The immunogenicity in humans of a botulinum type F vaccine

A purified monovalent botulinum type F toxoid vaccine was administered to 35 healthy adult volunteers in a phase I clinical trial. Serum samples from the vaccinated volunteers were evaluated for an antibody response at various time intervals over 1 year by mouse bioassay and ELISA. The antibody response was measured for varying doses of vaccine (2, 5, or 10 microg), and after single or multiple (two or three doses @ 10 microg) vaccinations. Six out of 15 (40%) individuals developed antibody titers after receiving a single dose. After two and three vaccinations, there was a 90% (18/20) and 100% (10/10) seroconversion rate, respectively. Eight months after initial injection, 57 and 63% of individuals were antibody positive following two or three vaccinations, respectively. Single vaccinations, at any of the tested dosages, elicited lower, if any, antibody response than did multiple vaccinations. After the third vaccination, ELISA titers positively correlated with mouse neutralization bioassay titers (r(2)=0.86).