PubMed Health⌕ Search

Biomedical subjects

A W Lepper

Publications and source records attributed to A W Lepper.

15 recordsLinked to original sources
PubMed1992

The protective efficacy of pili from different strains of Moraxella bovis within the same serogroup against infectious bovine keratoconjunctivitis.

Three groups of ten calves were each immunised with a total of 400 micrograms pili prepared from three separate strains of Moraxella bovis in Alhydrogel-oil adjuvant as two divided, equal doses 21 days apart. Groups 1 and 2 each received a monovalent vaccine made from strain 4L and S276R respectively, which belonged to pili serogroup A. Group 3 received vaccine made from pili of strain Maff1, belonging to serogroup F. A further group of ten calves served as non-vaccinated controls. Calves in groups 1 and 2 had developed serogroup A-specific antibody and those in group 3 developed serogroup F-specific antibody, and some evidence of cross-reacting antibody was also detected when measured by an agglutination test using formalin-killed piliated cells of serogroup A strain 4L. Although antibody titres measured against purified pili by ELISA were highest with homologous serogroup antigens, cross-reactive titres to shared epitopes of M. bovis pili were also detected by this method. Ocular challenge of the 40 calves with virulent M. bovis of serogroup A strain S276R was carried out 14 days after the second vaccine dose. All non-vaccinated calves developed infectious bovine keratoconjunctivitis (IBK). The percentage protection in groups 1 (strain 4L) and 2 (strain S276R) was 60% and 80% respectively (P less than 0.05), with mean lesion scores of 0.7 and 0.3 out of a possible 6.0. The percentage protection of calves in group 3 (strain Maff1) was only 30%, with a mean lesion score of 1.4 compared with 2.2 for non-vaccinated controls. The present findings, together with other evidence indicating that immunity to IBK is serogroup-specific, suggest that inclusion of pili from one representative strain from each of the seven Australian and British serogroups in a polyvalent, subunit vaccine should effectively protect the majority of cattle against IBK caused by most field strains of M. bovis encountered in Australia and the United Kingdom.

Animals↗
PubMed1991

A unified serotyping scheme for Moraxella bovis.

Fifty-three Australian, seven British, two American and two New Zealand isolates of Moraxella bovis were classified into seven serogroups on the basis of their variable fimbrial (pilus) antigens using whole cell slide agglutination (SA), enzyme-linked immunosorbent assays (ELISA) and tandem-crossed immunoelectrophoresis (TCIE). Although results of serogroup classification by SA and ELISA were identical in 68.7% of isolates, it was found necessary to resolve the discrepancies between the two systems using TCIE. Results suggest that world-wide variation in the potentially host-protective fimbrial antigens of M. bovis may be relatively limited. It is proposed that the previous numerical classifications of British and Australian serogroups are appropriately amalgamated as a result of this latest study and are designated as serogroups A to G inclusive. A protocol for the further serotyping of fresh, fimbriate isolates of M. bovis is suggested.

Agglutination Tests↗
PubMed1990

Characterization of the pilin gene of Moraxella bovis Dalton 2d and expression of pili from M. bovis in Pseudomonas aeruginosa.

The pilin gene of Moraxella bovis Dalton 2d was isolated by cloning in Pseudomonas aeruginosa. The nucleotide sequence of this gene encodes a prepilin of 156 amino acid residues. When high levels of pilin were expressed from the gene in P. aeruginosa, by using the pL promoter of bacteriophage lambda inserted upstream of the coding sequence, pili which were indistinguishable from pili of M. bovis were produced.

Amino Acid Sequence↗
PubMed1977

The use of bovine PPD tuberculin the single caudal fold test to detect tuberculosis in beef cattle.

The efficiency of 2 different doses of bovine PPD tuberculin was compared using the caudal fold test for the detection of tuberculosis in beef cattle. Two matched groups of 98 cattle were selected on the basis of their reactivity to HCSM tuberculin. Cattle in each group were tested with a singl 0.1 ml dose of bovine PPD tuberculin containing either 0.1 mg or 0.2mg bovine PPD respectively. Two further groups of 100 young stock from a herd with an incidence of tuberculosis of less than 0.1% were selected as controls. Tests were interpreted subjectively by palpation and observation and objectively by caliper measurement at 48, 72 and 96h. All cattle were examined post mortem for the presence of visible lesions. The 0.2 mg dose of PPD detected 95% tuberculous cattle and caused false-positive reactions in 19% of cattle without lesions. The 0.1 mg dose detected 80% of tuberculous cattle and caused 11% false-positive reactions. No visible lesions of tuberculosis were found in either of the control groups although 11% reacted to 0.2 mg and 5% to 0.1 mg bovine PPD at 72h. The optimum time for reading tuberculin tests was found to be in the period 48 to 72h after the injection of bovine PPD and subjective interpretation was more efficient than caliper measurement as a means of detection of tuberculous cattle. The 0.2 mg dose of bovine PPD was found to be more specific than HCSM tuberculin.

