study initiation and monthly during the last 12 months. Tissues obtained from herdmates without clinical signs of MCF that were submitted for necropsy were analyzed for OvHV-2 DNA via PCR assay for possible sites of latency. RESULTS: Initially, 8 of 30 cows had positive CI-ELISA results. Seroconversion was detected in 4 cows. Ovine herpesvirus type 2 DNA was intermittently detected in blood, milk, nasal secretions, or ocular secretions from 17 of 30 cows. Twenty-one cows had positive CI-ELISA or PCR assay results. No cattle in the study developed clinical signs of MCF. Results of PCR assays performed on tissue samples from 2 of 18 animals submitted for necropsy were positive for OvHV-2. CONCLUSIONS AND CLINICAL RELEVANCE; OvHV-2 infection can occur in cattle without concurrent development of clinical MCF. Ovine herpesvirus type 2 DNA was detected intermittently, suggesting fluctuating viral DNA loads or reinfection in subclinical cattle. A definitive site of latency was not identified from tissues obtained during necropsy.  相似文献   

15.
An outbreak of the sheep-associated form of malignant catarrhal fever (MCF) in a Finnish sow herd was diagnosed by histopathology and confirmed by PCR. Several gilts and sows were suffering from high fever and anorexia and had aborted, and six of them had died. Typical signs of lymphoproliferation and vasculitis were observed histologically in several tissues, including the uterus. Ovine herpesvirus-2 (OvHV-2) was detected by PCR in two sows. Sequences of the OvHV-2 tegument protein gene obtained from the sows and from three cases of sheep-associated mcf in Finnish cattle were compared and found to be identical. These are the first confirmed cases of mcf in pigs in Finland.  相似文献   

16.
Malignant catarrhal fever (MCF)-like disease was diagnosed at postmortem in 2 Stone's sheep (Ovis dalli stonei). On gross examination, the predominant abnormality in both sheep was severe perirenal hemorrhage and multiple renal infarcts. Microscopically, there was severe, multisystemic lymphocytic arteritis. Both sheep were positive for Ovine herpesvirus 2 (OvHV-2) on polymerase chain reaction, and partial sequencing of the viral DNA polymerase genes from the 2 sheep revealed >99% homology, with 96% similarity to the reference GenBank OvHV-2 viral sequence. Based on the histological lesions, polymerase chain reaction results, and viral DNA polymerase gene sequencing, a diagnosis of OvHV-2-mediated MCF was made. Massive perirenal hemorrhage has not been described previously as a manifestation of MCF.  相似文献   

17.
Malignant catarrhal fever (MCF) is a fatal lymphoproliferative disease of cattle and other ungulates caused by the ruminant γ-herpesviruses alcelaphine herpesvirus 1 (AlHV-1) and ovine herpesvirus 2 (OvHV-2). These viruses cause inapparent infection in their reservoir hosts (wildebeest for AlHV-1 and sheep for OvHV-2), but fatal lymphoproliferative disease when they infect MCF-susceptible hosts, including cattle, deer, bison, water buffalo and pigs. MCF is an important disease wherever reservoir and MCF-susceptible species mix and currently is a particular problem in Bali cattle in Indonesia, bison in the USA and in pastoralist cattle herds in Eastern and Southern Africa.MCF is characterised by the accumulation of lymphocytes (predominantly CD8+ T lymphocytes) in a variety of organs, often associated with tissue necrosis. Only a small proportion of these lymphocytes appear to contain virus, although recent results with virus gene-specific probes indicate that more infected cells may be present than previously thought. The tissue damage in MCF is hypothesised to be caused by the indiscriminate activity of MHC-unrestricted cytotoxic T/natural killer cells. The pathogenesis of MCF and the virus life cycle are poorly understood and, currently, there is no effective disease control.Recent sequencing of the OvHV-2 genome and construction of an AlHV-1 bacterial artificial chromosome (BAC) are facilitating studies to understand the pathogenesis of this extraordinary disease. Furthermore, new and improved methods of disease diagnosis have been developed and promising vaccine strategies are being tested. The next few years are likely to be exciting and productive for MCF research.  相似文献   

