Studies on bovine herpesviruses. Part 1. Isolation and characterization of viruses isolated from the genital tract of cattle

Herpesviruses, previously isolated from cattle (Theodoridis, 1978), were further studied and provisionally placed in the bovid herpesvirus 4 (BHV-4) group. Major differences were found between IBR-IPV (BHV-1) and BHV-4 virus strains. In MDBK cells, all BHV-4 strains started growing at the edges of the culture, the process progressing slowly until destruction of the cells was complete by the 10th day. BHV-4 strains failed to induce neutralizing antibodies in cattle, goats and rabbits. Only the addition of mineral oil adjuvant induced neutralizing and complement fixing antibodies in goats. BHV-1 strains, in contrast, produced very potent antisera in all these systems. Cross-neutralization tests indicated the existence of 2 distinct serological groups representing BHV-1 and BHV-4. The BHV-4 strains appear to be interrelated and they could not be grouped. A BHV-1 strain showed fixation of complement with the antisera of 6 BHV-4 strains. Electron micrographs showed an accumulation of nucleocapsids in the cytoplasm and an early release of virus particles due to cell destruction. Variation in incubation temperature had a significant effect on the particle formation. At lower temperatures, the number of enveloped particles in the cytoplasm increased. On the basis of the characteristics uncovered in this study, it is possible that all the BHV-4 strains represent one and the same virus which has undergone certain biological changes, thus illustrating a phenomenon which appears to be a characteristic of the herpesviruses.     

Reaction of goats to infection with infectious bovine rhinotracheitis virus

Intranasal exposure of goats to infectious bovine rhinotracheitis virus resulted in mild respiratory disease and virus reisolation from nasal secretions. No disease was produced in goats exposed to the same virus by the genital or ocular routes. There was serological evidence of contact transmission of infection from infected goats to cattle. Virus recrudescence was not detected in goats treated with dexamethasone two months after virus inoculation.     

Comparison between strains of infectious bovine rhinotracheitis virus (Bovid herpesvirus 1), from respiratory and genital origins,using polyacrylamide gel electrophoresis of structural proteins

The polypeptide composition of three strains of infectious bovine rhinotracheitis virus, isolated from typical respiratory disease (IBR), has been compared with that of three strains isolated from the genital tract of cattle suffering from infectious pustular vulvovaginitis (IPV). All the IBR strains are similar to each other, but different from the IPV strains, which in turn were similar to each other. IBR isolates and IPV isolates differed in three polypeptides.     

Sero-prevalences of selected cattle diseases in the Kafue flats of Zambia

Sera from five traditionally managed herds grazing in the Kafue flats were tested for antibodies to bovine viral diarrhoea-mucosal disease (BVD-MD), parainfluenza 3 (PI3), infectious bovine rhinotracheitis-infectious pustular vulvovaginitis (IBR-IPV), bovine adenovirus 3 (BAV3) and Bluetongue (BT). The sero-prevalences of the first four diseases were respectively 76.2, 94.4, 42.1 and 87.4%. Five samples (2.3%) gave doubtful reactions for BT. Prevalences of 28.5% for brucellosis, 14% for Rift Valley fever (RFV), 0.9% for Q fever and 11.2% for chlamydiosis were also recorded. Significantly higher values for BVD-MD (p<0.005), IBR-IPV (p<0.01) and brucellosis (p<0.05) were found in animals over 1 year of age. No differences were recorded between herds or between male and female animals.The high concentration of wild and domestic ruminants grazing together in the flood plains during the dry season may be a major determinant of the high values observed. Traditional farmers, slaughterhouse workers and other people involved in livestock production are particularly at risk of contracting brucellosis and RVF because of the high prevalences in cattle and local habits favourable to their transmission.     

