Transmission of caprine herpesvirus 2 in domestic goats

Caprine herpesvirus 2 (CpHV-2) is a recently recognized gammaherpesvirus that is endemic in domestic goats and has been observed to cause clinical malignant catarrhal fever (MCF) in certain species of deer. In this study, transmission of CpHV-2 in goats was examined. A total of 30 kids born to a CpHV-2 positive goat herd were selected and divided into two groups: group 1 (n=16) remained in the positive herd; group 2 (n=14) was separated from the herd at 1 week of age after obtaining colostrum. Peripheral blood samples from each kid were examined regularly by competitive ELISA for MCF viral antibody and by PCR for CpHV-2 DNA. Fifteen out of 16 goats (94%) that remained with the positive herd seroconverted and became PCR-positive for CpHV-2 by 10 months of age. In contrast, all kids (100%) that were separated from the positive herd at 1 week of age remained negative until termination of the experiment at 1 year of age. Additional transmission experiments revealed that all CpHV-2-free adult goats were susceptible to CpHV-2 or ovine herpesvirus 2 (OvHV-2) infection. The data indicate that the transmission pattern of CpHV-2 in goats is similar to the pattern of OvHV-2 in sheep and that CpHV-2-free goats can be established by early separation of kids from positive herds, which has significant implications for MCF control programs.     

Caprine herpesvirus-2 in association with naturally occurring malignant catarrhal fever in captive sika deer (Cervus nippon).

Three female sika deer from a single captive herd were submitted for postmortem examination over a 139-day period. The first 2 deer submitted were reported to have lost body mass for 20 days to 1 month before euthanasia. One of these deer had diarrhea, the other had a crusting dermatitis on the nasal planum and inner aspects of both pinnae. The third hind did not have any signs of disease before it was found seizuring and was immediately euthanatized. Microscopically, all 3 animals had a lymphocytic vasculitis typical of malignant catarrhal fever (MCF), with the most severe lesions in the brain. All 3 deer were polymerase chain reaction (PCR) positive for caprine herpesvirus 2 (CpHV-2) and were negative for ovine herpesvirus 2 (OHV-2). Two healthy goats that were housed adjacent to the deer were also PCR positive for CpHV-2 and PCR negative for OHV-2. The CpHV-2, PCR amplicons from the hinds, and the 2 healthy goats had an identical single base polymorphism. A male sika deer that was housed with the hinds and a fawn from 1 of the hinds remained asymptomatic and were PCR negative for CpHV-2. This represents the first report of mortality with MCF-like lesions in association with CpHV-2.     

Sheep-associated malignant catarrhal fever in a petting zoo.

In a privately owned petting zoo in Arizona, 17 deer from five different species, white-tailed deer (Odocoileus virginianus), Reeve's muntjac (Muntiacus reevesi), mule deer (Odocoileus hemionus), reindeer (Rangifer tarandus), and axis deer (Axis axis), died of suspected malignant catarrhal fever (MCF) over a period from late 1992 to early 1995. A PCR assay specific for ovine herpesvirus 2, the putative causative agent of sheep-associated MCF, and a competitive-inhibition enzyme-linked immunosorbent assay based on a monoclonal antibody specific to an epitope conserved among all known MCF viral isolates were used to investigate the outbreak. Ovine herpesvirus 2 DNA sequences were detected by PCR from fresh-frozen and/or formalin-fixed, paraffin-embedded tissue samples in seven deer out of eight available animals previously suspected as cases by histopathology. A high seroprevalence to the virus was found among mouflon (Ovis musimon, 80%) and pygmy goats (Capra hircus, 61%), both of which were present on the farm during the outbreak. Sixteen percent of fallow deer (Dama dama) were also seropositive to the virus. After removal of the mouflon and positive pygmy goats, no further MCF cases occurred on the farm, confirming the importance of careful management to avoid mixing clinically susceptible species with carrier species. Until better control measures are available, adherence to this practice is necessary if MCF is to be prevented in intense exposure environments such as zoos and densely populated animal parks.     

