A novel function of botulinum toxin-associated proteins: HA proteins disrupt intestinal epithelial barrier to increase toxin absorption.

Food-borne botulinum neurotoxin (BoNT) in the gastrointestinal lumen must cross an epithelial barrier to reach peripheral nerves to mediate its toxicity. The detailed mechanism by which BoNT traverses this barrier remains unclear. We found that hemagglutinin (HA) proteins of type B BoNT complex play an important role in the intestinal absorption of BoNT, disrupting the paracellular barrier of intestinal epithelium, which facilitates transepithelial delivery of BoNT both in vitro and in vivo (Matsumura, T., et al., 2008. Cell. Microbiol. 10, 355-364). We also found that type A HA proteins have a similar disrupting activity with a greater potency than type B HA proteins in the human intestinal epithelial cell lines Caco-2 and T84. In contrast, type C HA proteins in the toxin complex (up to 300 nM) have no detectable effect on the paracellular barrier in these human cell lines. These results may indicate that types A and B HA contribute to develop the food-borne human botulism by facilitating the intestinal transepithelial delivery of BoNTs.

Comparative studies of the persistence of animal mycoplasmas under different environmental conditions.

A comparison of the persistence of mycoplasmas in animals was carried out. When inoculated into liquid media, strains of Mycoplasma bovis, M. arginini, Acholeplasma laidlawii, and A. axanthum persisted for 59-185 days post-inoculation. The survival periods were not significantly influenced by temperature (4, 30, 37 degrees C, and room temperature). The survival periods for M. bovigenitalium, M. gallisepticum, M. bovirhinis, and M. gateae ranged from <7 to 185 days depending on medium components and temperature. Further, it was determined that strains of M. bovigenitalium, M. bovis, M. bovirhinis, M. arginini, and A. laidlawii persisted in a dry paper disc for at most 28, 126, 154, 56 and over >168 days at 4 degrees C, respectively. At 4 degrees C, strains of M. gallisepticum, M. columborale, M. edwardii, M. felis, and M. gateae survived for at most 28, 21, 42, 28, 28 and 70 days, respectively. At 30 degrees C, strains of M. bovis, M. bovirhinis, M. arginini, A. laidlawii, and M. gallisepticum persisted for at most 28, 84, 56, >168 and 14 days, respectively, but strains of M. gallisepticum, M. columborale, M. edwardii, M. felis, M. gateae, and U. diversum did not survive for more than 14 days. In an outdoor environment, strains of M. bovirhinis and A. laidlawii survived for at most 28 and 14 days, respectively. Finally, it was found that 14 isolates of M. gallisepticum persisted for periods similar to those of the reference strains. The results under dry conditions at a variety of temperatures presented contribute to understanding the epizootiology of mycoplasmal infections in the field.