Clinical aspects of the bovine virus diarrhoea/mucosal disease complex in cattle.
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Animals↗
Biomedical subjects
J Brownlie
Publications and source records attributed to J Brownlie.
Importance of ovine cytotoxic T cells in protection against bluetongue virus infection.
In sheep, bluetongue virus (BTV) was shown to induce anti-BTV cytotoxic T lymphocytes (CTL) and their effect to be maximal around 14 days post inoculation (p.i.) of virus. Using cellular adoptive transfer techniques in monozygotic sheep, such cells were shown to partially protect animals from BTV challenge. A short-lived cross-protective mechanism was identified involving thoracic duct lymphocytes (TDL) and nonneutralising antibody. These observations suggest that T lymphocytes play an important role in protection against BTV and that current vaccine design based on in vitro serological typing of BTV can be improved.
Animals↗
Experimental production of fatal mucosal disease in cattle.
Three outbreaks of mucosal disease were investigated. Careful examination of 47 cattle that were persistently viraemic with bovine virus diarrhoea virus (BVDV) revealed no clinical disease, no or low levels of BVDV antibody and only non-cytopathic virus in their blood. The four animals with mucosal disease all showed clinical disease and both cytopathic and non-cytopathic virus in their blood. Following post mortem examination, there were particularly high levels of cytopathic virus in gut tissue. A hypothesis for the induction of mucosal disease is suggested. It states that animals become persistently infected with non-cytopathic virus following in utero infection and when, in post natal life, they become superinfected with a cytopathic virus, then mucosal disease ensues. The experimental reproduction of mucosal disease in support of this hypothesis is described.
Animals↗
Sheep lymphocyte antigens and scrapie.
The frequencies of 15 lymphocyte antigens were determined in 2 experimental flocks of Herdwick sheep derived from the same foundation stock. The Blue Flock had been bred for resistance, and the Red flock for susceptibility, to a standard dose of the SSBP/1 source of scrapie injected subcutaneously. Although there were marked frequently differences between the 158 Red flock and 51 Blue flock sheep tested these differences could be attributed to genetic drift. Within the Red flock no significant frequency differences were observed between 16 sheep which developed natural scrapie and their healthy flockmates. All Red flock lambs born in 1980 were injected subcutaneously with SSBP/1 scrapie; there was no difference in antigen frequency between the group which subsequently developed experimental scrapie (30) and the group which did not (21). The segregation of antigen haplotypes in the Red flock pedigrees showed no evidence of MHC linkage with either natural or experimental scrapie.
Alleles↗
A study of the role of cell-mediated immunity in bluetongue virus infection in sheep, using cellular adoptive transfer techniques.
The transfer of thoracic duct lymphocytes from sheep inoculated 14 days, but not 7 days previously with bluetongue virus into their monozygotic twin resulted in some protection from challenge with bluetongue virus. T cell enrichment of the 14 day thoracic duct lymphocyte population resulted in a similar effect, indicating the T cell basis of the observed protection. Animals recovered from infection with bluetongue virus type 3 and which received thoracic duct lymphocytes from an identical twin recently infected with the same bluetongue virus type were protected from challenge with bluetongue type 4. These observations suggest that T lymphocytes play an important role in protection against bluetongue virus.
Animals↗
Sheep lymphocyte antigens: a preliminary study.
Sera from 287 sheep were screened for cytotoxic antibodies against sheep lymphocytes. Forty four antisera were selected which provisionally define 13 lymphocyte antigens. The frequency of these antigens was studied in 305 sheep from 8 flocks of different breeds. Family studies confirm that inheritance of sheep lymphocyte antigens is controlled by the autosomal codominant genes of at least 2 linked loci.
Animals↗
Experimental infection of calves with two strains of bovine virus diarrhoea virus: certain immunological reactions.
