INTRANASAL VACCINATION OF HUMANS WITH RECOMBINANT CHOLERA-TOXIN-B SUBUNIT INDUCES SYSTEMIC AND LOCAL ANTIBODY-RESPONSES IN THE UPPER RESPIRATORY-TRACT AND THE VAGINA

Forty-five volunteers were vaccinated twice intranasally with 10, 100, or 1,000 mu g of cholera toxin B subunit (CTB). Blood and nasal and v aginal secretions were collected before and 1 week after the second va ccination from ail volunteers, and the specific and tc,tal immunoglobu lin A (IgA) and IgG titers were determined by enzyme-linked immunosorb ent assay. Samples were also taken 6 months (n = 16) and 1 year (n = 1 4) after the vaccination. The 10- and 100-mu g doses were well tolerat ed by the volunteers, but the 1,000-mu g dose induced increased secret ions from the nose and repetitive sneezings for several hours. The CTB -specific serum IgA and IgG increased 21- and 7-fold, respectively, 1 week after vaccination with the medium dose and increased 61- and 37-f old, respectively, after the high dose. In nasal secretions the specif ic IgA and Ige increased 2- and 6-fold after the medium dose and 2- an d 20-fold after the high dose, respectively. In vaginal secretions the specific IgA and IgG increased 3 and 5-fold after the medium dose and 56- and 74-fold after the high dose, respectively. The lowest dose di d not induce ang significant antibody titer increases in serum or in s ecretions, The specific IgA and IgG levels in secretions were still el evated after 6 months but were decreasing 1 year after the vaccination . These results show that intranasal vaccination of humans with CTB in duces strong systemic and mucosal antibody responses and suggest that CTB mag be used as a carrier for antigens that induce protective immun ity against systemic as well as respiratory and genital infections.