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Phage conversion to hemagglutinin production in Clostridium botulinum types C and D.

Five toxigenic strains of Clostridium botulinum types C and D were incubated at 37 degrees C for 7 days in 15 ml of the following media: LYG medium, cooked-meat medium, egg meat medium, and N-Z-amine medium. The supernatants of these cultures were tested for hemagglutinin production with 1% erythrocytes obtained from mice, guinea pigs, chickens, sheep, monkeys, and humans. Four toxigenic strains produced hemagglutinin. The highest hemagglutinin titer was obtained with a combination of human erythrocytes and cultures incubated in LYG medium. When the same experiment was carried out with many nontoxigenic strains, hemagglutination was observed in only one strain, C-N71. Strains producing hemagglutinin also produced phages. The phages obtained from toxin- and hemagglutinin-producing strains converted nontoxigenic indicator strains to produce both toxin and hemagglutinin. The phage obtained from a toxin-positive hemagglutinin-negative strain could only induce cultures to produce toxin, and the phage from a toxin-negative hemagglutinin-positive strain could only induce production of hemagglutinin. These studies suggest that the production of hemagglutinin by C. botulinum types C and D is governed by bacteriophages and that hemagglutinin production can be transmitted separately or concomitantly with toxin production.

Bacteriophages↗

Rapid detection and quantitative estimation of type A botulinum toxin by electroimmunodiffusion.

An experimental system is described for the detection and quantitative estimation of type A botulinum toxin by electroimmunodiffusion. The method is shown to be rapid, specific, and quantitative. As little as 14 mouse LD(50) per 0.1 ml of type A toxin was detected within 2 hr. When applied to experimentally contaminated foods such as canned tuna, pumpkin, spinach, green beans, and sausage, the technique detected botulinum toxin rapidly and identified it as to type and quantity. A specific rabbit type A antitoxin was produced for this in vitro system since the equine antitoxin (Center for Disease Control) tested in this experiment was found to be unsuitable.

Animals↗

Comparison of the reactivities and immunogenicities of procholeragenoid and the B subunit of cholera toxin in Thai volunteers.

Procholeragenoid, a stable high-molecular-weight aggregate of cholera toxin derived by heat treatment, was evaluated for reactivity and immunogenicity in adult Thai volunteers. Since procholeragenoid is known to retain some residual activity of cholera toxin, increasing amounts were ingested until diarrhea occurred; 250 micrograms induced diarrhea, but 100 micrograms did not. Procholeragenoid and cholera toxin B subunit, both in 100-micrograms amounts, were then compared for systemic and intestinal antitoxin responses. When three peroral doses were given, these immunogens gave comparable responses. The secretory immunoglobulin A antitoxin responses to three doses of 100 micrograms of B subunit did not differ significantly from responses found in previous studies of Thai adults given 1 or 5 mg of B subunit, but serum antitoxin responses were less after 1 or 2 doses of 100 micrograms than after doses of 1 or 5 mg. Serum antitoxin levels were similar after 3 doses of B subunit. Procholeragenoid in the maximum safe dose of 100 micrograms does not offer any immunologic advantage over B subunit, although it may be less expensive and easier to produce. However, these studies suggest that higher amounts of B subunit are more immunogenic and may be preferable, if found to be sufficiently cost effective, when added to oral killed whole Vibrio cholerae vaccines.

Adult↗