Certain immunological responses of 4-6 month old calves experimentally inoculated with either cytopathic or non-cytopathic bovine virus diarrhoea virus (BVDV) were compared with those of uninfected control calves. The tests used to demonstrate the immunological responses were the transformation of lymphocytes by PHA mitogen, the percentage of lymphocytes with surface immunoglobulin, and the antibody titres induced by an intravenous inoculation of killed Brucella abortus. There were no significant differences between the two groups of calves and therefore, the mild experimental disease produced by BVDV did not appear to affect adversely the immunological response.
Animals↗
The influence of dietary iodine on iodine in the blood serum of cows and calves in the perinatal period.
Concentrations of total iodine (TI) and protein-bound iodine (PBI) in the blood serum of both cows and their neonatal calves were related to the iodine content of the diet fed to the cows. A group of six cows (group 1) fed a diet containing 0.6 ppm iodine had mean concentrations of TI and PBI of 4.1 and 3.4 microgram/100 ml respectively. A second group (group 2), fed a diet containing 4.6 ppm iodine, had concentrations of 33.8 and 7.6 microgram/100 ml of TI and PBI respectively. Calves of groups 1 and 2 had mean concentrations of TI of 21 microgram/100 ml and 96 microgram/100 ml respectively within 24 h of birth, but these concentrations declined markedly over a period of eight days. Evidence was obtained that the high concentrations of TI, and also of PBI, in neonatal calves relative to the concentrations in their dams resulted mainly from placental transfer rather than from the ingestion of colostrum.
Administration, Oral↗
Surface receptors for immunoglobulin on bovine polymorphonuclear neutrophils and macrophages.
Surface receptors for rabbit immunoglobulin (Ig) and bovine IgG1 were detected on bovine alveolar macrophages by the rosette technique. Receptors for bovine IgG2 were either absent from, or present at a low level on, the surface of these cells. In contrast, polymorphonuclear neutrophils from peripheral blood and milk were shown to have surface receptors for bovine IgG2 but not for bovine IgG1 or rabbit Ig.
Animals↗
The response of bovine lymphocytes from lymph and blood to phytohaemagglutinin.
Optimal conditions for stimulation of bovine lymphocytes by Phytohaemagglutin (PHA) were established in a microtitre assay. Lymphocytes from efferent duct lymph responded vigorously, with specific incorporation of 100,000 to 200,000 cpm/well, providing the conditions of cell culture are carefully controlled. Peripheral blood lymphocytes responded over a wider range of cultural conditions but optimal specific incorporation was usually only 40-100,000 cpm/well.
Animals↗
The effect of an intramammary infusion of endotoxin on the establishment of experimental mastitis by Streptococcus agalactiae in the cow.
An infusion of E. coli endotoxin (10 microgram) into the mammary gland of the cow 16 h before experimental infection with St. agalactiae prevented the establishment of mastitis. A clinical examination of the affected gland did not reveal signs of inflammation, all organisms were eliminated from the milk by 36 h after infection. Mammary glands not pretreated with endotoxin, and injected with the same number of viable streptococci, showed signs of severe inflammation the milk yield was reduced and the injected pathogen could be isolated from the gland for up to 14 days when sampling was discontinued. The injection of endotoxin alone produced a rapid increase in the cell count of the milk, there were some signs of inflammation and 80% of the cells in the milk were neutrophils. The cell counts in the milk remained above normal for 7-10 days. Untreated control quarters appeared to be unaffected by the injection of E. coli endotoxin into an adjacent quarter, on the other hand the injection of St. agalactiae into the adjacent quarter on the same side of the udder produced a cell response which reached a peak after 2 days and returned to preinoculation levels by the fourth day. No inflammation was observed in these control quarters and no streptococci were isolated from the milk.
Animals↗
The effect of an intramammary infusion of endotoxin on experimentally induced mycoplasmal mastitis.
The infusion of 10 microgram of endotoxin lipopolysaccharide from Escherichia coli into the mammary gland of four cows 16 h before inoculation with ureaplasmas did not prevent, or even diminish, the subsequent ureaplasmal mastitis. There was no reduction in the severity or duration of the inflammatory cell response in milk or in the clinical appearance of the resulting mastitis. Also, the excretion of ureaplasmas was not reduced. A similar experiment with Mycoplasma dispar in two cows demonstrated that endotoxin was again ineffective in preventing the mastitis. Furthermore, there was some indication that the proliferation and excretion of this mycoplasma was enhanced in endotoxin-treated quarters.