The IBR-IPV virus-serum neutralization test. Sensitivity and significance of the tissue culture tube test

A modification of the IBR-IPV virus-serum neutralization test (tissue culture tube test) was used in examinations of three groups of cattle: animals at AI centres; selected herds from infected districts; and pregnant cows and heifers from all over the country. In, respectively, 141 samples out of 1335, 215 out of 344, and 46 out of 7928, a virus-neutralizing effect was demonstrated. Within the three groups of samples, respectively, 2.8 %, 29.4 %, and 28.3 % of samples positive by the modified test were negative by the conventional test, even with undiluted serum. The findings gave strong evidence that all positive reactions were results of a preceding infection. All animals with a history of infection responded serologically when examined by the modified test, but still the distribution of the titers recorded in herd examinations indicates the desirability of a further improvement in the sensitivity of the test.     

The biology of bovine herpesvirus-4 infection of cattle

The biology of bovine herpesvirus-4 (BHV-4) infection of cattle is reviewed. The infection is distributed worldwide. Most of isolated viruses are non-pathogenic in cattle; some of them are able to produce a genital disease. Twenty-nine structural polypeptides were described; ten of them are glycosylated. Two major glycoproteins were characterized by monoclonal antibodies. Restriction maps of BHV-4 DNA are available for the enzymes EcoRI, BamHi and HindIII. The strain variations studied by restriction analysis are very weak. The virus is able to persist in a latent state after primary infection. The identified sites of latency are nervous ganglia and mononuclear blood cells. The immune response of cattle after BHV-4 infection is characterized by low or undetectable levels of neutralizing antibodies. Four envelope proteins are recognized by convalescent sera and are the main antigenic components. Skin test remains negative in immunized cattle. Bovine herpesvirus-4 is not strictly species-specific: infection was proved in American bison (Bison bison), African buffalo (Syncerus caffer), sheep and probably cat, because feline herpesvirus-2 is in fact a BHV-4 strain. Finally BHV-4 shares antigenic and genomic relationships with alcelaphine herpesvirus-1, the causal agent of the African form of malignant catarrhal fever.     

The Incidence and Significance of Bovine Herpesvirus (infectious bovine rhinotracheitis) Antibodies in the Sera of Aborting Cattle

The results of bovine herpesvirus (IBR-IPV) neutralization tests conducted on the sera of 463 animals with a prior history of undiagnosed abortion and 331 control animals with no history of abortion are reported. One hundred and thirty-one (28.3 per cent) of the aborting and 105 (31.7 per cent) of the control animals, were found to harbour antibody to this virus. No significant seasonal or gestational incidence could be determined but some variation in the annual incidence was apparent. On the basis of these results it appears unlikely that this virus is responsible for a significant proportion of the undiagnosed cases of bovine abortion in Quebec and Ontario, where the animals tested were located. The problems involved in substantiating a diagnosis of abortion due to bovine herpesvirus are briefly discussed.     

Viral agents as the cause of reproductive disorders in cattle and available vaccines]

After a review on the viral agents playing a role in diseases of cattle those related to the occurrence in the genital tract are described. They may be causing abortion or local reactions leading to a reduced fertility and/or be of importance for the embryo transfer. Bovine herpesvirus type 1 (BHV1) and the bovine virus diarrhoea virus (BVDV) are the agents most widely distributed in Europe. Both are of economic importance, described in detail and vaccines available discussed.     

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.     

The pathogenesis and immunology of bluetongue virus infection of ruminants

Bluetongue (BLU) virus is transmitted from infected to susceptible ruminants by hematophagous vector midges (Culicoides species). Cattle are important reservoir hosts of the virus because infection typically is asymptomatic and characterized by prolonged cell associated viremia, and because at least some species of insect vector preferentially feed on cattle. Interaction of BLU virus with the cell membrane of erythrocytes in infected cattle likely facilitates both prolonged viremia as well as infection of the insect vector. BLU disease is most common in sheep and some wildlife species. A variety of host, agent and environmental factors clearly can influence expression of disease in these species. The pathogenesis of BLU virus infection of cattle and sheep is remarkably similar, thus the basis for expression of disease in sheep but not cattle remains to be firmly established. Some difference in susceptibility of endothelial cells to infection in the two species is one potential explanation.

