The antibody response to the Clostridium novyi type B alfa toxin component of 13 commercial vaccines (T1 to T13) and a standard toxoid was evaluated by the serum neutralization test with rabbit and cattle sera and by direct challenge of vaccinated guinea pig. T1 and T10 induced titles of C. novyi type B alfa antitoxin in rabbits, superior to the recommended minimum title of 3.5 IU/ml, namely of 8 and 12 IU/ml, respectively. T2 and T5 induced titles of 2 and 3 IU/ml, respectively. These, plus T1 and T10, were also the only vaccines which produced detectable antitoxin in bovine sera. T1, T2, T5 and T10, plus T11, were able to protect all the vaccinated guinea pigs at the challenge. Most of C. novyi type B vaccines in Brazil was unable to induce the minimum antibody response recommended for approval of the product.
vaccine; toxin; Clostridium novyi type B; infectious necrotic hepatitis; clostridiosis