Mediaselektion

Freter, Hermann

doi:10.1007/978-3-322-88037-6

Cited by 33 publications

(3 citation statements)

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“…If, as we suspect, there is an antitoxic component due to stimulation of local immune mechanisms by choleragenoid elaborated by the mutant, then it is niot unlikely that the mutant, used as a living enteric vaccine, may offer some degree of protection against those enterotoxic enteropathies-far more important worldwide than cholera as causes of morbidity and mortality-which depend on enterotoxins that are immunologically related to the cholera enterotoxin through the B (choleragenoid) region. That there is also a specific antivibrio component may be inferred from the effects noted on colonization in immunized animals, which resemble those reported earlier by Freter (33). The reported (34) synergy between the antibacterial and antitoxic components of cholera immunity, the fact that the disease itself is an effective immunizing process, and the observation that hypotoxinogenic M13 induced protection in volunteers which was not quite as solid as that of the disease itself, all suggest that Texas Star-SR may be expected to harmlessly simulate infection with virulent vibrios and induce substantial immunity against cholera.…”

Section: Discussionsupporting

confidence: 87%

Selection and characteristics of a Vibrio cholerae mutant lacking the A (ADP-ribosylating) portion of the cholera enterotoxin.

Honda¹,

Finkelstein²

1979

Proc. Natl. Acad. Sci. U.S.A.

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After mutagenesis with nitrosoguanidine and selection by immuno-halo techniques, an avirulent mutant, designated Texas Star-SR, which produces no detectable A (active; ADP-ribosylating) region of the cholera enterotoxin (choleragen) but produces the B region (choleragenoid) in amounts similar to the hypertoxinogenic wild-type parent Vibrio cholerae (biotype El Tor serotype Ogawa), has been isolated. The mutant retains the colonizing ability, motility, prototrophy, and serologic characteristics of the parent. In relevant intestinal experimental models, it has been shown to be avirulent and to induce protection against challenge with virulent cholera vibrios. The mutant appears to be suitable for further evaluation in volunteers as a candidate living enteric vaccine against cholera and related enterotoxic enteropathies. Cholera is the prototype of an increasing number of newly recognized diarrheal diseases, enterotoxic enteropathies, which depend on soluble enterotoxins, some of which are related to the cholera enterotoxin (choleragen), both immunologically and by mode of action (1). Perhaps because of its intestinal locus, conventional cholera vaccines composed of killed bacteria, administered parenterally, are relatively ineffective in preventing cholera (2). However, the disease itself is an immunizing process (3). Further, a perorally administered hypotoxinogenic Vibrio cholerae mutant, M13 (4), was found to be avirulent for human beings and to induce substantial immunity against subsequent challenge with virulent cholera vibrios (5, 6). Because of its limited production of toxin antigen, M13 would offer little, if any, protection against other enterotoxic enteropathies. Because it also appeared to be unstable (5, 6), further evaluation of M13 as a vaccine was contra-indicated.Choleragen is a polymeric protein consisting of noncovalently associated subunits (7), of which the A region is responsible for activation of adenylate cyclase and the B region (choleragenoid), which has been shown to be highly immunogenic, is responsible for binding of the holotoxin to host cell membrane receptors, thereby facilitating entry of the A region (8-11). Thus an A-B+ V. cholerae mutant could be predicted to be avirulent and capable of stimulating local immunity against cholera and the immunologically related enterotoxins that share B-related antigens. The potential value of such a mutant was postulated earlier (12). The isolation and characterization of such an A-B+ mutant, which appears to be stable, is described in this report. METHODSV. cholerae Strains. Two hypertoxinogenic strains of V. cholerae were used. The first, V. cholerae 569B, a classical vibrio of the Inaba serotype, has been widely used by us and by others for production of choleragen and in genetic studies (4,(13)(14)(15)(16). The other was 3083, an El Tor biotype Ogawa serotype, isolated by one of us (R.A.F.) from a patient in Vietnam in 1964 (17), which has been shown to be highly adherent in infant rabbits (18). All strains and mutants were maintai...

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Section: Discussionsupporting

confidence: 87%

Selection and characteristics of a Vibrio cholerae mutant lacking the A (ADP-ribosylating) portion of the cholera enterotoxin.

Honda¹,

Finkelstein²

1979

Proc. Natl. Acad. Sci. U.S.A.

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“…Recent elegant research on forces influencing transfer of genetic information among E. coli strains in the gastrointestinal tract [44] should be extended to strictly anaerobic members of the microflora, and particularly to such bacteria in epithelial communities.…”

Section: Perspectives For Research In the Futurementioning

confidence: 99%

Microorganisms associated with epithelial surfaces and stability of the indigenous gastrointestinal microflora

Savage

1987

Nahrung

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Indigenous microorganisms of many genera and species associate with mucosal epithelia in the gastrointestinal tracts of animals and humans. These mechanisms may involve a high degree of specificity for host and surface habitat. They may include a capacity of the microorganisms to adhere to the membranes of substratum epithelial cells, to colonize and utilize as a source of nutrients the mucus overlying epithelial cells, and to be motile and attracted into the mucous layer by chemotaxis. The microbes must be able as well to thrive in the nutritional and environmental conditions prevailing on the epithelial surfaces. Microbial communities associated with epithelial surfaces are critical for maintaining a microflora in areas of the tract (i.e., stomach, small intestine) where the lumenal content moves at a rate exceeding the maximum rates at which indigenous microorganisms can multiply. Such communities even may be important in areas (i.e., the cecum and colon) where the content moves at rates below those at which the microbes can multiply. In such areas, microorganisms colonizing mucus on the epithelium and in the crypts of Lieberkuhn may provide a stable inoculum for the lumenal content which may be altered in composition in times of dietary change. Microorganisms associated with gastric and intestinal surfaces undoubtedly serve in a major way to stabilize the composition of the indigenous gastrointestinal microflora. At the molecular level, however, little is known about the mechanisms stabilizing the composition or the biochemical and genetic activities of the microflora. Such mechanisms are important subjects for research in the future.

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“…Several synergistic mechanisms work in tandem to cause antagonism of E. coli in these microenvironments. FRETER (13) reported that in competition for substrate from diet, inhibitory fatty acids and low pH contributed to conditions to reduce the E. coli population in vitro in anaerobic continuous flow-cultures. BERG and OWENS (14) concluded that antagonism of indigenous E. coli strains by anaerobic intestinal bacteria is a consequence of the sequential development of the normal bacterial flora in the mouse intestine.…”

Section: Discussionmentioning

confidence: 99%

In vitro antagonism of Escherichia coli by piglet small intestinal bacteria isolated by selective enrichment in media containing sow colostrum, piglet feed or brain heart infusion.

Aimutis

Kornegay

Eigel

1985

J. Gen. Appl. Microbiol.

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Mediaselektion

Cited by 33 publications

References 0 publications

Selection and characteristics of a Vibrio cholerae mutant lacking the A (ADP-ribosylating) portion of the cholera enterotoxin.

Selection and characteristics of a Vibrio cholerae mutant lacking the A (ADP-ribosylating) portion of the cholera enterotoxin.

Microorganisms associated with epithelial surfaces and stability of the indigenous gastrointestinal microflora

In vitro antagonism of Escherichia coli by piglet small intestinal bacteria isolated by selective enrichment in media containing sow colostrum, piglet feed or brain heart infusion.

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