Potential of Klebsiella pneumoniae cytotoxin toxoid as vaccine against klebsiellosis in rabbits and mice

The protective efficacy of toxoids prepared from crude cytotoxin (polymyxin -B extract, PBE) and purified Klebsiella cytotoxins (KCTs) was studied in r abbits and mice. The toxoids of KCT-I and PBE were found to be protective a gainst homologous as well as heterologous Klebsiella challenges, while toxo ids of KCT-II and KCT-III afforded protection in mice against homologous Kl ebsiella infections. KCT-I and PBE toxoids also induced good humoral anti-K lebsiella response in rabbits with ELISA titres ranging from 20480 to 81480 . Immunized female rabbits passed protective anti-Klebsiella immunoglobulin s to their of springs through colostra. Baby rabbits fed on colostrum of im munized rabbits withstood lethal Klebsiella infection up to I month of age, but not on the 50th day. Baby rabbits having an anti-Klebsiella IgG titre greater than or equal to 1280 were fully protected against lethal dose of K lebsiella. The study revealed a significant protective efficacy of KCT-I an d PBE toxoids against klebsiellosis in mice and rabbits. (C) 2001 Elsevier Science Ltd. All rights reserved.