MODIFIED TOXIN-BINDING INHIBITION (TOBI) TEST FOR QUANTIFICATION OF EPSILON ANTITOXIN IN SERUM FROM IMMUNIZED SHEEP

Macedo Sobrinho, ElianeChristina Almeida, AnnaOtacílio Santos, HerculesSander Rodrigues Cangussu, AlexColen, FernandoViana Brandi, IgorSoger Sari, RogerQuintilio, Wagner

This study evaluated the use of the ToBI test as a substitute for the in vivo technique of the mouse serum neutralization test to manage quality control of vaccines against clostridiosis. Serum samples with known concentrations of anti-epsilon antibodies were obtained from 3 sheep immunized with vaccine against C. perfringens type D epsilon toxoid. The main results obtained indicate correlation coefficients above 97%, corroborating literature data. The inter and intraplate coefficients of variation were low (less than 1.3%). In conclusion, the in vitro ToBI test is suitable to evaluate the potency of clostridial vaccines. However, the ToBI test must be first validated before it can replace the in vivo serum neutralization methodology used in mice. Keywords: Clostridiosis, in vitro assay, potency testing.