Malignant catarrhal fever. I. Response of American cattle to malignant catarrhal virus isolated in Kenya.

Fifty-three American cattle were inoculated with malignant catarrhal fever virus isolated from a wildebeest in Kenya. Three animals showed the mild form of the disease and recovered, and 47 showed the severe form of the disease. The other three did not react. Of the 47 cattle, 28 died, 16 were killed for the collection of specimens and three recovered. The incubation period for the 47 cattle ranged from 16 to 29 days and the course of the fatal disease for 28 cattle averaged three to 23 days. Virus titration of specimens from nine infected steers yielded a mean titer of 10(4)/TCID50 per gm for lymph nodes, 10(3) TCID50 per mL for buffy coats and 10(2.3) TCID50 per gm for spleens. Smaller amounts of virus were found in the liver, kidneys, adrenals and thyroids. Malignant catarrhal fever virus was also found in nasal secretions and saliva of viremic cattle. Viral infectivity was shown in bovine buffy coat cells stored at 4 degrees C for two days but was immediately destroyed upon freezing even when glycerine or dimethylsulfoxide was added. Viral particles were not found in infected animal tissues by electron microscopy. The disease was successfully transmitted in steers by intratracheal intubation and by aerosol inhalation but not by contact.     

Antibody response in cattle and rabbits to early antigens of malignant catarrhal fever virus in cultured cells.

Cytosine arabinoside (Ara-C) inhibited the production of late antigens and of infectious virus in monolayers of bovine kidney cells infected with the high-passage, WC-11 strain of malignant catarrhal fever virus. Early antigens were not affected. Using hyperimmune and acute-phase sera from cattle and rabbits in indirect immunofluorescence tests, it was shown that Ara-C treated cultures contained two early antigens; one was diffuse and distributed throughout the cells, the other was particulate and intranuclear. Antibody to early antigens developed later and attained lower titres in infected animals, especially rabbits; only hyperimmune sera reacted with the diffuse early antigen.     

Infectivity of cell-free malignant catarrhal fever virus in rabbits and cattle

Malignant catarrhal fever was induced in cattle and rabbits inoculated intranasally with cell-free wildebeest-calf nasal and ocular secretions. This method of reproducing the disease is similar to that occurring in nature and should prove useful as a means of challenging experimentally induced immunity.     

Large outbreak of malignant catarrhal fever in cattle

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.     

Immunoblotting analysis of the reaction of wildebeest, sheep and cattle sera with the structural antigens of alcelaphine herpesvirus-1 (malignant catarrhal fever virus)

Malignant catarrhal fever (MCF) is a disease of cattle and some other ruminants caused by alcelaphine herpesvirus-1 (AHV-1), a virus of wildebeest. The disease also occurs in the absence of wildebeest and is then thought to be caused by a viral agent harboured by the sheep. The structural proteins of AHV-1 have been used as antigens for the immunoblotting analysis of sera from wildebeest, sheep and cattle infected by either AHV-1 or the "sheep-associated" form of the disease. Wildebeest sera showed a uniform response reacting strongly with six polypeptides. Sheep sera also gave positive results but individual sera reacted with varying subsets of the antigens recognized by wildebeest. These results support the earlier suggestion that sheep harbour a herpesvirus related to AHV-1. A bovine serum from a case of MCF caused by AHV-1 also reacted only with a subset of the six wildebeest-reactive polypeptides. Sera from cattle affected with the "sheep-associated" form of the disease gave reactions in only two of the eight cases tested; both positive sera reacted to a few polypeptides only.     

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.     

Antibodies in carrier wildebeest to the lymphoproliferative herpesvirus of malignant catarrhal fever

Six types of antibody to malignant catarrhal fever virus (MCFV) were measured in 132 sera collected from Wildebeest in Kenya Masailand. The titre of all types of antibody declined slowly with increasing age of the wildebeest. A significantly greater proportion of wildebeest calves had higher titres of antibodies to MCFV early antigens, IgM antibodies to MCFV late antigens and complement-fixing antibodies, than did older animals. One seronegative calf, reared in isolation without colostrum, became seropositive 4 1/2 weeks after birth but did not show any clinical signs indicative of MCFV infection. Similarities between MCFV infection of wildebeest calves and other inapparent infections with lymphoproliferative herpesviruses are discussed.     

