Titration of Cholera Antitoxin Levels by Passive Hemagglutination Tests Using Fresh and Formalinized Sheep Erythrocytes

Hochstein, H D; Feeley, John C.; Richardson, S H

doi:10.3181/00379727-133-34421

Cited by 21 publications

(12 citation statements)

References 3 publications

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“…Fresh SRBC were sensitized by the method of Hochstein et al (1970). Briefly, SRBC were washed three times in cold saline (0.850/,) and the cells were suspended to a final concentration of 5% (v/v) in pure toxin (15 pg per ml saline) or A or B subunit toxin (each 25 pg per ml saline; all purchased from Calbiochem, USA).…”

Section: Abbreciationsmentioning

confidence: 99%

“…Antitoxin levels were determined by a passive haemagglutination (HA) test with toxin-sensitized SRBC (Hochstein et al, 1970). Briefly, 0.3 ml of serial dilutions of sera were mixed with 0.3 ml sensitized SRBC in HA plates and incubated for 2 h at 37 "C followed by overnight incubation at 4 "C. Titres were recorded as the highest serum dilution showing positive HA.…”

Section: Abbreciationsmentioning

confidence: 99%

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Regulation of Toxin Biosynthesis by Plasmids in Vibrio cholerae

Khan¹,

Srivastava²,

Sinha³

et al. 1985

Microbiology

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2653Vibrio cholerae strain 569B Inaba harbouring P plasmid produced less toxin than the parent strain. To examine the effect of plasmid loss on toxin production, temperature-sensitive (ts) mutants of P, unable to replicate at 42 "C, were isolated. One ts plasmid was unstable at 42 "C and its loss yielded a cured strain that resumed a normal level of toxin biosynthesis characteristic of the plasmid-free parent strain. Toxin production was again suppressed in the cured strain after reacquisition of P plasmid. This suggested a role for plasmid-borne genes in the regulation of toxin biosynthesis. A mutant of strain 569B Inaba that produced mutant toxin was isolated by transfer of P and V plasmids. The mutant toxin was similar to choleragenoid because it did not give rise to symptoms of cholera but induced antitoxin immunity in rabbits.

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Section: Abbreciationsmentioning

confidence: 99%

Section: Abbreciationsmentioning

confidence: 99%

Regulation of Toxin Biosynthesis by Plasmids in Vibrio cholerae

Khan¹,

Srivastava²,

Sinha³

et al. 1985

Microbiology

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“…Both proteins also interact with natural membranes such as those at the surface of intestinal villi (Peterson, LoSpalluto, and Finkelstein, J. Infect. Dis., in press) and untanned erythrocytes (6,9).…”

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confidence: 99%

Properties of the Cholera Exo-Enterotoxin: Effects of Dispersing Agents and Reducing Agents in Gel Filtration and Electrophoresis

1972

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Initial studies, by using polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS), led to the attractive hypothesis that the cholera exo-enterotoxin (choleragen) consisted of two noncovalently linked peptides of 56,000 and 28,000 molecular weight. The spontaneous toxoid (choleragenoid) appeared to be identical with the 56,000 molecular weight piece. The results appeared to be very similar to those obtained recently with diphtheria toxin. However, they did not agree with earlier studies which indicated that both the toxin and the toxoid consisted of subunits of approximately 14,000 molecular weight. More extensive investigation, by using gel filtration with 3H-labeled toxin, ultracentrifugation, and immunologic studies, failed to support the observations of SDSgel electrophoresis, suggesting the existence of a 28,000 molecular weight fragment which is unique to the toxin. The results were more compatible with our earlier observations regarding subunit composition. It is concluded that these proteins are relatively resistant to dissociation by SDS and need to be unfolded by prior treatment for more complete dissociation into subunits. Indirect evidence suggests that the 28,000 fragment may be a dimer, or larger aggregate, of a smaller subunit which can be integrated in the formation of choleragenoid. It is also evident that caution should be exercised in the interpretation of results, however pleasing, obtained only by SDS-gel electrophoresis. 934 Vol. 6,No. 6 Printed in U.S.A.

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“…Peterson, LoSpalluto, and Finkelstein (29) found that after exposing intestinal mucosa to choleragen, the toxin could be localized to the intestinal mucosa with immunohistochemical and autoradiographic techniques. Cholera toxin can also bind to intact sheep erythrocytes, since toxintreated cells agglutinate on exposure to cholera toxinspecific antiserum (30). We have also found that ['I]-choleragen binds to human erythrocytes and to turkey erythrocytes; however, adding 10-7 M nonradioactive choleragen reduced binding by only 20%, indicating that the apparent affinity with which choleragen binds to these cells is lower than that observed in rat thymocytes, or that the binding sites are so abundant that they cannot be "saturated" at 10-7 M choleragen.…”

Section: Discussionmentioning

confidence: 99%