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A C Wardlaw

Publications and source records attributed to A C Wardlaw.

13 recordsLinked to original sources
PubMed1992

Multiple discontinuity as a remarkable feature of the development of acellular pertussis vaccines.

Development of the Japanese acellular pertussis vaccines (APVs) of the 1980s involved six procedural or conceptual features that were discontinuous with the then-accepted views of how pertussis vaccines should be made and tested. These discontinuities were: modification of the standard intracerebral mouse test for protective potency; use of culture supernates, rather than cells, of Bordetella pertussis as the feedstock for antigen purification; use of haemagglutination as a measure of protective antigen(s); identification of pertussis toxin (PT) as the main protective antigen; complete inactivation of the biological activities of PT by formalin; and the use of a single strain of B. pertussis. Several of these discontinuities had long precedence in the pertussis literature, but the original observations had not been incorporated into the mainstream of pertussis vaccinology and were therefore 'premature'. The APVs, purified from culture-supernates, emerged after a long period of unsuccessful research on the split-cell pertussis vaccines, i.e. those derived from the bacterial cells themselves. There is a brief discussion of why APVs have taken so long to obtain acceptance outside Japan, and of how the listed discontinuities may be explicable in terms of antigen processing by the immune system. General lessions, applicable to vaccines for other infectious diseases, may be learned from this account of how APVs have evolved from whole-cell pertussis vaccines.

Animals↗
PubMed1991

Assay of Bordetella pertussis heat-labile toxin with human embryonic lung cells.

An assay has been developed for Bordetella pertussis heat-labile toxin (HLT) based on morphological alterations in certain human embryonic lung (HEL) cell lines. Eighteen cell lines from human and other sources were tested but only two, MRC-5 and HELu2, were responsive to HLT. Confluent monolayers of the cells contracted within 24 h of exposure to the toxin, but without loss of viability during incubation for a further 3 days. The effect of HLT was quantitated by scoring the extent of morphological change, and by the decrease in Giemsa staining of the cell monolayers, as measured on an ELISA plate reader. This cell culture assay for HLT was more sensitive than lethality titration in mice but the dose-response curve had a lower slope. The specificity of the response was established by comparing unheated HLT with HLT heated at 56 degrees C, and with extracts from transposon-insertion mutants of B. pertussis which were deficient in HLT. Purified preparations of pertussis toxin and B. pertussis lipopolysaccharide gave no morphological response even at high doses.

Animals↗
PubMed1991

Growth and survival of Bordetella bronchiseptica in natural waters and in buffered saline without added nutrients.

Bordetella bronchiseptica showed increases in viable count when incubated in phosphate-buffered saline (PBS), in reagent-grade water, and in local lake and pond waters, all without added nutrients. Within 48 to 72 h at 37 degrees C in PBS and in lake and pond waters, stationary-phase populations of around 2.7 x 10(6) CFU/ml developed from washed B. bronchiseptica inocula of around 2 x 10(3) CFU/ml. Increases in CFU on the order of five- and eightfold, respectively, were observed in reagent-grade water and in seawater from the same sizes of inocula. The organisms remained viable for at least 3 weeks in PBS and in lake waters at 37 degrees C. The possibility that carry-over of nutrients was responsible for growth was discounted by showing serial transfer of B. bronchiseptica in PBS under conditions in which Escherichia coli tested in parallel rapidly died out.

Bordetella↗
PubMed1979

Degradation of bacterial lipopolysaccharide by gut juice os the snail Helix pomatia.

Lipopolysaccharides from several bacteria were selectively degarded by gut juice of the snail Helix pomatia with extensive loss of anticomplementary activity and changes in the electrophoretic pattern in polyacrylamide gels. The gut juice had little effect on ketodeoxyoctonate content or immunodominant sugars. The lipid A moiety of the lipopolysaccharide appeared to be the main site of attack.

Animals↗
PubMed1979

Degradation of bacterial lipopolysaccharide by the slime mould Physarum polycephalum.

A strain of the acellular slime mould Physarum polycephalum degraded lipopolysaccharides (LPS) from a variety of bacteria. The anticomplementary (AC) activity of LPS was greatly reduced, as was the content of lauric, myristic, and palmitic acids, and the ability to sensitize erythrocytes to agglutination by antibody. These results indicate that Physarum has enzymes which reduce the lipid A moiety of LPS. In contrast, 2-keto-3-deoxy-D-manno-actanoic acid (KDO), immunodominant sugars, and beta-hydroxymyristic acid were scarcely affected. Both supernates and plasmodial extracts of Physarum had LPS-degradative activity and were able to attack both purified LPS and LPS in killed bacteria.

Biodegradation, Environmental↗
PubMed1979

Loss of adjuvanticity in rats for the hyperacute form of allergic encephalomyelitis and for reaginic antibody production in mice of a phenotypic variant of Bordetella pertussis.

