2005 Fiscal Year Final Research Report Summary
Clarification of the occurrence of avian botulism : the approach with molecular biological studies
| Project/Area Number |
16380207
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied veterinary science
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
KOZAKI Shunji Osaka Prefecture University, Graduate School of Life and Environmental Sciences, Professor, 生命環境科学研究科, 教授 (10109895)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Ryuji Osaka Prefecture University, Graduate School of Life and Environmental Sciences, Assistant Professor, 生命環境科学研究科, 講師 (10275282)
KOHDA Tomoko Osaka Prefecture University, Graduate School of Life and Environmental Sciences, Research Associate, 生命環境科学研究科, 助手 (80336809)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Clostridium botulinum / neurotoxin / botulism / avian species / mosaic form / receptor |
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| Research Abstract |
Several varieties of birds and domestic animals are affected by type C and D botulism. We conducted neutralization tests of culture supernatants of isolates from cases of avian botulism. The toxins of all isolates were neutralized with both type C and D antitoxins. An analysis of neurotoxin genes with several strains revealed that the gene in the isolates from avian botulism comprises two third of type C neurotoxin gene and one third of type D neurotoxin gene. This indicates that the neurotoxin of avian botulism is a mosaic of type C and D neurotoxins. We prepared three sets of primers to differentiate the gene for the mosaic form 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 greate
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r toxicity to chickens than the latter. The neurotoxin acts on nerve endings to block neurotransmitter release. Their potency is due to their enzymatic activity and selective high affinity binding to neurons. We prepared the recombinant carboxyl-terminal domain of the heavy chain (Hc) and then applied to survey the receptor for type C and D neurotoxins. When we examined the interaction of Hc/C and Hc/D with lipid extract from rat brain, Hc/C bound to gangliosides GD1b and DT1b, whereas Hc/D reacted with phosphatidylethanolamine but not gangliosides. Using cerebellar granule cells obtained from GM3 synthase knock-out mice, we found that type C neurotoxin did not a toxic effect but that type D neurotoxin still inhibited glutamate release to the same extent as in granule cells from wild type mice. These observations suggested that type C neurotoxin recognized GD1b and GT1b as functional receptors, while type D neurotoxin induced toxicity in a ganglioside-independent manner, possibly through to phosphatidylethanolamine. Less
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