Ruminants develop a variety of antiviral responses after BLU virus infection. Antibodies to outer capsid protein VP2 are responsible for virus neutralization, and confer resistance to reinfection with the homologous serotype of BLU virus. Antibodies to epitopes on proteins which are common to all viruses of the BLU serogroup form the basis of current diagnostic serologic tests. Cell mediated responses have been incompletely characterized, in part because BLU virus replicates within dividing lymphocytes and virus-mediated cytolysis inhibits in vitro blastogenesis. Immunological competence of ruminants to BLU virus arises prior to midgestation, and suggestions that persistent immune tolerant BLU virus infection occurs after in utero exposure of cattle have not been substantiated and are not consistent with recent findings.     

Antibody to alcelaphine herpesvirus-1 (AHV-1) in hamsters experimentally infected with AHV-1 and the 'sheep-associated' agent of malignant catarrhal fever

Malignant catarrhal fever was induced in four groups of hamsters by the inoculation of cells infected with either the C/500 isolate of alcelaphine herpes-virus-1 (AHV-1) or the sheep-associated agent derived from cattle, red deer or Père David's deer. Using an indirect immunofluorescence assay, antibody to AHV-1 was detected in sera of clinically affected animals of all four groups. The reaction of sera from hamsters affected with malignant catarrhal fever induced by AHV-1 caused diffuse cytoplasmic staining while that from sera of hamsters with the sheep-associated form of the disease stained particulate nuclear antigens. Tests employing three other bovid herpesviruses were negative and no reaction was found with sera from normal hamsters. These studies provide convincing evidence that a virus antigenically related to AHV-1 is the cause of sheep-associated malignant catarrhal fever and that the same virus probably causes this form of the disease in both cattle and deer.     

Antibody titers against bovine coronavirus and shedding of the virus via the respiratory tract in feedlot cattle

OBJECTIVE: To describe patterns of seroconversion to bovine coronavirus (BCV) and shedding of BCV from the respiratory tract in feedlot cattle. ANIMALS: 1,074 calves in feedlots in Ohio, Texas, and Nebraska. PROCEDURE: Nasal swab specimens were obtained at time of arrival (day 0) and at various times during the initial 28 days after arrival at feedlots. Specimens were tested for BCV, using an antigen-capture ELISA. Serum samples were obtained at time of arrival and again 28 days after arrival; sera were analyzed for antibodies to BCV, using an antibody-detection ELISA. RESULTS: Samples from 12 groups of cattle entering 7 feedlots during a 3-year period revealed that 78 of 1,074 (7.3%) cattle were shedding BCV (range, 0 to 35.9% within specific groups). At time of arrival, 508 of 814 (62.4%) cattle had low (< 50) or undetectable BCV antibody titers. Seroconversion to BCV during the initial 28 days after arrival was detected in 473 of 814 (58%) cattle tested (range, 20.3 to 84.1 % within specific groups). In cattle shedding BCV from the nasal passages, 49 of 68 (72.1 %) seroconverted, and 472 of 746 (63.3%) cattle that were not shedding the virus seroconverted. CONCLUSIONS AND CLINICAL RELEVANCE: Bovine coronavirus can be detected in populations of feedlot cattle in the form of viral shedding as well as seroconversion to the virus. Although only a few cattle were shedding the virus at the time of arrival at a feedlot, most of the cattle seroconverted to BCV by 28 days after arrival.     

