Ibex-Associated Malignant Catarrhal Fever in Duikers (Cephalophus Spp).

Eight duikers, representing 3 different species cohoused in a single zoological collection, died in a 10-month period. Black, red-flanked, and yellow-backed duikers were affected, appearing clinically with a combination of anorexia, diarrhea, ataxia, tremors, and/or stupor, followed by death within 72 hours of onset of clinical signs. Consistent gross findings were pulmonary ecchymoses (8/8), generalized lymphadenomegaly (6/8), ascites (5/8), and pleural effusion (4/8). Dense lymphocyte infiltrates and arteritis affected numerous tissues in most animals. Ibex-associated malignant catarrhal fever (MCF) viral DNA was detected in all cases by polymerase chain reaction and in situ hybridization. Identical ibex-MCF virus sequence was detected in spleen of a clinically healthy ibex (Capra ibex) housed in a separate enclosure 35 meters away from the duikers.

Detection and molecular characterization of naturally transmitted sheep associated malignant catarrhal fever in cattle in India.

Malignant catarrhal fever (MCF) is a fatal herpesvirus infection of domestic and wild ruminants, with a short and dramatic clinical course characterized primarily by high fever, severe depression, swollen lymph nodes, salivation, diarrhea, dermatitis, neurological disorders, and ocular lesions often leading to blindness. In the present study, fatal clinical cases of sheep associated malignant catarrhal fever (SA-MCF) were identified in cattle in the state of Karnataka. These cases were initially presented with symptoms of diarrhea, respiratory distress, conjunctivitis, and nasal discharges. Laboratory diagnosis confirmed the detection of ovine herpesvirus-2 (OvHV-2) genome in the peripheral blood samples of two ailing animals. The blood samples collected subsequently from sheep of the neighboring areas also showed presence of OvHV-2 genome indicating a nidus of infection in the region. The positive test results were further confirmed by nucleotide sequencing of the OIE approved portion of tegument gene as well as complete ORF8 region of the OvHV-2 genome. Phylogenetic analysis based on the sequence of the latter region indicated close genetic relationship with other OvHV-2 reported elsewhere in the world.

Ibex-associated malignant catarrhal fever-like disease in a group of bongo antelope (Tragelaphus eurycerus).

A private zoological facility experienced an outbreak of malignant catarrhal fever (MCF) in 3 bongo antelope (Tragelaphus eurycerus). All cases were periparturient bongos that presented acutely anorectic beginning ~6 weeks after being housed with a Nubian ibex. Disease quickly progressed to respiratory distress and death within 24-72 hours of onset of clinical signs. Consistent gross findings in affected bongos were pulmonary edema and small pale tan foci in the livers. Histological lesions included a nonsuppurative vasculitis in multiple tissues, which is well recognized in MCF, but additionally included necrotizing cholangiohepatitis and neutrophilic, necrotizing myocarditis. Ibex-associated viral DNA was detected by polymerase chain reaction and was identical in sequence whether derived from bongos or ibex. The sequence closely matched an MCF viral DNA fragment that had been amplified from an ibex and bongo in a previous case report.

Sheep-associated malignant catarrhal fever in free-ranging moose (Alces alces) in Saskatchewan, Canada.

Malignant catarrhal fever (MCF) is a sporadic disease of artiodactyls caused by several viruses in the Gammaherpesvirinae. We report two cases of MCF in free-living moose (Alces alces) from Saskatchewan. One was a thin, dehydrated, adult male found recumbent in 2006. At necropsy, ulcers were found in the intestine, bladder, and corneas. Microscopically, there was lymphocytic vasculitis and perivasculitis in many organs with infrequent fibrinoid necrosis. Ovine herpes virus-2 (OHV-2) was identified by polymerase chain reaction. A segment of the herpesviral DNA polymerase gene was 99% identical to published OHV-2 sequences. During a retrospective search of earlier cases, a female moose with lymphoplasmacytic meningoencephalitis examined in 2003 was identified and OHV-2 was amplified from paraffin-embedded tissues from this animal. We believe this to be the first description of MCF in free-ranging moose in North America. Infection requires contact with infected sheep or goats, and MCF in moose may become more prevalent as moose distribution continues to expand into agricultural prairie.