Animals↗
PubMed1977

Anergy to tuberculin in beef cattle.

Various aspects associated with anergy to tuberculin were investigated in a total of 75 tuberculous cattle. Forty-six (59%) had single lesions and 32 (41%) had multiple lesions. Forty-three (55.1%) had lesions in the lungs or associated lymph nodes and 23 (29.5%) showed multiple involvement of these tissues. Nine anergic cattle had generalised tuberculosis. Histological examination of lesions from 38 animals showed that the majority were of the progressive type. When bovine PPD tuberculin was used more cattle were anergic to the 0.1 mg than to the 0.2 mg dose and fewer tuberculous cattle were detected with either dose if tests were read at 96 h rather than 72h. Other factors thought to contribute to anergy are discussed with special reference to its relative importance in cattle with pulmonary infection.

Animals↗
PubMed1977

Serological responses in experimental bovine tuberculosis.

Five two-year-old heifers were each inoculated intravenously with 0.02 mg M. bovis strain AN5. Clinical, haematological and microbiological observations were made during the course of the experiment and antibody levels were measured before and after infection by means of the indirect immunofluorescent antibody (IFA) and bentonite flocculation tests. All cattle developed M. bovis infection varying in severity from peracute tuberculous pneumonia resulting in death within 33 days to chronic progressive generalised tuberculosis. Only cattle developing peracute or acute forms of tuberculosis showed marked haematological changes characterised by leucopenia with lymphopenia. Bacteraemia was detected in the two cattle with peracute tuberculosis 22 days after infection. Anti-mycobacterial antibody was detected after infection in all cattle but fluctuated markedly during the course of the disease. Of a total of 61 serum samples examined from all cattle after inoculation with M. bovis, only 38 were positive to the IFA test and 30 to the bentonite flocculation test. Only 18 were positive to both tests at any one time. IgM was the predominant type of anti-mycobacterial antibody detected by the IFA test and this was found to cross-react with M. avium in almost every sample.

Animals↗
PubMed1977

Tuberculin sensitivity of cattle inoculated with atypical mycobacteria isolated from cattle, feral pigs and trought water.

Each of 12 cattle was inoculated either subcutaneously and intradermally or into a mesenteric lymph node with 1 of 8 species of liver atypical mycobacteria isolated from cattle, cattle trough water and feral pigs. Seventy-eight days after inoculation the cattle were tuberculin tested with bovine PPD, avian PPD and homologous heat-concentrated syntheic medium tuberculins. They were killed 85 days after inoculation. Organisms were cultured from caseous granulomas at all sites in cattle inoculated with M. avium serotype 2. M. simiae was recovered from a granuloma at the subcutaneous site. Acid-fast bacilli were isolated from the mesenteric lymph node inoculated with trough water organisms. At 72 h, all the cattle had produced skin reactions of 4 mm or more to the homologous tuberculins and all except 1 produced a similar response to avian PPD. Only isolates of bovine origin sensitised cattle to bovine PPD to this degree, and these reactions were less than the corresponding response to avian PPD.

Animals↗
PubMed1977

Comparison of techniques for measuring the local and systemic responses to tuberculin in cattle.

Thermography of tuberculin skin reactions in cattle sensitized with Mycobacterium avium, Mycobacterium bovis, or Mycobacterium paratuberculosis was rapid and sensitive, but was not as specifically related to the homologous sensitization as was increased skin thickness at 48 and 72 hours. Systemic temperature responses were more completely monitored by radiotelemetry of intraperitoneally located temperature transmitters than by rectal thermometry, but the temperatures indicated by the 2 methods were nearly identical. The intraperitoneal transmitters showed that the systemic responses consisted of 1, 2, or 3 temperature peaks, and in 1 animal which had previously been exposed to a heterologous tuberculin, a hypothermic response developed. The systemic temperature responses were more specifically related to homologous sensitization than were dermal responses, but were more cumbersome to measure.

Animals↗
PubMed1976

Peroxidase staining in elicited and nonelicited mononuclear peritoneal cells from BCG-sensitized and nonsensitized mice.