The development of antibodies in rabbits and cattle infected experimentally with an african strain of malignant catarrhal fever virus

An indirect immunofluorescence (IIF) test for antibody to wildebeest-derived strains of malignant catarrhal fever virus (MCFV) was developed using infected bovine embryonic kidney cells as antigen. This IIF technique and a microtitre method for the assay of virus-neutralizing (VN) antibody were then applied to sequential serum samples from rabbits and calves infected experimentally with a virulent strain of MCFV, which caused lethal disease.Antibody of the IIF type appeared in both species about 6–7 days prior to the onset of pyrexia and increased continuously until death. Neutralizing antibody was detected shortly before the end of the incubation period in the majority of rabbits but was not produced in calves which were killed up to 3 days after reaction. The presence of either antibody did not affect the fatal outcome in rabbits.     

Antibodies to ovine herpesvirus 2 glycoproteins decrease virus infectivity and prevent malignant catarrhal fever in rabbits

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.     

Outbreak of wildebeest-associated malignant catarrhal fever in Ankole cattle

During an outbreak of malignant catarrhal fever in a herd of Ankole cattle in a zoological collection, two adult cows and one adult bull from a herd of 15 died or were euthanased between July and November 2004. The clinical, gross postmortem and histological findings were typical of the disease in uk native domestic cattle. The diagnosis was confirmed by serology in two animals, and by pcr in all three; the pcr provided evidence of alcelaphine herpesvirus type 1 infection in all three animals and also of ovine herpesvirus type 2 infection in one.     

Detection of African malignant catarrhal fever virus antigens in cell cultures by immunofluorescence

A fluorescent antibody (FA) test for antigens of African bovine wildebeest-derived malignant catarrhal fever virus was developed. Serum from one of the few survivors of the experimental disease in steers was used to prepare the conjugate. Both a virulent and an attenuated strain of malignant catarrhal fever virus were used to infect bovine thyroid cell cultures. Cells infected with both strains were readily detected by FA staining as early as 24 h post infection, whereas cytopathic effect could be observed by bright-field microscopy only after days 5 or 6 post infection. Controls consisting of normal bovine thyroid cells or infected cells treated with conjugated normal globulins did not show autofluorescence. The reaction was blocked by treatment of infected cells with homologous positive antisera but not by treatment with normal bovine serum or antisera to foot-and-mouth disease, rinderpest, bovine virus diarrhea, Ibaraki, infectious bovine rhinotracheitis, or bovine herpes mammilitis viruses. Treated with African malgnant catarrhal fever virus conjugate did not react.     

Vitamin D status in cattle with malignant catarrhal fever

The aim of the present study was to determine the vitamin D status in cattle with malignant catarrhal fever (MCF). Twelve cattle diagnosed as MCF and 6 healthy cattle (controls) were used in the study. Serum 1,25-dihydroxyvitamin D(3) (1,25-D), 25-hydroxyvitamin D(3) (25-D), calcium, phosphorus and parathyroid hormone (PTH) levels were determined as 96.83 pg/ml, 30.0 ng/ml, 2.19 mmol/l, 1.57 mmol/l and 15.21 pg/ml in MCF group and 42.33 pg/ml, 37.0 ng/ml, 2.43 mmol/l, 1.96 mmol/l and 36.08 pg/ml in controls, respectively. Although serum 1,25-D level in the MCF group was increased (P<0.01), serum calcium (P<0.01) and PTH (P<0.05) levels were decreased compared to the controls. The results suggest that there might be an interaction between vitamin D status and MCF.     

Immunoglobulins,haemolytic complement and serum C3 in cattle infected with malignant catarrhal fever herpesvirus

Serum levels of the third component of complement (C3) were reduced only in the terminal stages in malignant catarrhal fever (MCF) virus-infected steers. Haemolytic complement and immunoglobulin (IgM, IgG₁ and IgG₂) levels were not altered. C3 and immunoglobulin deposits were also not demonstrated in the vascular lesions induced by MCFV. MCF virus infection of cattle is probably not a typical immune complex-mediated disease as previously suggested.     

Outbreak of malignant catarrhal fever in Welsh Black cattle in Carmarthenshire

An outbreak of malignant catarrhal fever (MCF) resulted in the deaths of 12 cattle in a herd of 77 animals during seven weeks in 1999; in addition, one cow developed a milder disease which was confirmed as MCF by PCR for ovine herpesvirus 2 DNA and an immunofluorescent antibody test for antibodies to the virus, but recovered. Further PCR and serological testing revealed the infection in three other animals, none of which developed clinical disease. Hypocuprosis and the possibility of a genetic predisposition were identified as factors which may have contributed to the outbreak.