Long distance spread of malignant catarrhal fever virus from feedlot lambs to ranch bison.

Malignant catarrhal fever (MCF) caused by OvHV-2 occurred in ranch bison herds separated by significant distances from feedlot lambs. Mortality rates correlated with distances: 17.5%, 6.1%, and 0.43% at approximately 1.6, 4.2, and 5.1 km, respectively. The study further defines the importance of distance of species separation for MCF control.

Gammaherpesvirus carrier status of black wildebeest (Connochaetes gnou) in South Africa.

Malignant catarrhal fever (MCF) is an economically important disease primarily of domestic cattle with a high case fatality rate. It is caused by either alcelaphine herpesvirus type 1 (AlHV-1) or ovine herpesvirus type 2 (OvHV-2). The major reservoir host of AlHV-1 is the blue wildebeest (Connochaetes taurinus), but it is generally accepted that the black wildebeest (Connochaetes gnou) is also a reservoir host. No viral studies in the black wildebeest have been reported and the carrier status of black wildebeest has not been documented. Specimens were collected from several game farms and conservation areas in central South Africa representing the geographical area historically linked to the natural habitat of the black wildebeest. Specimens were obtained from 304 black wildebeest of different ages and sex, as well as 51 black wildebeest foetuses at different stages of gestation. Virus was isolated from a black wildebeest calf. Morphological features and antigenic characteristics suggested it to be a gammaherpesvirus closely related to AlHV-1. All serum samples tested positive with a competitive inhibition enzyme-linked immunosorbent assay (CI-ELISA) for group-specific malignant catarrhal fever virus antibody. A SYBR Green real-time PCR assay was developed for the detection of gammaherpesviral DNA. Only 15.8 % of the animals tested positive with the real-time PCR assay whereas 90 % of the foetuses tested positive. This finding suggests that, unlike OvHV-2 infection in lambs in which the infection takes place after weaning, the virus in black wildebeest is mainly transmitted in utero or soon after birth. The results suggest that black wildebeest are latent carriers of a gammaherpesvirus similar or closely related to AlHV-1 present in blue wildebeest and that it is likely that all black wildebeest are persistently infected.

Ibex-associated malignant catarrhal fever in a bongo antelope (Tragelaphus euryceros).

A 4-yr-old male bongo antelope (Tragelaphus euryceros) died after an acute clinical course involving a febrile illness, anorexia, lethargy, minor oculonasal discharge, and diarrhea. Histologic lesions were compatible with malignant catarrhal fever (MCF). Polymerase chain reaction (PCR) revealed an amplified region of a herpesviral DNA polymerase gene sequence nearly identical to that of a MCF virus previously identified in Nubian ibex (Capra nubiana). The bongo had been housed across from an exhibit containing Nubian ibex that tested positive for MCF viral antibodies by competitive inhibition enzyme-linked immunosorbent assay. Further testing of the zoo's ibex via PCR also revealed viral DNA sequences nearly identical to those found in the bongo's tissues.

[Large outbreak of malignant catarrhal fever in cattle]. / Grote uitbraak van boosaardige catarraal koorts bij rundvee.

The prevalence of clinical malignant catarrhal fever (MCF) is low in the Netherlands, and at a farm level the disease is usually restricted to a single animal. This casereport describes an outbreak of MCF that killed 18 animals (39% of the cattle on the farm). The probable source of infection were 10 hand-reared lambs that were on the farm for a few months.

Genetic characterization of ovine herpesvirus 2 strains involved in water buffaloes malignant catarrhal fever outbreaks in Southern Italy.

