Characterization of the mammalian toxicity of the crystal polypeptides of Bacillus thuringiensis subsp. israelensis.
Solubilized crystal polypeptide preparations of Bacillus thuringiensis subsp. israelensis (BTI) were fractionated by immunoaffinity chromatography using a bound monoclonal antibody formed against the 28K crystal polypeptide. The 28K polypeptide was confirmed to be hemolytic and to possess low mosquitocidal activity against Aedes aegypti larvae. By comparison, the 28K polypeptide was more potent than the solubilized BTI crystals in male Swiss Webster mice, as the LD50 values were (p less than 0.05) 0.77 and 2.33 mg protein/kg body wt, respectively. Acute administration of the 28K polypeptide (mg/kg, ip) produced severe hypothermia and bradycardia in the mouse. No evidence for cooperativity between the 28K and other crystal polypeptides was observed. Preliminary histological examination of the mouse hearts exposed to the 28K polypeptide did not reveal any specific lesion, suggesting that the deficient cardiac performance might be a secondary physiological response. Gross pathological examination of mice as well as Sprague-Dawley rats acutely treated with equivalent doses of solubilized BTI crystal preparations revealed focal to segmental reddened and edematous areas within the small intestine. Histopathology indicated that the major lesion was in the jejunum. Contrary to expectations from in vitro hemolysis assays, cytolysis of mouse red and white blood cells was not detectable after in vivo exposure to the BTI solubilized proteins. The present results indicate that the 28K polypeptide is the mammalian toxic component of BTI crystals.
Mayes
M E
ME
U.S. Environmental Protection Agency, HERL, Research Triangle Park, North Carolina 27711.
Held
G A
GA
Lau
C
C
Seely
J C
JC
Roe
R M
RM
Dauterman
W C
WC
Kawanishi
C Y
CY
D000330:Aedes; D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D001772:Blood Cell Count; D001833:Body Temperature Regulation / Q000187:drug effects; D003460:Crystallization; D003720:Densitometry; D004562:Electrocardiography; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology; D007928:Lethal Dose 50; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D010455:Peptides / Q000032:analysis / Q000633:toxicity*; D051381:Rats; D012756:Sheep
D010455:Peptides