Caprine herpesvirus-1-specific IgG subclasses in naturally and experimentally infected goats

Enzyme-linked immunosorbent assays (ELISAs) were developed to detect caprine herpervirus-1 (CpHV-1)-specific IgG1 and IgG2 in sera from 43 naturally infected goats. The analysis of the IgG subclasses showed a dual pattern of distribution in seropositive goats with a major group of animals (36 out of 43) exhibiting significantly higher levels of IgG2 over IgG1 and a minor group (7 out of 43) possessing equal levels of IgG1 and IgG2. Four goats were experimentally infected with a virulent CpHV-1 Ba.1 strain by the intranasal or the intravaginal route and the kinetics of appearance of CpHV-1-specific IgG, IgG1 and IgG2 in the serum were studied. Two weeks following infection, both IgG1 and IgG2 levels increased although convalescent sera (i.e., collected 5–8 weeks post-infection) showed a clear prevalence of the IgG2 subclass. To determine the contribution of the different IgG subclasses to herpesvirus immunity, serum neutralization (SN) assays were performed in both naturally and experimentally infected goats. The kinetics of SN showed that neutralization activity was mainly associated to the IgG1 subclass and this was also confirmed in naturally infected goats. The results are discussed from the standpoint that the profile of the IgG subclasses is instrumental to study immune responses to CpHV-1 and that vaccination strategies may benefit from this information.     

A live attenuated glycoprotein E negative bovine herpesvirus 1 vaccine induces a partial cross-protection against caprine herpesvirus 1 infection in goats

Taking into account the close antigenic relationship between bovine herpesvirus 1 (BoHV-1) and caprine herpesvirus 1 (CpHV-1), a live attenuated glycoprotein E (gE) negative BoHV-1 vaccine was assessed in goats with the aim to protect against CpHV-1 infection. Vaccine safety was evaluated by intranasal inoculation of two groups of goats with either a gE-negative BoHV-1 vaccine or a virulent BoHV-1. The length of viral excretion and the peak viral titre were reduced with the gE-negative vaccine. To assess the efficacy, two goats were inoculated intranasally twice 2 weeks apart with a gE-negative BoHV-1 vaccine. Four weeks later, immunised and control goats were challenged with CpHV-1. A 2 log(10) reduction in the peak viral titre was observed and the challenge virus excretion lasted 2 days more in immunised than in control goats. These data indicate the safety and the partial efficacy of a live attenuated gE-negative BoHV-1 vaccine intranasally administrated in goats.     

A preliminary study on the pathogenicity of a strain of caprine herpesvirus-1

The strain BA-1 of caprine herpesvirus-1 (CpHV-1), isolated from latently infected goats, was inoculated intranasally into three five-year-old goats. The animals developed fever and leukopenia. The signs began on post-inoculation day (PID) 4 and lasted 7 days. In one goat herpes-like lesions appeared on the vulvar area on PID 7. Virus was consistently recovered from the nasal and the vaginal swabbings obtained from the three goats. Virus was never recovered from the ocular and rectal swabbings nor from any buffy coat samples. However, the buffy coats were positive for viral DNA detected by polymerase chain reaction (PCR). All isolates from the experimental goats were identical in their restriction patterns to the original BA-1 and were similar to the reference E/CH strains of CpHV-1.     

