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.

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.

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.

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.

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.

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.

Experimental nebulization of American bison (Bison bison) with low doses of ovine herpesvirus 2 from sheep nasal secretions.

Malignant catarrhal fever (MCF), caused by ovine herpesvirus 2 (OvHV-2), is an important cause of mortality in ranched American bison and domestic cattle in North America. Previous studies showed that bison can be infected by intranasal nebulization with sheep nasal secretions containing OvHV-2 and provided preliminary information on viral doses required for infection and disease progression. The goals of this study were to establish optimal minimal infectious and minimal lethal doses of OvHV-2 by the intranasal route in bison, evaluate the influence of dose on incubation period and other clinical parameters and determine if bison seropositive for antibody against MCF-group viruses are resistant to developing MCF after intranasal challenge. In this study, the minimal infectious dose and minimal lethal dose overlap, suggesting that experimental production of subclinically infected bison is impractical. Dose is inversely related to both incubation period and the period between nebulization and first detection of >1000 OvHV-2 DNA copies/500 ng total DNA in peripheral blood leukocytes. Interestingly, all of the bison seropositive for anti-MCF-group viral antibody prior to inoculation died of MCF after nebulization. We conclude that previous exposure to an MCF-group virus does not necessarily provide resistance to OvHV-2-induced MCF in bison.

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.

Malignant catarrhal fever: a review.

Malignant catarrhal fever (MCF) is a fatal lymphoproliferative disease of cattle and other ungulates caused by the ruminant gamma-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.

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.

[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.

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.

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.