https://mmbr.asm.org/content/mmbr/47/4/510.full.pdf

New knowledge on pathogenesis of bacterial enteric infections as applied to vaccine development.

The drastic intestinal secretion of fluid and electrolytes that is characteristic of cholera is the result of reasonably well understood cellular and biochemical actions of the toxin secreted by Vibrio cholerae. Based on this understanding it is possible to devise new techniques for the treatment and prophylaxis of cholera to complement those based on fluid replacement therapy and sanitation.

/pdf/actions-of-cholera-toxin-and-the-prevention-and-treatment-of-3cuaftxawv.pdf

Actions of cholera toxin and the prevention and treatment of cholera

We performed a prospective study to examine whether the IgA antibodies against cholera that are present in breast milk protect breast-fed infants and children against colonization with Vibrio cholerae 01 and disease. Among families of patients with cholera, we collected breast milk from mothers who had not had diarrhea in the previous week and monitored them and their breast-fed children for cholera colonization and diarrhea for 10 days. Breast milk was assayed for IgA antibodies to cholera toxin and lipopolysaccharide. Ninety-three mother–child pairs were studied; 30 infants became colonized with V. cholerae 01 and disease developed in 19. There were no differences between the antibody levels in milk fed to children who became colonized and in milk fed to children who did not. However, among the children who became colonized, those who had diarrhea drank breast milk containing significantly lower levels of both kinds of cholera antibodies than were present in the milk consumed by children who ha...

https://www.nejm.org/doi/pdf/10.1056/NEJM198306093082304

Protection against Cholera in Breast-Fed Children by Antibodies in Breast Milk

Field trial of oral cholera vaccines in Bangladesh

The protective efficacy of oral B subunit killed whole-cell (BS-WC) and killed whole-cell (WC) cholera vaccines was assessed in 63 498 Bangladeshi children aged 2-15 years and women aged over 15 years. Each received three doses of BS-WC, WC, or placebo in a randomised, double-blinded fashion. Surveillance for cases seeking medical care up to six months after the third dose revealed 26 cases of confirmed cholera in the placebo group, 4 cases in the BS-WC group (protective efficacy 85%; p less than 0.0001), and 11 cases in the WC group (protective efficacy 58%; p less than 0.01). For each vaccine protective efficacy was consistent in different age-groups (2-10 years versus greater than 10 years) and for different severities of cholera.

Subcutaneous immunization of rabbits with a combination of Vibrio cholerae lipopolysaccharide (LPS) and enterotoxin induced a more than 100-fold-higher degree of protection against intestinal challenge with live cholera vibrios than did vaccination with either of the two antigens alone. Such a synergistic effect was also obtained by immunization with a combination of LPS and choleragenoid. The immunization with LPS and toxin (or toxoid) in combination did not enhance the reistance to toxin challenge above that induced by the toxin component alone. This, together with data from titrations of anti-LPS and antitoxin antibodies in serum and in intestinal washings, contradicts enhanced immune responses due to adjuvant action of the two antigens as the explanation for the synergistic effect of the combined vaccines. A more likely explanation would be that the antibacterial and antitoxic immune responses, without being increased in themselves, function synergistically by interfering with two separate events in cholera pathogensis.

J Holmgren

Papers

Synergistic protective effect in rabbits of immunization with Vibrio cholerae lipopolysaccharide and toxin/toxoid.