Characterization of the Neurotoxin Produced by Isolates Associated with Avian Botulism

Abstract

Several varieties of birds are affected by type C botulism. We conducted neutralization tests of culture supernatants of isolates from cases of avian botulism. Whereas the toxin produced by isolates derived from mammalian botulism was neutralized only with type C antitoxin, the toxins of all isolates related to avian botulism were neutralized with both type C and D antitoxins. An analysis of nucleotide sequences with several strains revealed that the neurotoxin gene in the isolates from avian botulism comprises two thirds of the type C neurotoxin gene and one third of the type D neurotoxin gene. This indicates that the neurotoxin of avian isolates is a mosaic of type C and D neurotoxins. We prepared three sets of primers to differentiate the gene for the mosaic form from the conserved genes of type C and D neurotoxins. The results of polymerase chain reaction with these primers indicated that all avian botulism-related isolates and specimens possess the gene for the mosaic form of the neurotoxin. The toxins purified from avian and mammalian isolates exhibited the same degree of lethality in mice, but the former showed greater toxicity to chickens than the latter. These results indicate that the mosaic neurotoxin is probably a pathogenic agent causing some forms of avian botulism.

Management of Animal Botulism Outbreaks: From Clinical Suspicion to Practical Countermeasures to Prevent or Minimize Outbreaks

“…[10][11][12] Group IV, C. butyricum, and C. baratii produce type G, E, and F toxins, respectively. Some strains are also capable of producing 2 toxins simultaneously or may carry a second silent nonexpressed gene.…”

“…The mosaic toxin type C/D seems to be more lethal to chickens than type C toxin. 10 In addition, birds may harbor type D C. botulinum strains in their gut without showing symptoms. 22 Equine botulism is caused by type B, C, and A toxins.…”

Botulismo tipo C em perus em Minas Gerais, Brasil

“…Resistente à ação proteolítica, ela é absorvida pela mucosa intestinal e age nas placas neuromusculares impedindo a liberação do neurotransmissor acetilcolina, resultando em um quadro de paralisia flácida (ALMEIDA et al, 2000;TAKEDA et al, 2005).…”

Acute Type C Botulism with Fatal Consequences in a Holstein Breeding Establishment in Northern Italy

“…botulinum [21,22] and are extended in Europe. However, these types could not be detected in this study.…”