Pesticidal peptides

Details Pesticidal peptides Pesticidal peptides

1999-04-21

2002-07-02

Eyler, Yvonne (Department: 1646)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C514S002600, C514S875000, C514S919000, C530S300000, C530S329000, C530S330000, C530S331000

Reexamination Certificate

active

06413530

ABSTRACT:

BACKGROUND OF THE INVENTION
Many blood-ingesting pests are known to feed on humans and animals, and many pests are vectors for pathogenic microorganisms which threaten human and animal health, including commercially important livestock, pets and other animals. Various species of mosquitoes, for example, transmit diseases caused by viruses, and many are vectors for disease-causing nematodes and protozoa. Mosquitoes of the genus Anopheles transmit Plasmodium, the protozoan which causes malaria, a devastating disease which results in approximately 1 million deaths annually. The mosquito species
Aedes aegypti
transmits an arbovirus that causes yellow fever in humans. Other arboviruses transmitted by Aedes species include the causative agents of dengue fever, eastern and western encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis, chikungunya, oroponehe and bunyarnidera. The genus Culex, which includes the common house mosquito
C. pipiens
, is implicated in the transmission of various forms of encephalitis and filarial worms. The common house mosquito also transmits
Wuchereria bancrofti
and
Brugia malayi
, which cause various forms of lymphatic filariasis, including elephantiasis.
Trypanasomacruzi
, the causative agent of Chagas' disease, is transmitted by various species of blood-ingesting Triatominae bugs. The tsetse fly (Glossina spp.) transmits African trypanosomal diseases of humans and cattle. Many other diseases are transmitted by various blood-ingesting pest species. The order Diptera contains a large number of blood-ingesting and disease-bearing pests, including, for example, mosquitoes, black flies, no-see-ums (punkies), horse flies, deer flies and tsetse flies.
Various pesticides have been employed in efforts to control or eradicate populations of disease-bearing pests, such as disease-bearing blood-ingesting pests. For example, DDT, a chlorinated hydrocarbon, has been used in attempts to eradicate malaria-bearing mosquitoes throughout the world. Other examples of chlorinated hydrocarbons are BHC, lindane, chlorobenzilate, methoxychlor, and the cyclodienes (e.g., aldrin, dieldrin, chlordane, heptachlor, and endrin). The long-term stability of many of these pesticides and their tendency to bioaccumulate render them particularly dangerous to many non-pest organisms.
Another common class of pesticides is the organophosphates, which is perhaps the largest and most versatile class of pesticides. Organophosphates include, for example, parathion, Malathion™, diazinon, naled, methyl parathion, and dichlorvos. Organophosphates are generally much more toxic than the chlorinated hydrocarbons. Their pesticidal effect results from their ability to inhibit the enzyme cholinesterase, an essential enzyme in the functioning of the insect nervous system. However, they also have toxic effects on many animals, including humans.
The carbamates, a relatively new group of pesticides, include such compounds as carbamyl, methomyl, and carbofuran. These compounds are rapidly detoxified and eliminated from animal tissues. Their toxicity is thought to involve a mechanism similar to the mechanism of the organophosphates; consequently, they exhibit similar shortcomings, including animal toxicity.
A major problem in pest control results from the capability of many species to develop pesticide resistance. Resistance results from the selection of naturally-occurring mutants possessing biochemical, physiological or behavioristic factors that enable the pests to tolerate the pesticide. Species of Anopheles mosquitoes, for example, have been known to develop resistance to DDT and dieldrin. DDT substitutes, such as Malathion™, propoxur and fenitrothion are available; however, the cost of these substitutes is much greater than the cost of DDT.
There is clearly a longstanding need in the art for pesticidal compounds that are pest-specific, that reduce or eliminate direct and/or indirect threats to human health posed by presently available pesticides, that are environmentally compatible in the sense that they are biodegradable, and are not toxic to non-pest organisms, and have reduced or no tendency to bioaccummulate.
Many pests, including for example blood-inbibing pests, must consume and digest a proteinaceous meal to acquire sufficient essential amino acids for growth, development and the production of mature eggs. Adult pests, such as adult mosquitoes, need these essential amino acids for the production of vitellogenins by the fat body. These vitellogenins are precursors to yolk proteins which are critical components of oogenesis. Many pests, such as house flies and mosquitoes, produce oostatic hormones that inhibit egg development by inhibiting digestion of the protein meal, and thereby limiting the availability of the essential amino acids necessary for egg development.
Serine esterases such as trypsin and trypsin-like enzymes (collectively referred to herein as “TTLE”) are important components of the digestion of proteins by insects. In the mosquito,
Aedes aegypti
, an early trypsin that is found in the midgut of newly emerged females is replaced, following the blood meal, by a late trypsin. A female mosquito typically weighs about 2 mg and produces 4 to 6 &mgr;g of trypsin within several hours after a ingesting blood meal. Continuous boisynthesis at this rate would exhaust the available metabolic energy of a female mosquito; as a result, the mosquito would be unable to produce mature eggs, or even to find an oviposition site. To conserve metabolic energy, the mosquito regulates TTLE biosynthesis with a peptide hormone named Trypsin Modulating Oostatic Factor (TMOF). TMOF mosquitoes produce in the follicular epithelium of the ovary 12-35 hours after a blood meal; TMOF is then released into the hemolymph where it binds to a specific receptor on the midgut epithelial cells, signaling the termination of TTLE biosynthesis.
This regulatory mechanism is not unique for mosquitoes; flesh flies, fleas, sand flies, house flies, dog flies and other insect pests which need protein as part of their diet have similar regulatory mechanisms.
In 1985, Borovsky purified an oostatic hormone 7,000-fold and disclosed that injection of a hormone preparation into the body cavity of blood imbibed mosquitoes caused inhibition of egg development and sterility (Borovsky, D. [1985
] Arch. Insect Biochem. Physiol
. 2:333-349). Following these observations, Borovsky (Borovsky, D. [1988
] Arch. Ins. Biochem. Physiol
. 7:187-210) reported that injection or passage of a peptide hormone reparation into mosquitoes inhibited the TTLE biosynthesis in the epithelial cells of the gut. This inhibition caused inefficient digestion of the blood meal and a reduction in the availability of essential amino acids translocated by the hemolymph, resulting in arrested egg development in the treated insect. Borovsky observed that this inhibition of egg development does not occur when the oostatic hormone peptides are inside the lumen of the gut or other parts of the digestive system (Borovsky, D. [1988], supra).
Following the 1985 report, the isolated hormone, (a ten amino acid peptide) and two TMOF analogues were disclosed in U.S. Pat. No. 5,011,909 and 5,130,253, and in a 1990 publication (Borovsky et al. [1990
]FASEB J
. 4:3015-3020).Additionally, U.S. Pat. No. 5,358,934 discloses truncated forms of the full length TMOF which have prolines removed from the carboxy terminus, including the peptides YDPAP, YDPAPP, YDPAPPP, and YDPAPPPP.
Neuropeptides Y (NPY) are an abundant family of peptides that are widely distributed in the central nervous system of vertebrates. NPY peptides have also been recently isolated and identified in a cestode, a turbellarian, and in terrestrial and marine molluscs (Maule et al., 1991 “Neuropeptide F: A Novel Parasitic Flatworm Regulatory Peptide from
Moniezia expansa
(Cestoda: Cyclophylidea)” Parasitology 102:309-316; Curry et al., 1992 “Neuropeptide F: Primary Structure from the Turbellarian,
Arthioposthia triangulata
” Comp. Biochem. Physiol. 101C:2

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