Ovine herpesvirus 2 (OvHV-2) was responsible for two outbreaks of malignant catarrhal fever (MCF) on two water buffalo farms in Southern Italy. In this study, the presence of this virus in the nasal swabs from sick animals as well as in the organs of dead buffaloes was ascertained by a Real-time PCR assay. Positive samples also underwent a relative quantitative analysis of the viral DNA in them. All the dead animals had the highest relative viral quantities, while buffaloes recovering from the virus had intermediate quantities, and asymptomatic OvHV-2-positive sheep had the lowest relative quantities (as compared with the calibrator). The strains involved in the MCF outbreaks underwent genetic characterization by sequencing segments of their ORF50, ORF75 and Ov9.5 genes. The results showed that the outbreaks were caused by two specific genetic variants of OvHV-2, and that these variants exhibit nucleotide differences at the loci analysed. Sheep living in the surrounding farms, as well as sheep kept with buffaloes, were also investigated as possible transmitters of the virus. In this regard, local strategies for the control of MCF should consider separating reservoir species from susceptible animals.

Experimental aerosol infection of cattle (Bos taurus) with ovine herpesvirus 2 using nasal secretions from infected sheep.

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.

A devastating outbreak of malignant catarrhal fever in a bison feedlot.

In early 2003, an outbreak of malignant catarrhal fever (MCF) occurred in a bison feedlot in southern Idaho. The outbreak resulted in a 51.2% (n = 825) mortality rate among bison, which had been exposed to sheep for 19 days. Diagnosis was made by detection of ovine herpesvirus 2 (sheep-associated MCF virus) DNA in tissues or peripheral blood by polymerase chain reaction (PCR), and by histological examination of tissue lesions. Peak losses occurred between 41 and 55 days postmean exposure time (PME), and reached a maximum of 41 head per day. No known cases of MCF were observed among the 177 head of bison that arrived in the lot 3 1/2 weeks after the departure of the sheep. Of the several thousand head of beef cattle in the lot during the outbreak, only a single case of MCF was identified. This outbreak illustrates the devastating impact the MCF virus can have on bison under certain exposure conditions, the high threat posed by adolescent lambs to susceptible species, the significantly greater susceptibility of bison than beef cattle to MCF, and the lack of horizontal transmission from clinically affected bison to herdmates.

Molecular epidemiology of ovine herpesvirus type 2 infection in Kashmir, India.

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.

An outbreak of sheep-associated malignant catarrhal fever in bison (Bison bison) after exposure to sheep at a public auction sale.

An outbreak of malignant catarrhal fever (MCF) among bison sold at an auction market was studied for an 18-month period. Forty-five of 163 bison submitted for sale from 8 different bison farms died on 7 other destination farms. The outbreak began on day 50 after the sale, peaked between days 60 and 70, and ended on day 220. Twenty-one dead bison were confirmed to be MCF cases by clinical histories, pathology, and detection of ovine herpesvirus-2 DNA in their tissues with polymerase chain reaction assays. Twenty-four dead bison were classified as suspect MCF cases from clinical histories. No cases of MCF were observed among bison remaining on originating farms or resident bison mixed with sale bison on destination farms. There were no sheep reported within 3 km of originating or destination farms, limiting bison exposure to sheep to the auction facility, where sheep were present for less than 1 day. The outbreak provides an illustration of the temporal distribution of MCF mortality expected in bison and an estimate of the time from exposure until death from MCF after a single short exposure to sheep. The study provides evidence that bison with MCF do not transmit MCF to other bison.

[Virus in sheep's skin]. / Virus im Schafspelz.

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.

Malignant catarrhal fever in a Vietnamese pot-bellied pig. A potential threat to pigs in mixed-species exhibits?

Malignant catarrhal fever (MCF) represents a sporadic and often fatal disease in various ungulate species including rarely swine. A close contact between susceptible and reservoir species of ovine herpesvirus-2 (OvHV-2) is a requirement for virus transmission. As in ruminants, a rapid course of disease with lymphohistiocytic meningoencephalitis and necrotizing vasculitis in multiple organs is frequently seen in porcine MCF. This report describes a case of MCF in a Vietnamese pot-bellied pig, which was kept in a zoological exhibit with direct contact to various ruminants. It represents the first description of porcine MCF with proven natural OvHV-2 infection in Germany. OvHV-2 should be considered as cause of fatalities among swine especially in mixed-species exhibits as present in many zoological gardens. Also farm pigs kept in free ranging husbandry systems with potential contact to sheep and other ruminant species may be at risk.

