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Biomedical subjects

J H Dufty

Publications and source records attributed to J H Dufty.

At least 19 recordsLinked to original sources
PubMed1991

Cross-protective immunity and the serological classification system for Bacteroides nodosus.

The relationship between the serological classification system for serogroup B and for serogroup H of Bacteroides nodosus and cross-protection between subgroups within these serogroups was examined. Protection against ovine footrot following vaccination was achieved against other subgroup strains provided sufficient cross-reactive antibody was induced by shared pilus antigens. Within serogroup B, better cross-protection against one subgroup was obtained with a pili vaccine than a whole cell vaccine which correlated with higher pilus antibody titres induced by the former. For serogroup H, a lack of cross-protection and serological reactivity between subgroups was demonstrated, which indicates that the prototype strain of subgroup H2 should be designated a new serogroup.

Agglutination Tests↗
PubMed1990

The expression of bovine lymphocyte antigen and response of Hereford cattle to vaccination against Boophilus microplus.

The influence of the bovine lymphocyte antigen MB5 on the immune response of Hereford cattle to antigens of the tick (Boophilus microplus) was examined. Groups of cattle having or lacking the antigen MB5 (MB5+ and MB5-, respectively) were vaccinated with either soluble extracts of the gut membrane of adult ticks and adjuvant or injected with adjuvant alone. Cattle vaccinated with soluble gut membrane were significantly protected from two challenges with ticks. Protection against ticks was not significantly affected by the presence or absence of the lymphocyte antigen MB5. Similarly, no differences occurred in antibody levels (measured by enzyme-linked immunosorbent assay) and cellular responses (measured by lymphocyte blastogenesis assay) in MB5+ and MB5- groups to gut antigen.

Animals↗
PubMed1990

Studies on the bovine major histocompatibility class I and class II antigens using homozygous typing cells and antigen-specific BoT4+ blast cells.

Animals were identified from two sire lines as being homozygous for the class I bovine lymphocyte antigen (BoLA-A) w23. These animals were also shown to be homozygous for class II antigens (BoLA-D) which, however, differed between the two sire lines. Lymphocytes from these animals were then used either as stimulator cells in one-way mixed lymphocyte reactions (MLR) with all animals in the herd carrying the w23 antigen or as antigen presenting cells to bovine T4+ cell blasts. It was shown that, within each sire line, the genes encoding the MHC class I and class II antigens were closely linked. There were no detected recombinations between the MHC class I and class II regions nor within the BoLA-D region responsible for mixed lymphocyte reactivity. MLR typing of MHC class II antigens correlated with the results from T-lymphocyte proliferation studies. Cells from these cattle, which are homozygous at the class I and II MHC loci but differ in the class II antigen expressed, could be used to type the BoLA-D of other cattle.

Animals↗
PubMed1990

Electroejaculation in goats.

A comparison was made of a sine-wave and a pulse-wave electroejaculator for the collection of semen from male goats. Six animals were ejaculated once, using one or other instrument and 8 were ejaculated with each device with an intervening rest period. Comparing the sine-wave with the pulse-wave equipment, the mean total number of sperm collected was 5.3 x 10(9) and 2.1 x 10(9) cells respectively, in the first experiment and 4.0 x 10(9) and 1.0 x 10(9) cells, respectively, in the second experiment. In the latter experiment, a significant difference (p less than 0.05) was found in the sperm concentration, which was higher with the sine-wave generator. This instrument, with controlled output, was considered less stressful to the animal.

Animals↗
PubMed1989

A positive association between resistance to ovine footrot and particular lymphocyte antigen types.

The distribution of 12 Class I ovine lymphocyte antigens (OLA) was examined in 4 flocks of sheep vaccinated against and/or challenged with Bacteroides nodosus, the transmitting agent of footrot. In a flock of 47 Corriedales in New Zealand, which had been specially bred for resistance to footrot, a higher frequency (70.2%) of OLA type SY6 was found compared with 42.9% in 49 unselected Corriedale sheep (P = 0.001). The serum antibody response of 12 selected Corriedale ewes was compared with that of 12 unselected ewes of the same age after vaccination with a multivalent footrot vaccine and the selected ewes had significantly (P = 0.01) higher agglutinin titres than the unselected ewes, 7 weeks after vaccination. In 3 trials involving 108, 120 and 135 Australian Merinos in Victoria, SYlb was associated with a reduction in the number of feet affected with severe footrot (P = 0.05, P = 0.01, P = 0.02) and in 2 of the trials there was a relationship between SY6 and high vaccinal agglutinin titres. This SY6 effect was evident in the first trial 31 days after primary vaccination (P = 0.05) and again 20 days later after secondary vaccination (P = 0.01). In the second trial, when the sheep were vaccinated 49 days after challenge, an association was again found between SY6 and high agglutinin titres (P = 0.05) after primary but not after secondary vaccination. Exposure of 157 vaccinated Merino rams to B. nodosus during a footrot outbreak in New South Wales also showed an association between low infection and SY6 and SYlb.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

An analysis of cellular proliferation, and synthesis of lymphokines and specific antibody in vitro by leucocytes from immunized cattle.