Serologic and reproductive findings after a herpesvirus-1 abortion storm in goats

CASE DESCRIPTION: An abortion storm occurred in a goat herd, resulting in 75 aborted kids and 1 neonatal death from December 2004 to February 2005. CLINICAL FINDINGS: Aborted fetuses ranged from being premature to past term. Laboratory findings in 4 of 5 aborted fetuses were consistent with herpesvirus abortion. A virus that yielded positive results with a fluorescent antibody test for bovine herpesvirus-1 was isolated and identified as caprine herpesvirus-1 (CpHV-1) via DNA sequence analysis. TREATMENT AND OUTCOME: Many does that aborted were rebred for kidding in late summer. Most of the young wethers born in 2005 were sold; however, all of the young does were kept for breeding in fall. In November 2005, all 241 goats in the herd were tested for antibodies against CpHV-1 to identify goats that had seroconverted during the outbreak. No complications attributable to CpHV-1 were identified during kidding in 2006. CLINICAL RELEVANCE: On the basis of serologic findings, infection with CpHV-1 was not associated with reduced reproductive success in the subsequent breeding.     

Isolation of caprine herpesvirus type 1 in Spain

Two strains of caprine herpesvirus type 1 (CpHV-1) were isolated after the experimental reactivation of two seropositive goats in Spain. Viral DNA from these isolates was compared with DNA from bovine herpesvirus type 1 and CpHV-1 reference strains by restriction endonuclease analysis. The two Spanish isolates were closely related but could easily be distinguished from each other and from the reference strains.     

Serological evidence of caprine herpesvirus 1 infection in Mediterranean France

Caprine herpesvirus 1 (CpHV-1) is responsible of a systemic disease in kids and genital diseases inducing abortions in adult goats. In Europe, CpHV-1 is widespread in Mediterranean countries such as Greece, Italy and Spain. As France is geographically close to these countries, a survey was conducted to investigate the presence of CpHV-1 in goats in a Mediterranean department (Corse-du-Sud) and in continental departments (Dordogne and Vendée) of this country. Taking into account the close antigenic and genetic relationships between bovine herpesvirus 1 (BoHV-1) and CpHV-1, the serological detection was performed by using BoHV-1 glycoproteins B (gB) and E (gE) blocking ELISAs. The analysis of 2548 serum samples in a BoHV-1 gB blocking ELISA revealed that a ruminant alphaherpesvirus infection related to BoHV-1 was widespread in Corse-du-Sud whereas no positive animals was detected in Dordogne and Vendée. Furthermore, the specificity and the sensitivity of the BoHV-1 gB blocking ELISA to detect a BoHV-1 related infection in goats were evaluated. A subsequent analysis by a BoHV-1 gE blocking ELISA demonstrated that 22.6% of gB-positive serum samples were also gE-positive. Cross-seroneutralisation assays afforded the unambiguous identification of antibodies against CpHV-1 in gB-positive goats. The likely presence of CpHV-1 in Corse-du-Sud supported by a high seroprevalence (61.9%) in all investigated flocks extends the number of countries infected with CpHV-1. Moreover, the difference observed between Corse-du-Sud and Dordogne and Vendée suggests that CpHV-1 is more prevalent in Mediterranean countries or regions than in central and northern Europe.     

A serologic survey of viral infections in captive ungulates in Turkish zoos

Zoos and zoologic gardens make optimal environments for interspecies transmission of viral infections. There are seven zoos and several small zoologic collections in Turkey. This study aimed to determine the current status of viral infections in captive ungulates living in these environments. Blood samples were taken from 163 captive animals from two zoos. There were 39 Cameroon sheep (Ovis ammon f aries), 11 Barbary sheep (Ammotragus lervia), 57 pygmy goats (Capra hircus), 9 Angora goats (Capra hircus), 21 mountain goats (Capra aegagrus-aegagrus), 7 llamas (Lama glama), 8 Persian goitred gazelle (Gazella subgutturosa subgutturosa), 7 Caspian red deer (Cervus elaphus maral), 2 fallow deer (Dama dama), and 2 camels (Camelus dromedarius). Antibodies against bovine viral diarrhea virus (BVDV), bovine herpesvirus-1 (BHV-1), bovine adenoviruses (BAV-1 and -3), parainfluenzavirus 3 (PI-3), and bluetongue viruses (BTV-4 and -9) were investigated using the virus neutralization test, and malignant catarrhal fever (MCF) antibodies were screened by ELISA. All animals were negative for BVDV and BHV-1 antibodies. Seroprevalence of BAV-1, BAV-3, PI-3, BRSV, BT-4, BT-9, and MCF were detected as follows: 46.6%, 60.1%, 0.6%, 7.3%, 1.8%, 1.2%, and 51.6%, respectively. Seroprevalence of BAVs and MCF were more common than all other viruses (P < 0.0001). Ten sheep (37.0%), 48 goats (84.2), and 1 Ilama (14.2%) were the only species positive for MCF antibodies. Prevalence of BRSV and MCF antibodies were found to be significantly higher in goats than in sheep. BTV antibodies were detected both in Cameroon sheep and mountain goats and suggest that zoo animals are at risk for BTV in endemic regions.     

