Use of mutants in the elucidation of virulence of Streptococcus mutans.
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Biomedical subjects
Publications and source records attributed to R R Arnold.
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Ingestion of capsules which contained killed Streptococcus mutans by four healthy human subjects led to the appearance of specific antibodies in external secretions. Salivary and lacrymal antibodies were detected within 1 wk of ingestion and continued to increase throughout a 14-day immunization period, with a gradual decline during the 2 ensuing months. A second period of immunization resulted in a pronounced increase of specific antibody levels which occurred earlier than in the primary immunization period and reached peak levels by day 10. No change was detected in serum antibody levels throughout either immunization period. The antibody activity in all secretions was associated with the immunoglobulin A class, as determined by immunochemical analyses. These data indicate that ingestion of bacterial antigens selectively stimulates the immune response in secretions.
Streptococcus mutans and Vibrio cholerae, but not Escherichia coli, were killed by incubation with purified human apolactoferrin. Concentrations of lactoferrin below that necessary for total inhibition resulted in a marked reduction in viable colony-forming units. This bactericidal effect was contingent upon the metal-chelating properties of the lactoferrin molecule.
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This study was undertaken in order to correlate the immune status of persons with various types of immune dysfunctions with the incidence of dental caries. Preliminary data on caries experience and the microbial composition of plaque in these individuals are presented. The findings suggest that persons with immunoglobulin dysfunctions have a greater susceptibility to dental caries and have a greater frequency of harboring S mutans than do normal persons.
Ingestion of killed cells of a highly cariogenic strain of Streptococcus mutans induced specific antibodies in both saliva and milk but not in serum of gnotobiotic rats. These antibodies were associated with the immunoglobulin A class. When infected with Streptococcus mutans, orally immunized animals developed significantly fewer carious lesions than nonimmunized infected controls.
Human colostrum, parotid saliva, and serum were assayed for the presence of naturally occurring antibodies to five serotypes of Streptococcus mutans. Appreciable levels of agglutinins to strains AHT, BHT, 10449, 6715, and LM-7 (groups a leads to e, respectively) were detected in normal colostrum and saliva, whereas relatively low levels were found in serum. No agglutinins could be detected in the colostrum or saliva of immunodeficient patients. Molecular sieve chromatography of the colostrum on Sephadex G-200 revealed agglutinin activity in the secretory immunoglobulin A (s-IgA)-rich fraction only. Titration of purified colostral s-IgA confirmed the IgA nature of this agglutinating activity. Indirect immunofluorescence tests with anti-s-IgA, -IgG, and -IgM revealed S. mutans specificity only in the s-IgA class. The presence of s-IgA antibodies to indigenous oral microorganisms in colostrum, as well as in saliva, suggests that antigenic stimulation occurs at a site remote from the oral mucosa.
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