18.
In a double sense, the ovine gamma herpesvirus type 2 (OvHV-2) is a virus in sheep's skin. Not only is it present world wide in all sheep breeds but also it causes malignant catarrhal fever (MCF) in cattle pigs, elk, and bison. OvHV-2 cannot be propagated in cell culture. Therefore, new results from OvHV-2 research are based on molecular techniques and may be summarized as follows. OvHV-2 is transmitted by respiratory routes as well as by sexual intercourse. Lambs are infected within the first few months of life. Leucocytes, primarily latently infected lymphocytes, are responsible for disseminating the virus over the entire organism. On rare occasions, virus particles could be visualized by electron microscopy in explanted lymphocyte cultures. Structural antigens were detected by immunohistology in M-cells of diseased rabbits. Immunologically and cell biologically active genes have been detected on the viral genome.The products arising from those are thought to fine balance, the number of latently infected cells in sheep and to keep them alive without causing harm. Thus, it seems that this balance has been found through co-evolution, favoring both virus and natural host. In contrast, other host species that were exclude from the process of co-evolution, are bound to fall from MCF.  相似文献   

19.
《Veterinary microbiology》2015,175(2-4):349-355
Ovine herpesvirus-2 (OvHV-2) is the etiological agent of sheep-associated malignant catarrhal fever (SA-MCF), a fatal lymphoproliferative disease of many species in the order Artiodactyla. Development of a vaccine is critical to prevent mortality. Because OvHV-2 has not been cultured in vitro, SA-MCF research is hindered by the lack of in vitro tools to study viral constituents and specific host immune responses. As an alternative, in this study the neutralizing activity of antibodies against OvHV-2 glycoproteins gB and gH/gL was evaluated in vivo using rabbits. OvHV-2-specific antibodies were developed in rabbits by immunization using biolistic delivery of plasmids expressing the genes of interest. A lethal dose of OvHV-2 was incubated with the antisera and then nebulized into rabbits. Virus neutralization was assessed by measuring infection parameters associated with the virus infectious dose. Anti-gB or anti-gH/gL antibodies alone blocked infection in five out of six rabbits (83%), while a combination of anti-gB and anti-gH/gL antibodies protected all six rabbits (100%) from infection. These results indicate that antibodies to OvHV-2 gB and gH/gL are capable of neutralizing virions, and consequently, reduce virus infectivity and prevent SA-MCF in rabbits. Thus, OvHV-2 gB and gH/gL are suitable targets to be tested in a SA-MCF vaccine aimed at stimulating neutralizing antibody responses.  相似文献   

20.
A recently developed competitive PCR for ovine herpesvirus 2 (OvHV-2) was used to examine the levels of viral DNA in nasal secretions and peripheral blood leukocytes (PBL) of lambs and adult sheep. Viral DNA first appeared in the PBL of most lambs after about 3 months of age and the levels remained relatively constant thereafter. In most of the lambs (83%, n=12), viral DNA was undetectable by PCR in nasal secretions prior to 5 months of age. A dramatic rise of OvHV-2 DNA levels in the nasal secretions occurred starting at 5-6 months of age, which peaked at approximately 7 months. The highest level recorded in lamb nasal secretions was 7.5x10(8)copies/2microg DNA which were 75,000-100,000-fold higher than the levels in PBL of the same lambs. In adult sheep (n=10), the viral DNA levels in both PBL and nasal secretions were relatively stable over the 13-month period of the study, which included a lambing season. The data strongly suggest that neonatal lambs are not an important source for the transmission of OvHV-2 to clinically susceptible species, and that the nasal cavity is an important portal for shedding of infectious OvHV-2 in sheep. Furthermore, this study failed to identify a seasonal pattern in levels of viral DNA in nasal secretions or PBL of adult sheep that would provide a basis for the traditionally held belief that clinical cases of malignant catarrhal fever are significantly associated with lambing ewes.  相似文献   

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