Development of a management program for a mixed species wildlife park following an occurrence of malignant catarrhal fever

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.     

Serological evidence of lack of contact with caprine herpesvirus type 1 and bluetongue virus in goat population in Poland

Investigation into herd-level seroprevalence of caprine herpesvirus type 1 (CpHV-1) and bluetongue virus (BTV) was conducted in 2007 in Poland. It involved the entire population of goats covered by a milk recording program in 2007, which included 49 goat herds. The number of goats examined in each herd was determined statistically in order to detect the presence of at least one seropositive animal in a herd with a 95% probability and simple random method of sampling was applied. No antibodies to CpHV-1 or BTV were detected. Further calculations were carried out to determine the herd-level true seroprevalence, taking into account sensitivity and specificity of the test as well as several other factors. It can be concluded that till the middle of 2007 population of Polish goats covered by the milk recording program remained negative with respect to CpHV-1 and BTV.     

Giardia duodenalis and Cryptosporidium parvum infections in adult goats and their implications for neonatal kids

During the kidding season between January and April 2003, 10 farms were selected and divided into two groups of five. The farms in group A had had serious diarrhoeal illness and losses in neonatal kids the previous year, and there were Cryptosporidium parvum infections in kids associated with diarrhoea during the survey. On the farms in group B, there was no history of diarrhoeal disease the previous year and neither C parvum oocysts nor diarrhoea were detected in neonatal kids during the survey. Faecal samples were collected once from 10 adult goats aged between one and seven years on each farm. To assess more accurately the pattern of output of oocysts of C parvum and cysts of Giardia duodenalis by periparturient adult goats, one farm was selected from each group, faecal samples were collected weekly before and after kidding from 12 goats on the farm in group A and from 10 goats on the farm in group B. There was no significant difference in the prevalence of G duodenalis cysts between the group A farms (14 per cent) and the group B farms (12 per cent), and the numbers of cysts excreted ranged from 143 to 400 cysts per gram of faeces (cpg) on the group A farms and 72 to 334 cpg on the group B farms. There was a significant difference (P=0.03) in the prevalence of C parvum oocysts at the group level between the group A farms (20 per cent) and the group B farms (6 per cent). All the adult goats excreted cysts and oocysts at some date around the kidding period; the number of animals excreting cysts of G duodenalis or oocysts of C parvum increased when they gave birth, and seven to 10 times more cysts and oocysts were shed in the three weeks around kidding than in the period more than three weeks from kidding (P<0.001).     

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.     

Diagnosis of malignant catarrhal fever by PCR using formalin-fixed, paraffin-embedded tissues.