The relationships between the production of lymphokines, cellular proliferation and antibody synthesis by immune bovine PBL in vitro was examined to identify the cellular reactions responsible for differences in the titres of serum antibodies in calves from selected sire lines and MHC Class I phenotypes. Leucocytes from 22 calves immunized with ovalbumin and DNP-BSA proliferated specifically in vitro in the presence of 1-10 micrograms/ml ovalbumin 7-28 days after the second vaccination. Significant correlations between the production of IL-2, IFN-gamma and maximum proliferation were observed for the total group. The quantity of specific antibody produced when PBL were incubated alone or with 10(-1)-10(-2) micrograms/ml ovalbumin was also correlated significantly with the maximum proliferation and the serum antibody titre between 7 and 14 days. Anti-ovalbumin IgG was also synthesized in MLRs where the quantity of antibody was significantly correlated with the magnitude of proliferation. The responses in vitro to DNP-BSA were too low to provide meaningful comparisons. The results indicate that at intervals during the period of increasing serum titres, events in the bovine antibody response in vivo can be replicated in vitro. In addition, assays for proliferation, IL-2 or gamma-IFN, or specific antibody can be used to assess the magnitude of the immune response in vivo in experimental groups of cattle. Significant sire line differences in the serological responses to ovalbumin were observed but DNP-BSA was a poorer antigen and differences in the responses to this antigen were not significant. However, the sire line differences in vivo were not reflected in vitro in proliferative and lymphokine assays; only the production of antibody in vitro was significantly correlated with the in vivo serum titre.

Animals↗
PubMed1987

A functional and biochemical analysis of bovine class II MHC antigens using monoclonal antibodies.

Monoclonal antibodies (MAbs) reacting with bovine (2) ovine (3), murine (1) or human (1) Class II MHC antigens were examined for reactivity with bovine peripheral blood leucocytes (PBL) and lymph node cells (LNC) by immunofluorescence, immunoprecipitation and the capacity to inhibit mixed lymphocyte responses (MLR), lectin- and antigen-induced blastogenesis. The 6 MAbs identified comparable percentages of Class II positive lymphocytes in PBL (40.8 to 54.2%) and LNC (6 to 11.5%) regardless of BoLA-A phenotype. Immunohistological staining of Class II MAb was localized principally to the lymphoid follicles in lymph nodes and to isolated epithelial reticular cells in the thymus. The anti-Class II MAb immunoprecipitated alpha- and beta- chains of 26-29K and 32-34K, respectively. These MAb inhibited proliferative responses in the MLR by between 25 and 74%, and diminished blastogenesis induced by specific antigens (purified protein derivative + PPD and ovalbumin) and B-lymphocyte mitogens (PPD, lipopolysaccharide and dextran sulphate) by between 45 and 75%, regardless of BoLA-A phenotype. In contrast, proliferation in response to concanavalin A and phytohaemagglutinin were unaffected by the anti- Class II MAb. Similarly these MAb did not affect lysis by cytotoxic T-lymphocytes, the activity of which was depressed by anti-Class I MAbs and monospecific alloantisera.

Animals↗
PubMed1987

Breed differences in the frequency of bovine lymphocyte antigens.

Lymphocytes from 1,564 cattle of 18 breeds and cross-bred groups in Australia were tested for major histocompatibility system class 1 antigens. Gene frequencies were calculated for the Angus, Belmont Red, Brahman, Hereford and Holstein-Friesian breeds. There were substantial differences among these breeds in antigen and gene frequency. There were striking differences among all 18 breeds in the presence or absence of certain antigens. Two antigens, CA13 and CA36, were strongly associated in Hereford cattle but occurred independently of each other in the other breeds.

Animals↗
PubMed1986

Studies into immunisation of cattle against interdigital necrobacillosis.

