Ocular lesions of bovine malignant catarrhal fever

The ocular lesions of bovine malignant catarrhal fever were characterized in 15 naturally occurring and eight experimentally induced cases of the disease. Consistent findings included: lymphocytic vasculitis of retinal, scleral, posterior ciliary, and uveal vessels; uveitis, especially involving ciliary processes, ciliary body, and iris; and keratitis with corneal edema, neovascularization, and epithelial and endothelial degeneration. Lymphocytic ciliary neuritis and optic meningitis were found less frequently. Ultrastructural examination of the ciliary body and iris from one experimental calf confirmed that most infiltrating mononuclear cells were lymphocytes. The uveitis, vasculitis, and keratitis of malignant catarrhal fever were probably immune-mediated.     

Transmission studies with bovine malignant catarrhal fever

The intravenous administration of whole blood from a pathologically confirmed field case of bovine malignant catarrhal fever (MCF) resulted in the appearance of the disease in three of five experimental calves 18 to 28 days later. Infection was maintained by serial calf transmissions, and produced clinical and pathological changes identical to those of the field disease for a total of 10 passages. The sixth passage involved the simultaneous infection of 10 calves from a single donor animal; six of the 10 recipients developed the typical disease after incubation periods ranging from 20 to 36 days and in each of these MCF was confirmed by pathological examination. In addition, clinical and pathological changes in the four other calves which were slaughtered either seven or 14 days post-infection suggested that they too would have developed typical clinical signs had they been allowed to survive for the necessary length of time. The results of a detailed study of the onset, progress and duration of the clinical signs of experimentally induced MCF are presented and the opportunity has been taken to discuss the available information regarding the transmission of MCF under experimental conditions and in the field.     

Concurrent malignant catarrhal fever and bovine virus diarrhoea virus infection in a dairy herd

An account is given of an outbreak of malignant catarrhal fever which occurred in a 98-cow dairy herd. Ten animals died or were slaughtered and the disease was confirmed by clinical and histological examination. Serological tests for malignant catarrhal fever virus were positive in three of four animals. The diagnosis of malignant catarrhal fever was complicated by the presence of bovine virus diarrhoea virus infection in three of the early cases. The initial cases of malignant catarrhal fever occurred in a group of nine-month-old calves which were housed in an old milking parlour with 19 pedigree Suffolk ewes at lambing time. Later cases occurred in two adult cows and in two heifers. Investigations of the remainder of the herd for evidence of bovine virus diarrhoea virus did not reveal the presence of any persistently infected cattle. Serological examinations for antibody to malignant catarrhal fever and bovine virus diarrhoea virus were carried out on the 19 Suffolk ewes. Six of them had neutralising antibody titres to malignant catarrhal fever virus and three were positive in the indirect immunofluorescence test. The possible roles of bovine virus     

Epidemiology, pathology, immunology and diagnosis of bovine farcy: a review

Bovine farcy (which is caused by Mycobacterium farcinogenes and Mycobacterium senegalense) is a chronic suppurative granulomatous inflammation of the skin and lymphatics of cattle and is seen mostly in sub-Saharan Africa. It is not yet certain whether Nocardia farcinica causes cutaneous nocardiosis (farcy) in animals that mimics bovine farcy. Epidemiological data have steadily reported finding bovine farcy in adult cattle of the transhumance pastoralist tribes of the Sahel and the Sudanian savannah zones. M. farcinogenes and or M. senegalense do not affect other domestic or non-domestic animals; it is not known whether these bacteria are zoonotic. The disease--once widespread in many regions--has disappeared from some countries historically known to have it. Reports of bovine farcy prevalence seem to be linked to the existence of survey initiatives by governments and diagnostic capabilities in each country. Farcy causes economic loss due to damaged hides and also is a public-health burden (because the lymphadenitis due to farcy resembles the lesions of bovine tuberculosis in carcasses and the meat is considered inappropriate for human consumption). The current literature is deficient in establishing definitely the prevalence, transmission patterns, and risk factors of bovine farcy. Ixodid ticks transmit other skin diseases (such as dermatophilosis) and might play a role in bovine farcy (given the similarity in the bio-physiology and geographic distribution of the disease). In addition, the tick-resistance of cattle breeds such as the N'Dama, Fulani or the Nilotic might explain their resistance to bovine farcy. Apart from the judicious use of conventional smear-and-culture methods, few diagnostic tests have been developed; the molecular and serological tests have not been evaluated for reproducibility and accuracy. This review points out aspects of bovine farcy that need further research and updates available data on the prevalence, distribution, risk factors, economic and public health implications, diagnosis, and control.     

Lytic function of bovine lymphokine-activated killer cells from a normal and a malignant catarrhal fever virus-infected animal

Lymphokine-supplemented long-term cultured bovine lymph node lymphocytes were characterized functionally and phenotypically. Lymphocytes from a normal and a malignant catarrhal fever (MCF) virus-infected animal were maintained without the addition of antigen or feeder cells. Lymphocyte cell lines obtained from both animals: (i) killed allogeneic fibroblasts and allogeneic and xenogeneic cultured tumor cell lines as measured in a 4-h 51Cr release assay, (ii) expressed the same T cell subset marker based on flow cytometry using monoclonal antibodies, and (iii) produced a lytic factor upon stimulation. In contrast, only cells from the MCF virus-infected animal could be maintained for more than 5 months supplemented with 2% Con A-generated lymphokine-containing supernatant. These results suggest that herpesvirus infection enhanced the proliferative capabilities of the cultured lymphocytes from the infected animal. Considering the proliferative and cytotoxic activity together with the T cell phenotype, these data indicated that effector cells are lymphokine-activated killer cells.     