A previously described polymerase chain reaction (PCR) assay (amplification of a 238-bp fragment of ovine herpesvirus 2 [OHV-2] genomic DNA) for diagnosis of sheep-associated malignant catarrhal fever (MCF) was adapted for use on formalin-fixed, paraffin-embedded tissues. Variables affecting its use were examined. Archived tissues from cattle, white-tailed deer (Odocoileus virginianus), and bison (Bison bison) diagnosed with MCF by clinical signs or histologic lesions were obtained from 2 veterinary diagnostic laboratories. Tissues from healthy animals and from animals diagnosed with other common bovine viral diseases were examined as controls. A total of 86 blocks from 37 suspect MCF cases were examined. Forty-one blocks from healthy animals and animals with unrelated viral diseases were examined as controls. The assay was specific for sheep-associated MCF and did not yield false-positive signals from healthy animals or from cases of infectious bovine rhinotracheitis, bovine virus diarrhea, mucosal disease, or parainfluenza-3 virus infection. A wide variety of tissues were suitable substrates, including spleen, lymph node, intestine, brain, lung, and kidney. Extracted DNA provided a more suitable target than did unextracted tissue lysate. The highest levels of viral DNA were present in lymphoid organs and intestine, but the data indicate that in acute clinical cases, most organs contain sufficient viral DNA to serve as a suitable diagnostic specimen. Fixation of 0.5-cm3 blocks of tissue in 10% neutral buffered formalin was deleterious to the target DNA, and PCR signals progressively diminished after fixation for >45 days. Detection of genomic DNA of OHV-2 by PCR was successful for archived tissues that were 15 years old.     

Characteristics of the herpesvirus of malignant catarrhal fever isolated from captive wildebeest calves

A herpesvirus was isolated from buffy coat cells from a newborn wildebeest (Connochaetes gnou) and from tissues of a 12-day-old wildebeest during the 1982 calving season of a captive, inbred herd maintained in a zoologic collection. Both wildebeests were clinically healthy, and there was no herd record that malignant catarrhal fever (MCF) existed. Each viral isolate produced cytopathologic changes in bovine kidney cell cultures (intranuclear inclusions and massive syncytia). The viral-infected cell cultures contained antigens of MCF virus detected by immunofluorescence. The morphology of each viral isolate as determined by electron microscopy was that of a herpesvirus. Suspensions of 4 to 5 ml of disrupted cell culture material which contained virus from each wildebeest were inoculated (IV) into white-tailed deer (Odocoileus virginianus). Each deer became clinically ill within 28 days. Both deer had mucoid catarrh and a febrile response (40.5 to 41 C). Each also seroconverted to MCF virus. The histopathologic change in the tissues from the 2 inoculated deer was vasculitis. At 16 to 17 days after the deer were inoculated, a syncytial-forming virus was isolated from each deer from buffy coat cells fused with polyethylene glycol (1000) to bovine fetal kidney cells. The virus was identified as MCF virus by immunofluorescence and production of antibody to MCF virus. The presence of virus in the inbred wildebeest herd established this species as a reservoir or latent carrier of African MCF virus at the zoologic park.     

Antigen-specific IFN-gamma and IL-4 production in caprine herpesvirus infected goats

The analysis of cytokines secreted by antigen-specific lymphocytes is hampered in goats by the paucity of species-specific reagents yet it is crucial to study immune responses to infections. To overcome this limit, two commercial kits designed to measure soluble bovine IL-4 (by ELISA) and frequencies of bovine IFN-gamma secreting cells (by ELISPOT) were tested for cross-reactivity in goats. In addition, an ELISA specific to bovine/ovine IL-4 and employing two monoclonal antibodies, clones CC313 and CC314, was tested as well. Concanavalin A-stimulated caprine peripheral blood mononuclear cells (PBMCs) cultures were studied and they exhibited high levels of soluble IL-4 and high frequencies of IFN-gamma secreting cells. In addition, the two IL-4 ELISAs detected similar amounts of cytokine. To start defining the cytokine response triggered by caprine herpesvirus 1 (CpHV-1) infection, PBMC cultures were setup from goats naturally or experimentally infected with CpHV-1. High frequencies of IFN-gamma producing cells and low, when detectable, levels of soluble IL-4 were observed in CpHV-1-specific PBMC cultures from both groups of infected goats. Thus, the availability of cross-reactive research tools can expand cytokine studies in goats and can implement the research on immunity to other caprine infections.     