Calves were immunised with fractions of Fusobacterium necrophorum incorporated in mineral oil adjuvant and then each foot was experimentally exposed to interdigital necrobacillosis (foot abscess) by subcutaneous injection of homologous organisms through the interdigital skin. The number of cells from an 18 h liquid culture that might be expected to cause 50% of the feet of control calves to develop marked swellings following subcutaneous injection was shown to be approximately 2.2 X 10(8) cells. Immunity was shown to be associated with antigens that were located in the supernatant of the culture, and which may be identical with or closely associated with the exotoxins.

Abscess↗
PubMed1986

Antibodies to ovine lymphocytes exist in bovine alloantisera.

Forty-six percent of 149 reagents against class 1 antigens of the bovine major histocompatibility system reacted with lymphocytes from 1 or more sheep in a microlymphocytotoxicity test. The reactions fell into six groups. The majority of antisera defined an antigen present on both erythrocytes and lymphocytes. This antigen is probably the R blood group antigen and the reactions were unrelated to the presence of anticlass I activity and are probably due to the additional presence of antibodies of R specificity. The other antigens are not identical to any of the 14 red blood cell factors or seven lymphocyte antigens examined, nor did they correspond to any of the class I bovine lymphocyte antigens defined by the alloantisera.

Animals↗
PubMed1985

Studies on the bovine lymphocyte antigens and the production of lymphocytotoxic antibodies by parous cattle.

Studies were carried out to determine the time of appearance, frequency, titre and specificity of lymphocytotoxic antibodies in the plasma of parous Hereford cattle. Cytotoxic antibody was first detected in a small proportion (3/62 = 4.8%) of primigravid cattle during the last third of pregnancy. Titres were low (neat or 1 in 2) at this time and decreased in one animal so that antibodies were not detectable in samples obtained on the day of calving or 9 days beforehand. Following parturition, the proportion of primiparous cattle producing lymphocytotoxic antibodies increased markedly and reached a maximum value (8/19 = 42.1%) during the third month post partum. Antibody levels also rose over the same period. An increase in the parity of the dam also resulted in an increase in the proportion of cattle with lymphocytotoxic plasma. These antibodies appeared earlier in pregnancy, were at a higher titre and had a wider specificity than those found in primigravida. Non-foetally stimulated antibody was detected in 4 cattle. In one plasma sample, lymphocytotoxic activity was present prior to mating, and in the 3 others it was not directed against cells from either the bull to which the dam was mated or the calf produced by the sire and dam.

Animals↗
PubMed1985

A comparison of bovine lymphocyte antigens.

In Canberra, 31 antigens have been described on the surface of bovine lymphocytes. Seven antigens are subgroups of other antigens. Eleven antigens are similar to the eleven antigens which have been described in Melbourne. Fourteen antigens are similar to twelve international-workshop antigens and two European-workshop antigens.

Animals↗
PubMed1985

Cultural characteristics and virulence of strains of Fusobacterium necrophorum isolated from the feet of cattle and sheep.

Sixty-one isolates of Fusobacterium necrophorum were recovered for study. Thirty-one were obtained from lesions of foot abscess in cattle (25) and sheep (6), 28 were from interdigital lesions in cattle and 2 were from the normal interdigital skin of cattle. The majority of isolates from lesions of foot abscess were virulent, belonged to biotype AB (Fievez 1963), produced flat, irregular shaped, greyish colonies and haemolysis on blood agar, and grew as turbid filamentous suspensions in liquid media. They produced a soluble exotoxin, a leucocidin, and were pathogenic for cattle and mice. Virulent isolates also produced a haemolysin which most readily lysed bovine, equine and chicken erythrocytes; those from sheep were less susceptible while those of rabbit and pig were the most resistant. Isolates recovered from lesions of the feet not classified as foot abscess and from clinically normal feet were predominantly of the B biotype and caused few experimental lesions, produced convex, round, yellow colonies, flocculated and sedimented while growing in liquid medium and produced little or no haemolysin or leucocidin. Routine differentiation between virulent and non-virulent bovine isolates of F. necrophorum could be achieved by assessing the colour, morphology, and degree of haemolytic activity of colonies grown on blood agar.

Abscess↗
PubMed1977

Studies on the transmission of Tritrichomonas foetus.

Although 2 experiments showed that non-infected bulls can passively transmit Tritrichomonas foestus from infected to non-infected cows during mating, the rates of transmission were low. The results of the second experiment, in which time intervals between services were recorded, suggested that T. foetus was most likely to become established in previously non-infected cows when the interval was less than 20 minutes. Application of 2 X 10(6) active cells of T. foetus to the vulva failed to cause genital infection in 10 cows.

Animals↗