The adjuvanticity of a phenotypic (C-mode) variant of B. pertussis, known to be deficient in certain immunological and physiopathological properties, was compared to that of the normal (X-mode) strain. The X-mode vaccine was a potent adjuvant for induction of hyperacute experimental allergic encephalomyelitis to guinea-pig spinal cord in Lewis rats whereas C-mode vaccine was inactive. X-mode vaccine was also highly active in the induction of reaginic (both IgE and IgGl) antibodies to ovalbumin in mice while C-mode vaccine caused only a transitory increase in the IgE level. These data support the view that an adjuvant component of B. pertussis, which is probably identical with the histamine-sensitizing and leukocytosis promoting factor, is much diminished in C-mode cells while the lipopolysaccharide adjuvant remains unchanged.

Adjuvants, Immunologic↗
PubMed1977

In vitro stimulation of human lymphocytes by Bordetella Pertussis.

Bordetella pertussis (B.p.) induces blast transformation of human lymphocytes; whole killed B.p. are more efficient than extracts obtained by sonication. Similar responses were obtained with each of the four strains used in the Danish pertussis vaccine. B.p. with low amounts of Protective Antigen and Histamine-Sensitizing Factor also induced lymphocyte transformation, but were less toxic to the lymphocytes at high concentrations. The supernatants of B.p. cultures were purified with respect to Lymphocytosis Promoting Factor; evidence is presented that these purified fractions possess T-lymphocyte mitogenic activity. Lymphocytes from all normal humans were stimulated by B.p., including cells from cord blood. Cells from childbearing women, obtained immediately after delivery, showed a general depression of lymphocyte transformation including the response to B.p. Children with whooping cough had a lower lymphocyte response to B.p. than healthy children. A highly significant correlation was observed between the responses to B.p. and to E. coli in the adults and newborn examined. It is concluded that the major part of the lymphocyte transformation induced by B.p. is non-specific.

Adult↗
PubMed1976

Loss of protective antigen, histamine-sensitising factor and envelope polypeptides in cultural variants of Bordetella pertussis.

Five Bordetella pertussis strains of phase I were grown in conventional casamino-acid medium and in media modified by adding high concentrations of MgSO4 or nicotinic acid. Cells grown in high-magnesium media (in the C-mode) had only about 4% of the protective antigen (PA) and 6% of the histamine-sensitising factor (HSF) of cells from the normal medium. Envelopes from C-mode organisms when examined by SDS-PAGE showed a loss of 28K and 30K polypeptide bands. Similar parallel losses of PA, HSF and 28K and 30K bands were found with cells from the high-nicotinic-acid medium. A medium with a high concentration of nicotinamide gave cells with normal amounts of PA, HSF and 28K and 30K bands. Growth in high concentrations of Na2SO4 caused partial losses of PA, HSF and 28K and 30K bands, while a high-succinate medium gave cells with somewhat diminished PA and HSF but without appreciable attenuation of the 28K and 30K bands. Because of the close correlation between the presence or absence of PA, HSF and 28K and 30K envelope polypeptides, it is suggested that the latter may represent or be closely associated with the components responsible for PA and HSF activities.

Animals↗
PubMed1976

Radiolabelling of Bordetella pertussis envelope proteins by the 125 I-lactoperoxidase method.

Bordetella pertussis strain number 18334 was grown in media which yielded cells with either a normal complement of surface antigens (X-model), or cells which were phenotypically altered (C-model). Neither X- nor C-mode bacteria incorporated more than traces of radioactivity when exposed to Na 125 I, lactoperoxidase and a source of H2O2 under conditions which gave substantial labelling of BSA and other soluble proteins. In contrast, envelope preparations were readily labelled. Analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that several polypeptides had incorporated 125 I but not in amounts proportional to their abundance in the envelopes. Envelopes from C-mode cells gave a labelling pattern similar to those of X-mode except in one region. Control experiments suggested that the failure of intact cells to become labelled may be due to bacterial inhibition of the reagents.

Autoradiography↗
PubMed1975

Cell-envelope proteins of Bordetella pertussis.

Cell-envelope polypeptides of eight phase-I and five phase-IV strains of Bordetella pertussis were compared by SDS-polyacrylamide gel electrophoresis. All phase-I strains gave a strikingly similar but complex pattern of protein bands, which did not appear to vary with known differences in heat-labile agglutinogens. Phase-IV strains gave the same pattern as phase-I strains, except that one band was missing and another was either much reduced or absent. Envelopes from phase-I strains grown in Hornibrook medium rich in Mg-2+ ions to produce "antigenically-modulated" C-mode cells gave a pattern of bands indistinguishable from phase-IV strains. A phase-IV strain grown in the high-Mg-2+ medium gave the same pattern of bands as when grown in unmodified Hornibrook medium. We suggest that the two polypeptide bands that show changes may be responsible for one or more of the immunological or physiopathological activities that are lost during phase variation and antigenic modulation in B. pertussis.

Allergens↗