BLUETONGUE: THE DISEASE IN CATTLE

Most researchers in South Africa found that although BT virus could be isolated from apparently healthy cattle and from inoculated cattle the virus did not produce overt clinical disease in cattle. However, when epizootics were reported outside Africa, clinical signs were observed in cattle in Israel, Palestine, Syria, Portugal, and Spain. Most natural BT infections in cattle in the United States do not result in overt clinical signs. However, in certain infected herds, approximately 5% of the cattle show from mild to severe disease. Except for severe cases, spontaneous recovery is usual. The clinical diagnosis of BT in cattle is difficult and requires laboratory assistance. Culicoides variipennis can serve as a vector of BT virus from cattle to cattle, cattle to sheep, sheep to cattle, and sheep to sheep. In utero transmission occurs in cattle and can result in abortion, hydraencephaly, congenital deformity, and birth of viraemic calves which may or may not develop BT antibody. Calves inoculated in utero or those born to infected dams may have a persistent viraemia with or without BT antibody. tone such animal has been held in insect-secure quarters and has continued to harbour virus for 3 years. Bluetongue virus was isolated from the semen of experimentally infected bulls. Calves inoculated with BT virus and also given an immuno-suppressant developed marked clinical disease in 8 to 12 days. Bluetongue virus is very closely associated with the erythrocytes of infected cattle, sheep, and goats. Cattle are considered important and relatively long-term virus reservoirs. In attempts to determine the maximum period of viraemia in cattle it is necessary to inoculate washed erythrocytes, rather than whole blood, and to use susceptible sheep as the assay system rather than embryonated chicken eggs.     

Lymphocyte blastogenesis and neutrophil function in cattle persistently infected with bovine viral diarrhea virus

Neutrophil function and mononuclear cell proliferative responses to mitogens were determined in healthy cattle and in cattle persistently infected with bovine viral diarrhea (BVD) virus. Uptake of [3H]thymidine by resting and mitogen-stimulated peripheral blood mononuclear cells was significantly lower in cattle persistently infected with BVD virus than in healthy cattle. Neutrophils from cattle persistently infected with BVD virus had significantly impaired capability to ingest Staphylococcus aureus, but were normal in respect to random migration under agarose, cytochrome C reduction, iodination, and antibody-dependent cell-mediated cytotoxicity. Impairment of neutrophil function in cattle persistently infected with BVD virus differs from impairment of neutrophil function reported in healthy cattle mounting an immune response to recent BVD virus infection.     

A sentinel herd system for the study of arbovirus infections in Australia and Papua-New Guinea

The establishment, and development between 1969 and 1978, of a system of sentinel cattle in herds located in many areas of Australia and in Papua New Guinea is described. Though the system was established for the study of the epidemiology of a variety of viruses infecting cattle, the study has been limited since 1974 to arboviruses. By means of serology, it was established that bovine ephemeral fever virus was present in Australia in subclinical form between major epidemics but was not detected in Papua-New Guinea. The development of antibody to bovine ephemeral fever virus in individual cattle before they developed clinical signs in epidemics was clearly demonstrated. The sentinel technique was used to demonstrate that subclinical Akabane virus infection in cattle occurred at the time that virus was present in its suspected vector,Culicoides brevitarsis which had been collected nearby. The epidemiology of other Simbu group viruses, D'Aguilar virus, and bluetongue virus, (serotype 20) was also studied. A limited programme of arbovirus isolation in tissue cultures produced 0.8% of isolates from 2090 of the blood clots which accompanied sentinel herd serum samples.The most valuable aspect of the sentinel herd scheme has been the accumulation of a well documented representative set of serum samples for retrospective serology by the use of newly isolated or imported antigens.     

Responses of cattle, sheep and poultry to a recombinant vaccinia virus expressing a swine influenza haemagglutinin

Groups of cattle, sheep and poultry were inoculated with a recombinant vaccinia virus expressing the haemagglutinin of the swine influenza virus A/NJ/11/76. No adverse clinical responses were recorded and none of the animals developed a viraemia when inoculated with the recombinant or wild-type vaccinia virus. Recombinant virus reisolated from lesions in cattle was stable, maintaining its thymidine kinase negative phenotype and ability to express the swine influenza haemagglutinin. Antibodies to the influenza haemagglutinin were detected in cattle, sheep and poultry inoculated with the recombinant virus. While no animals inoculated with wild-type virus developed these antibodies, there was no detectable spread of either recombinant or wild-type virus from the inoculation sites or to in-contact uninoculated animals. The results indicate that recombinant vaccinia viruses can induce immune responses in cattle, sheep and poultry demonstrating their potential as vaccine vectors in a variety of important veterinary species.     

