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Title: The immunogenicity of staphylococcal delta-haemolysin
Author: Stearne, Lorna E. T.
ISNI:       0000 0001 3478 6329
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1979
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Native delta-haemolysin of Staphylococcus aureus was poorly immunogenic in the mouse, inducing low anti-delta-haemolysin antibody titres in only 50% of immunised animals. Treatment of delta-haemolysin with formaldehyde at pH 5 or pH 7.5 caused a rapid loss of haemolytic activity and, on treatment for 7 days at pH 5, gave a product of higher immunogenicity than the native material. Treatment of delta-haemolysin with formaldehyde at pH 9.5 for 7 days reduced the haemolytic activity by 97% that failed to enhance the immunogenicity. Antisera to formaldehyde-treated delta-haemolysin contained antibodies directed against antigenic sites not present on the native molecule. Formaldehyde-treated delta-haemolysin had an increased electrophoretic mobility and a reduced isoelectric point but there was no evidence of polymerisation. The enhanced immunogenicity may be due to a reduced affinity for phospholipids, resistance to enzymic digestion, increased rigidity and/or the masking of a suppressor determinant on the molecule. Treatment of delta-haemolysin with glutaraldehyde under acid, neutral or alkaline conditions produced a rapid loss of haemolytic and immunogenic activities. High doses of delta-haemolysin (62.5-1000 mug) gave enhanced vascular permeability (EVP) when injected intradermally in the rabbit. The response was obtained at a critical time of 1 h between injection of sample intradermally and of Pontamine Sky Blue Dye intravenously. The EVP activity was resistant to heating at 100°C. Treatment of the haemolysin with lecithin or formaldehyde reduced, but did not eliminate, this activity. Tryptic digestion studies indicated that the EVP activity was associated with fragments which lacked both haemolytic and antigenic activities, and suggested that the various biological activities of the molecule may not be mediated by a common site or mechanism. Several strains of S. aureus were screened for haemolysin production. The majority of human and animal strains produced high titres of α- and δ-haemolysins but little or no β3-haemolysin. The antigenic reactivity of the crude culture supernates with rabbit anti-δ-haemolysin antisera indicated that all animal strains and all but one of the human strains produced a haemolysin which was antigenically identical to purified δ-haemolysin from strain NCTC 10345. The human strain, LS26, produced a δ-haemolysin which precipitated with antibodies against purified δ-haemolysin and which carried specificities directed against determinants not exposed on the native molecule. These results suggested that "hidden" antigenic determinants may be "exposed" during immunisation with δ-haemolysin which induce specific antibody formation. Production of δ-haemolysin by strain LS26 may expose these "hidden" antigenic determinants which would therefore be free to precipitate with the specific antibody. Several of the crude delta-haemolysin preparations had very similar isoelectric points to that of purified δ-haemolysin. Only two out of seven crude preparations induced the production of anti-δ-haemolysin antibodies.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available