Insecticidal toxins from the parasitic wasp bracon hebeter

Details Insecticidal toxins from the parasitic wasp bracon hebeter Insecticidal toxins from the parasitic wasp bracon hebeter

1996-05-31

2001-06-26

Carlson, Karen Cochrane (Department: 1653)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Peptide containing doai

C514S002600, C530S350000, C530S858000, C536S023100, C424S405000, C424S538000, C435S069100

Reexamination Certificate

active

06251862

ABSTRACT:

BACKGROUND OF THE INVENTION
In recent years, venoms of insects and arachnids, in particular spiders and scorpions, have been investigated as a potential source of biologically active substances for use in various fields such as medicine and agriculture. Examples of such work include:
EP Patent Application, Publ. No. 208 523 A2: Glutamate Antagonists Isolated from New World Spiders Argiope trifasciata and Araneus gemma.
EP Patent Application, Publ No. 156 540: Glutamate Receptor Inhibitor obtained from Nephila clavata.
Grishin et al., 1986. “Ion Channel Blocker from the Venom of Argiope lobata”
Biorg. Khim.
12(8):1121-1124.
Usherwood et al., 1984. “Glutamate Channel Blockade by Venoms of Argiope trifasciata and Araneus gemma”
J. Physiol. Paris
79:241-245.
Aramaki et al. 1986. “Glutamate Potential Suppressor from Nephila clavata and Nephila maculate”
Proc. Japan Acad.
62, Ser B:359-362.
Usherwood et al., 1985. “Antagonism of Glutamate Receptor Channel Complexes by Spider Venom Polypeptides”
Neurotoxicology
6(2):239-250.
Adams et al. 1986. “Synaptic Toxins from Agelenopsis aptera”
Insect Neurophysiology
, Borkovec et al., Eds. Humana Press, Clifton, N.J. 397-408.
Bracon hebetor (also known as Habrobracon hebetor and Microbracon hebetor) is a small (ca. 2 mm, less than 1 mg) ectoparasitic wasp, which has a venom that is paralytic to lepidopterans (Drenth, D. 1974, Toxicon 12:189-192). The quest to identify toxins in B. hebetor venom has continued for several years (see, e.g. Visser et al, 1976, Toxicon 14:357-307; Visser et al, 1983, Comp. Biochem. Physiol. 75B:523-530; and Spanjer et al, 1977, Toxicon 15:413-421). Most attempts have been frustrated by the lability of the toxins. Two protein toxins (mol. wt. 44 and 57 kda) have been purified and partially characterized, but they represent only 2% of the original insecticidal activity (Visser et al, supra, 1983). More recently, Slavnova et al, 1987
Doklady Akademii Nauk USSR
297:492-494 reports isolation of a toxin having a mass of 18 kda.
DESCRIPTION OF THE INVENTION
It has now been found that certain polypeptides, when isolated from the venom of the wasp Bracon hebetor are toxic, i.e. paralytic and/or lethal to insects, particularly of the order Lepidoptera, at surprisingly low concentrations.
The present invention, therefore, concerns toxins free from associated wasp polypeptides which demonstrate toxicity towards insects. These polypeptides may be isolated from, or be constructed to show substantial sequence homology to polypeptides isolated from the venom of Bracon hebetor. Preferred peptides are rather large, and may be characterized in having a molecular weight which exceeds 70,000 da. Five preferred polypeptides were isolated and were designated Brh-I to Brh-V.
As used throughout the specification and claims, the following definitions are intended:
Associated wasp polypeptides—polypeptides naturally occurring in the venom of B. hebetor which are toxic to insects.
Homologous polypeptide—a polypeptide which is identical to one of the native toxins of this invention, or substantially homologous (at least 80%) with respect to the amino acid sequence, such that it demonstrates substantially the same insect toxicity in in vivo assays as a native toxin.
Homologous nucleotide sequence—a sequence which will hybridize to the reference sequence under stringent hybridization conditions.
Stringent hybridization conditions—those in which hybridization is effected in a standard manner at 65° C. in 4X buffered saline (a.k.a. SSPE buffer) followed by merely washing at 52° C. in 0.2 X SSPE, which will not affect true hybrids which have formed.


REFERENCES:
patent: 5554592 (1996-09-01), Quistad et al.
Slavnova et al., Doklady Akademii Nauk SSR, 297(2):492-494 (1987).
Visser et al., Comp. Biochem. Physiol., 75B(3):523,530 (1983).
Piek et al., Comp. Biochem. Physiol., 72C:303-309 (1982).
Spanjer et al., Toxicon, 15:413-421 (1977).
Visser et al., Toxicon, 14:357,370 (1976).
Walter et al., Neuroscience 9(1):213-224 (1983).
Drenth et al., Toxicon, 12:189-192 (1974).
R. L. Beard, Toxins of Animal and Plant Origin, vol. 1 deVries et al., Eds. Gordon and Breach Science Publishers, New York, 181-190 (1971).
T. Piek, J. Insect Physiol., 12:561-568 (1966).

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