Malignant catarrhal fever: a review

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.     

The malignant catarrhal fever complex

Malignant catarrhal fever (MCF) is defined as a clinicopathological syndrome caused by related herpesviruses and acquired from persistently infected wildebeest and sheep. There is convincing epidemiologic and virologic evidence that Alcelaphine herpesvirus 1 (AHV1) causes the wildebeest-derived disease (WD-MCF). Present knowledge suggests that a herpesvirus related to AHV1 may be associated with some cases of the non-wildebeest-associated disease (NWA-MCF). However, this virus possibly represents a passenger virus not related with the ultimate cause of the disease. Moreover, evidence for the role played by sheep as the reservoir for the agent of NWA-MCF is not convincing and awaits confirmation.     

The location of primary replication of the herpesvirus of bovine malignant catarrhal fever in rabbits

The herpesvirus of malignant catarrhal fever (MCFV) was isolated from the spleen of $\text{2}\text{3}$ rabbits 4 days after the intravenous inoculation of infectious lymph node suspension, while no virus could be isolated at 2 and 6 days post inoculation (p.i.). Indirect immunofluorescence identified the antigen-positive cells at 4 days p.i. as medium sized lymphocytes lying in the venous sinuses of the spleen, lower numbers of fluorescing cells being seen in the paracortical areas of lymph nodes and in the thymus. Scanty fluorescence, without isolation of virus, was evident in the spleen at 6 days p.i. but by day 8 p.i. virus could be isolated irregularly from spleen and lymph nodes and at 12 days p.i. was found in all lymphoid tissues in those rabbits with lymphadenitis and pyrexia. The primary replication in the spleen at 4 days is compared with other herpes induced lymphoproliferative disorders.     

Epidemiology, pathogenesis, treatment and prevention of bovine acute Escherichia coli mastitis, a literature review

Comparisons of the rate of incidence of clinical mastitis caused by E. coli during the last 40 years demonstrate the increasing significance of this disease for modern milk production. Because of the acute nature of this disease it was not possible until now to establish by documentary evidence a spontaneous case from the beginning on--and thereby to give certain evidence to the pathogenesis. Nevertheless a multitude of reports about experimentally caused mastitis or observations of solitary aspects of this disease exists, which allow us to assume that pathogenesis of coliform mastitis as an environmental mastitis and contagious mastitis are basically distinguishable. The manyfold factors which provoke the formation of coliform infections pave the way for methods to reduce the rate of coliform mastitis--incidence by the preventive measures and show how to optimize the results of therapy by beginning earlier and including the whole organism into the concept of therapy.     

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.     

Production of malignant catarrhal fever virus-free sheep

The study was designed to better define the variables affecting the success of the establishment of ovine herpesvirus 2 (OHV-2)-free sheep flocks. A total of 38 lambs born to OHV-2-positive ewes was selected and divided into four groups. Three groups of 10 lambs each were separated from the positive ewes at 2, 2.5 and 3 months of age, respectively, and maintained in isolation facilities. One group of eight remained in the positive flock as controls. Peripheral blood samples from each lamb were examined regularly by PCR for OHV-2 DNA. All lambs (100%) that were weaned and maintained in isolation from the ages of 2, 2.5 and 3 months remained negative until the termination of the experiment at 1 year of age. One lamb was discovered to be PCR-positive on the day of isolation at 2.5 months of age, and was promptly removed from the isolation group. In contrast, all lambs (100%) that remained with the flock became PCR-positive by 6 months of age. The data confirmed that, with rare exceptions, separation of lambs from OHV-2 infected animals at around 2 months of age reliably yields OHV-2-free sheep. Appropriate PCR monitoring will enable the rare exceptions to be removed from the group, and is recommended as a safety measure.     

Immunological relationships between malignant catarrhal fever virus (alcelaphine herpesvirus 1) and bovine cytomegalovirus (bovine herpesvirus 3)

Strains of malignant catarrhal fever virus (alcelaphine herpesvirus 1 (AHV-1)) and bovine cytomegalovirus (bovine herpesvirus 3 (BHV-3)) were compared for serological relatedness by cross-titration in an indirect immunofluorescent (IIF) antibody assay. There was definite cross-reactivity between these 2 viruses, with heterologous sera staining intracellular and membrane antigens of infected cells. Heterologous antibody titres were approximately 50-fold lower than homologous titres and could be removed by absorption with either homologous or heterologous virus-infected cells, but not with uninfected cells. Regression analyses of IIF antibody titres to AHV-1 and BHV-3 virus in 3 groups of wild ungulate sera also indicated a serological relationship between these herpesviruses. In a cross-immunity trial, 2 of 3 cattle immunized with a BHV-3 virus and 2 of 3 cattle immunized with avirulent AHV-1 resisted challenge with virulent AHV-1-infected blood which killed 3 unimmunized controls. These results are discussed particularly with respect to the involvement of BHV-3 in malignant catarrhal fever.