The peroxidase (PO) activity in nonelicited macrophages and in casein-elicited monocytes, obtained from peritoneal cavities of nonsensitized and BCG-sensitized mice and cultivated on glass for 1 or 2 h, was studied by light and electron microscopy, using the 3,3'-diaminobenzidine technique. These two types of glass-adherent peritoneal cells differed in PO activity. In macrophages, PO activity was predominantly in the nuclear envelope, rough endoplasmic reticulum, and occasionally in vesicles of the Golgi apparatus. In monocytes, PO activity was confined to cytoplasmic dense bodies resembling lysosomes, and was greater at 10 and 24 h after elicitation than at 96 h. The BCG sensitization did not significantly alter the proportion of cells with PO-positive granules in macrophages or monocytes from that observed in nonsensitized mice. From its lysosomal site, the PO in monocytes could come into contact with those microorganisms whose ingestion by these cells was followed by phagolysosome formation.

Animals↗
PubMed1976

Immune mechanisms affecting bovine leucocytes during suppression of tuberculin skin sensitivity in cattle.

Complete desensitization to tuberculin skin-testing (anergy) was produced in cattle by repeated intravenous injections of living BCG organisms into animals sensitized by a prior subcutaneous dose of BCG. Two levels of desensitization were produced; complete desensitization following 10 i.v. doses and partial desensitization following 5 i.v. doses of 100 mg BCG. Intradermal tuberculin testing at the end of the experiment stimulated the appearance of reactive blood lymphocytes in sensitized cattle as measured by in vitro 3H-thymidine uptake. The cattle which were partially desensitized showed this response but the completely desensitized cattle did not. Reactivity of blood lymphocytes in vitro to PHA and Brucella abortus antigen was not depressed in the anergic cattle. Serum antibody titres to BCG polysaccharide, PPD, or whole BCG organisms showed remarkably little change during the i.v. desensitizing injections of BCG. Differential blood leucocyte counts also remained within normal limits during this period. The production of MIF by blood lymphocytes from the anergic cattle appeared to be unimpaired. Using 3H-thymidine uptake by lymphocytes from sensitized cattle did not inhibit lymphocyte stimulation with tuberculin. It was concluded that the lack of tuberculin sensitized lymphocytes in the blood of anergic cattle may have been due to their removal from the recirculating pool and their continued suppression in lymphoid tissue.

Animals↗
PubMed1976

Experimental bovine Trichophyton verrucosum infection. Comparison of the rate of epidermal cell proliferation and keratinisation in non-infected and reinoculated cattle.

The rate of epidermal cell renewal in normal bovine skin and that reinoculated with Trichophyton verrucosum was measured using a radioautographic technique. The transit times of both nucleated and fully keratinised cells were measured in sequential biopsy samples removed at predetermined periods after intradermal inoculation with radio-labelled isotopes. The total time taken for cells of the basal layer to travel to the point of desquamation in the stratum corneum was 18 days in normal cattle. In similar areas on cattle that had been reinoculated with T verrucosum the total epidermal cell renewal time was reduced to 12 days. Increased protein synthesis, as measured by incorporation of radio-labelled nucleoside was evident in basal cells within 24 h of reinoculation with the fungus. The nucleated epidermal cell thickness had almost doubled in areas of reinoculated skin within 72 h and increased cell proliferation was maintained for at least 10 days. Desquamation of the thickened stratum corneum had occurred within seven days of reinoculation with the fungus.

Animals↗
PubMed1975

The indirect fluorescent antibody test for the detection of circulating antibodies in bovine tuberculosis.

Indirect fluorescent antibody (IFA) tests were carried out on a total of 545 individual serums from beef cattle just before tuberculin testing, using specific FITC-anti-bovine IgG and IgM conjugates. Phenol-killed M. tuberculosis (H37Rv strain) or field strains of M. bovis and M. avium were used as antigenic substrates. All cattle were examined at abattoirs for the presence of tuberculous lesions. A statistically significant difference (p less than 0.001) was found between the number of cattle with serums containing IgM and those with IgG antibody to M. bovis. The majority of cross-reactions that occurred with M. avium was due to IgM antibody. The IFA test using M. bovis and both antiglobulin conjugates detected 77% of cattle with visible lesions of tuberculosis, while the single intradermal caudal fold tuberculin test detected 83%. The IFA test detected 25 of 31 cattle with lesions that failed to react in the tuberculin test. The tuberculin test gave apparently false positive reactions in 6.2% and the IFA test gave false positive reactions in 21.2% of all cattle. The IFA test is of potential use as a further aid in the detection of tuberculous cattle that fail to react to tuberculin. It offers no advantage over the tuberculin test for the detection of all forms of the disease because it fails to detect a significant proportion of tuberculous cattle and produces an unacceptably high number of false positive results.

Animals↗