IgG and IgA subclass distribution of antitoxin antibody responses after oral cholera vaccination or cholera disease

The immunoglobulin subclass distribution of cholera antitoxin antibody responses in serum was studied in Swedish volunteers after different routes of immunization with a cholera B subunit-whole cell vaccine (B + WCV) and in Bangladeshi patients convalescing from cholera disease. Both oral and parenteral immunization induced antitoxin antibodies of all the different IgG subclasses (IgG1, IgG2, IgG3 and IgG4) whilst the IgA antibodies were restricted to the IgA1 subclass. A single oral dose of B + WCV induced proportionally higher levels of IgG4 antitoxin in previously cholera-immunized volunteers than in a matched group who had not been cholera-vaccinated before, suggesting that repeated immunization preferentially stimulate formation of IgG4 antibodies. The IgG and IgA subclass distribution of antitoxin antibodies in orally vaccinated Swedes closely resembled that in Bangladeshi cholera patients.