Animals↗
Interaction of certain bovine immunoglobulins with complement in a single radial haemolysis system.
Bovine IgG1, IgG2, and IgM initiated haemolysis by bovine complement. With guinea pig complement bovine IgG1 and IgM appeared effective, but bovine IgG2 was much less effective. Single radial haemolysis systems using guinea pig complement to measure bovine antibody are likely to detect predominantly IgG1 and IgM. However, in vivo IgG2 should activate bovine complement.
Animals↗
Pathogenicity of certain Mycoplasma species in the bovine mammary gland.
Strains of three of the species of mycoplasmas isolated from pneumonic calf lungs, Mycoplasma dispar, Mycoplasma bovirhinis and Acholeplasma laidlawii, were inoculated into the bovine mammary gland. Pathogenicity of the species was monitored by counting the inflammatory cells and mycoplasmas in milk. Six of the seven M dispar strains produced clinical mastitis, but the seventh strain, Vic12, was apparently avirulent. The four strains of M bovirhinis caused subclinical mastitis. None of the four strains of A laidlawii multiplied and they produced only a transient cell response in the milk.
Acholeplasma laidlawii↗
Presence of a dialysable fraction in normal bovine whey capable of killing several species of bovine mycoplasmas.
Most normal bovine whey samples contain a fraction that survives heating at 56 degrees C. for 30 min., passes through a dialysis membrane and kills a maximum of seven out of ten of the different bovine mycoplasma species tested. Some whey samples appear more active than other but not all affect the same strains of mycoplasma indicating some specificity in their action. Absorption of the active factor from whey by heterologous and homologous mycoplasmas and by erythrocytes was observed. Binding of the factor to mycoplasmas appears to be temperature-dependent and non-specific, but subsequent mycoplasmacidal action shows some specificity.
Absorption↗
Localized immunity in experimental bovine mastitis caused by Mycoplasma dispar.
Development of immunity to reinfection with Mycoplasma dispar occurred in the bovine mammary gland and appeared to be confined to the quarter or quarters previously infected with this mycoplasma; it was not generalized throughout the gland. Immunity followed the inoculation of virulent strains of M. dispar but not of an avirulent strain. The immunity engendered protected against both homologous and heterologous strains of M. dispar. Challenge of immune quarters with virulent M. dispar resulted in a transient polymorphonuclear cell response greater than that observed in previously uninoculated quarters.
Animals↗
Mycoplasmacidal activity of bovine milk for T-mycoplasmas.
Normal bovine milk and whey was mycoplasmacidal for 6 of the 13 strains of bovine T-mycoplasmas examined. The in vitro assay used also demonstrated no killing of the human, canine and simian T-mycoplasma strains after 4 hr. incubation. However, there appeared to be some cow-to-cow variation in possession of this activity, and following E. coli endotoxin stimulation of the mammary gland the activity was considerably reduced.Whey from three normal cows was fractionated on a Bio-Gel A 1.5 m. column and the mycoplasmacidal activity of the resulting five peaks assayed. Only the second peak, peak B, contained activity and was characterized as the only peak containing bovine IgA. The active component in whey, however, was found to be heat stable at 60 degrees C. for 60 minutes and to pass through a dialysis membrane. This is inconsistent with it being immunoglobulin.
Animals↗
Immunity in experimental T-mycoplasma mastitis.
Immunity to reinfection with the homologous T-mycoplasma strain has been demonstrated in the bovine mammary gland. This immunity was generalized throughout the udder and was not confined to previously infected quarters. Two out of three cows which were immune to reinfection with the homologous strain were not immune to reinfection with a serologically distinct T-mycoplasma strain. Animals varied in their ability to resolve experimental mastitis with T-mycoplasmas: those which resolved the initial infection without antibiotic therapy were immune to challenge with the homologous strain, but those which needed to be given antibiotics to clear the first infection were not all immune to such challenge.
Animals↗