Transplacental Transmission of Ovine Herpesvirus 2 in Cattle with Sheep-associated Malignant Catarrhal Fever.

Sheep-associated malignant catarrhal fever (SA-MCF) is an important infectious disease of ruminants worldwide that is caused by ovine herpesvirus 2 (OvHV-2). OvHV-2 is transmitted predominantly by contact between infected and susceptible hosts, while the documentation of vertical transmission is rare. This report presents the pathological and molecular findings associated with transplacental transmission of OvHV-2 in cattle. Two Girolanda cows with corneal oedema, lethargy, mucopurulent nasal discharge and ulcerative stomatitis died spontaneously; one of these was pregnant with a 4-month-old fetus. Significant pathological findings included widespread lymphoplasmacytic necrotizing vasculitis and lymphoplasmacytic accumulations in several organs of both cows and the fetus. A polymerase chain reaction that targeted the tegument protein gene of OvHV-2 amplified viral DNA from the brain of the pregnant cow and her fetus, as well as from the kidney of the pregnant cow. The pathological findings observed in the cow and her fetus, together with the presence of OvHV-2 DNA in tissues of these animals, are suggestive of transplacental transmission of OvHV-2 in SA-MCF in cattle.

Alcelaphine Herpesvirus-1 (Malignant Catarrhal Fever Virus) in Wildebeest Placenta: Genetic Variation of ORF50 and A9.5 Alleles.

Alcelaphine herpesvirus-1 (AlHV-1), a causative agent of malignant catarrhal fever in cattle, was detected in wildebeest (Connochaetes taurinus) placenta tissue for the first time. Although viral load was low, the finding of viral DNA in over 50% of 94 samples tested lends support to the possibility that placental tissue could play a role in disease transmission and that wildebeest calves are infected in utero. Two viral loci were sequenced to examine variation among virus samples obtained from wildebeest and cattle: the ORF50 gene, encoding the lytic cycle transactivator protein, and the A9.5 gene, encoding a novel polymorphic viral glycoprotein. ORF50 was well conserved with six newly discovered alleles differing at only one or two base positions. In contrast, while only three new A9.5 alleles were discovered, these differed by up to 13% at the nucleotide level and up to 20% at the amino acid level. Structural homology searching performed with the additional A9.5 sequences determined in this study adds power to recent analysis identifying the four-helix bundle cytokine interleukin-4 (IL4) as the major homologue. The majority of MCF virus samples obtained from Tanzanian cattle and wildebeest encoded A9.5 polypeptides identical to the previously characterized A9.5 allele present in the laboratory maintained AlHV-1 C500 strain. This supports the view that AlHV-1 C500 is suitable for the development of a vaccine for wildebeest-associated MCF.

Demonstration of sheep-associated malignant catarrhal fever virions in sheep nasal secretions.

Ovine herpesvirus-2 (OvHV-2) is the causative agent for sheep-associated malignant catarrhal fever, which has never been propagated in vitro. Previous studies from this laboratory demonstrated significantly high levels of OvHV-2 DNA in sheep nasal secretions, suggesting a likely avenue of transmission. In the present study, real-time PCR was used to identify sheep experiencing an episode of intense OvHV-2 DNA shedding in their nasal secretions. A nuclease-resistance assay was used to examine the secretions for the presence of intact cell-free enveloped OvHV-2 virions. The results revealed that all nasal secretion samples from five selected individuals experiencing intensive shedding events contained cell-free OvHV-2 virions. Virions could not be identified in secretion samples from 11 OvHV-2 infected sheep that were not experiencing a shedding event. This is the first unequivocal demonstration of cell-free OvHV-2 virions. These results suggest that OvHV-2 lytic infection occurs in the epithelium of certain tissues in the upper respiratory tract of the natural host.

Experimental transmission of sheep-associated malignant catarrhal fever from sheep to Japanese deer (Cervus nippon) and cattle.

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.