Mass screening of cattle sera against 14 infectious disease agents, using an ELISA system for monitoring health in livestock.

Mass screening ELISA methods were developed for testing cattle serum for antibodies against 14 common livestock diseases simultaneously. The absorbance values were transformed to a %ELISA (spectrophotometric antibody end point) by a computer interfaced with a microplate reader. A histogram indicating a cutoff point and a report for the veterinarian also was generated. The computer program produced a print-out of the antibody profile for each animal tested, the antibody concentration against each disease, and a histogram (antibody profile) showing the prevalence of each disease in the herd. Serum samples were obtained from 1,953 cattle, including 880 dairy cattle from 10 herds and 1,073 beef cattle from 20 herds. These samples were obtained from June 1988 through June 1989. The highest antibody prevalence was against bluetongue virus. Of the 1,953 cattle tested, 1,223 (63%) were seropositive for bluetongue virus, including 502 (57%) of the dairy cattle and 721 (67%) beef cattle. Other antibody prevalences, in descending order, were: rotavirus (44%), Pasteurella spp (25%), Leptospira spp and Haemophilus spp (22%), Mycoplasma spp (18%), parainfluenza virus (17%), Campylobacter spp (16%), Anaplasma marginale (15%), bovine leukosis virus (13%), Brucella spp (8%), Mycobacterium paratuberculosis (8%), bovine viral diarrhea virus (3%), and infectious bovine rhinotracheitis virus (3%). Major differences in antibody prevalence between dairy and beef cattle were that only 4% of the dairy cattle were seropositive for A marginale, compared with 25% of the beef cattle, and conversely, 29% of the dairy cattle were seropositive for bovine leukosis virus, compared with 1% of the beef cattle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Molecular characterization of foot-and-mouth disease virus isolated from ruminants in Taiwan in 1999-2000

In 1999, 10 sporadic outbreaks of cattle foot-and-mouth disease (FMD) occurred in Taiwan. By the time, infection was limited to the Chinese yellow cattle (a native species of beef cattle in Mainland China), which did not develop vesicular lesions under field conditions. Five viruses isolates obtained from individual farms were confirmed to be the serotype O FMD virus (O/Taiwan/1999). During January-February 2000, however, this virus has spread to dairy cattle and goat herds, causing severe mortality in goat kids and vesicular lesions in dairy cattle. Partial nucleotide sequence of the capsid coding gene 1D (VP1) was determined for the virus isolates obtained in this study. Phylogenetic analysis of the VP1 sequences indicated that the O/Taiwan/1999 viruses shared 95-97% similarities to the virus strains isolated from the Middle East and India. The species susceptibility of the O/Taiwan/1999 virus was experimentally studied in several species of susceptible animals, showing that the virus did cause generalized lesions in dairy cattle and pigs, however, it would not cause vesicular lesions on the Chinese yellow cattle and the adult goats. These studies suggested that the O/Taiwan/1999 virus was a novel FMD virus of Taiwan and it presented various levels of susceptibility in cattle species.     

Epidemiology of bovine malignant catarrhal fevers,a review

The mode of transmission of malignant catarrhal fever virus (MCFV) from wildebeest to cattle has been obscure for some time. Recent studies on the virus shedding patterns of wildebeest have revealed that MCFV occurs in nasal and ocular secretions of young wildebeest in a stable, cell-free state. Such cell-free virus is not found in the secretions of MCFV infected cattle.The findings indicate that MCFV is transmitted from wildebeest to cattle as cell-free virus shed in the secretions of young wildebeest calves and may explain the non-contagious nature of the disease in cattle.The mode of transmission of sheep-associated MCF has not been determined because the causative agent of this condition has not been isolated from either carrier sheep or sick cattle.