Mycobacterium avium subsp. paratuberculosis from free-ranging deer and rabbits surrounding Minnesota dairy herds

The objectives of this study were to estimate the prevalence of Mycobacterium avium subsp. paratuberculosis (MAP) among deer and rabbits surrounding infected and noninfected Minnesota dairy farms using fecal culture, and to describe the frequency that farm management practices were used that could potentially lead to transmission of infection between these species. Fecal samples from cows and the cow environment were collected from 108 Minnesota dairy herds, and fecal pellets from free-ranging white-tailed deer and eastern cottontail rabbits were collected from locations surrounding 114 farms; all samples were tested using bacterial culture. In addition, a questionnaire was administered to 114 herd owners. Sixty-two percent of the dairy herds had at least 1 positive fecal pool or environmental sample. A total of 218 rabbit samples were collected from 90% of the herds, and 309 deer samples were collected from 47% of the herds. On 2 (4%) of the farms sampled, 1 deer fecal sample was MAP positive. Both farms had samples from the cow fecal pool and cow environment that were positive by culture. On 2 (2%) other farms, 1 rabbit fecal sample was positive by culture to MAP, with one of these farms having positive cow fecal pools and cow environmental samples. Pasture was used on 79% of the study farms as a grazing area for cattle, mainly for dry cows (75%) and bred or prebred heifers (87%). Of the 114 farms, 88 (77%) provided access to drylot for their cattle, mainly for milking cows (77/88; 88%) and bred heifers (87%). Of all study farms, 90 (79%) used some solid manure broadcasting on their crop fields. Of all 114 farms, the estimated probability of daily physical contact between cattle manure and deer or rabbits was 20% and 25%, respectively. Possible contact between cattle manure and deer or rabbits was estimated to occur primarily from March through December. The frequency of pasture or drylot use and manure spreading on crop fields may be important risk factors for transmission of MAP among dairy cattle, deer, and rabbits. Although the MAP prevalence among rabbits and deer is low, their role as MAP reservoirs should be considered.     

Parapoxvirus infections in New Zealand farmed red deer (Cervus elaphus)

Outbreaks of infection due to a parapoxvirus were reported on eight New Zealand deer farms. Scabby lesions were seen variably on the muzzle, lips, face, ears and neck of red deer (Cervus elaphus) with morbidity rates reaching 100%. On three farms multifocal lesions were also present on the velvet. Deaths were reported on two properties where the lesions were extensive and secondary bacterial infections had occurred. On one of these farms multifactorial disease was suspected. Poxvirus particles were seen by negative contrast electron microscopy in scab material from all eight properties. Morphologically the deer virus resembled a parapoxvirus, but restriction endonuclease analysis showed its DNA fragment patterns were distinct from those of orf (contagious ecthyma) virus.     

Malignant catarrhal fever: experimental transmission of the 'sheep-associated' form of the disease from cattle and deer to cattle, deer, rabbits and hamsters

Attempts to transmit malignant catarrhal fever (MCF) from 16 bovine cases of the 'sheep-associated' form of the disease are described. On two occasions disease was transmitted to bovine calves but transmission to red deer (Cervus elaphus) was not achieved. In addition, MCF was transmitted from one experimentally affected calf to a rabbit and on another occasion directly to rabbits with material from a field case which failed to transmit to a bovine calf or red deer. Subsequently each of these isolates was readily passaged through rabbits and one was also passaged to Syrian hamsters. Tissue from MCF-affected red deer consistently produced disease on inoculation into rabbits and deer but failed to cause disease in bovine calves. Contact infection between red deer occurred once and roe deer (Capreolus capreolus) were also shown to be susceptible to infection by inoculation. Passage of MCF in rabbits with an isolate from red deer failed to produce evidence of further adaptation even after 125 serial passages. Despite the failure to transmit disease from cattle to deer or from deer to cattle it is considered probable that there is only one sheep-associated agent which causes MCF in both species. The reasons for the anomalies in transmission of this form of the disease are discussed.