BACKGROUND ART Sexual behaviour in most mammalian species involves a complex series of male and female interacting behaviours. Disrupting these behaviours could offer a contraceptive effect. The contraceptive effect may have particular application in animal pest control.

It has long been recognised that modification of sexual behaviour in an animal may have applications in controlling animal aggression, accelerating growth, and control of population numbers. A common method of modifying sexual behaviour involves sterilization of animals, by physical castration. Problems associated with physical castration include infections, trauma to animals through handling, surgery and anaesthesia, risk of infection and the need for animals to be rounded up, and castrated by persons skilled in castration techniques and released.

Physical castration has been shown to have positive results in reducing animal aggression. However, it is well recognised that physical castration can have a deleterious effect on animal growth where steroids produced by the testes are no longer present to promote growth. There is accordingly a need for an easy to operate method of modifying sexual behaviour without resorting to physical castration. The present invention provides such a method.

The present invention also has applications in pest control.

Pest animal species are responsible for significant environmental damage, as well as having deleterious effects on human activities such as forestry, horticulture, and agriculture. Animal species cover a plethora of both vertebrate and invertebrate species. Damage is caused by the pests in many different ways including:

-competing for food with farmed animals; -damaging indigenous flora, especially through overgrazing; -destroying indigenous animal species through predation; -damaging agricultural, horticultural and silvicultural crops through grazing; and -acting as vectors for infectious agents.

Effective control of pests is an expensive and ongoing problem for which new and more effective solutions are constantly being sought.

Baiting programmes are commonly employed to control a wide variety of biological pests. However, a common problem associated with bait programmes is the development in an animal population of bait aversion.

Animal welfare concerns are also of considerable public importance. There is an expectation that methods used in controlling sexual behaviour of animals and biological pest control will not only be quick but also"humane". That is, any control techniques employed should ensure that the suffering of the animal is minimal and of short duration. Physical castration techniques may have drawbacks as noted above. Baits currently employed in poisoning programmes have resulted in many deleterious effects on the poisoned animal such as hyper-responsiveness to light and sound, ataxia, convulsions, and considerable gastric discomfort. The length of kill time can be as long as days to weeks depending on the level of toxin consumed.

The present applicants have now found that disrupting the function of pheromone recognition areas of the brain and the function of the vomeronasal organ in particular, can be used to modify sexual behaviour. More specifically, damage to the vomeronasal organ has been found to directly correlate with the degree of diminishment in sexual activity. Disrupting the pheromone recognition activity of the vomeronasal organ may therefore offer a long term contraceptive control option for animal pests. Compositions effective to disrupt the function of the vomeronasal organ would accordingly find use as contraceptive compositions, or even as lethal compositions, in animal control.

US Patent Specification number 5,290,914 discusses Bacillus thuringiensis toxins, Bacillus toxins generally and ribosome inactivating proteins such as ricin, dianthin, saporin, gelonin, tritin, abrin and modeccin as well as enzymes from seeds of barley, rye and wild bean and corn. Chemical toxins include methotrexrate and doxorubicin

among many others.

"Immunotoxins", chapter 37: Weir DM (ed) Handbook of Experimental Immunology, 4th Edition 1986 Blackwell, Oxford, provides a general discussion of toxins.

Use of ricin A in tumour targeting is discussed for example in Int. J Cancer 36: 705- 711 (1985); Vitetta et al., Science 219,644-650 (1983); Thorpe et al., Immunol. Rev 62, 120-158 (1982); Neville et al., Immunol, Rev 62,75-91 (1982); and Jansen et al., Immunol. Rev. 62,185-216 (1982).

Methods for obtaining lectin A chains are described in US Patent Specification 4, 590, 071.

Ghose T et al; Natl Cancer Institute: 61,657-676 (1980) discloses a wide variety of coupling agents.

Examples of conjugation procedures are provided in WO 90/06774.

Acetates known to attract Lepidoptera are disclosed in List of Sex Pheromones of Lepidoptera and Related Attractants, Arn, H, Tóth M, and Priesner E, (1992), International Organization for Biological Control; Montfavet, (2nd edition) by: Secrétariat general OILB-SROP/IOBC- WPRS, Station de zoologie, INRA, F-84143. Montfavet, France.

US Patent Specification 5,863,745 teaches of a recombinant antibody-toxin fusion protein which selectively kill cells bearing appropriate antibodies or receptors.

Specifically disclosed is a method for achieving targeted cytotoxicity.

US Patent Specification 5,372,822 discloses a method for chemically castrating male pigs in a manner that modulates the production of testosterone and interferes with the enzymatic conversion of testosterone into androsterone.

US Patent Specifications 4,527,000 and 4,722,839 describe novel diolefin insect pheromone mimics used to disrupt sexual communications between insects.

US Patent Specification 5,032,576 discloses a pheromone biosynthesis activating neuropeptide hormone controlling sex pheromone production in moths and controlling

melanization in moths. Untimely introduction of a synthetic analog of the hormone induced production of sex pheromone that resulted in deleterious morphological changes or death.

US Patent Specifications 5,738,688,5,631,229 and 5,707,964 teach of certain toxic compounds such as compounds based upon diphtheria toxin, ricin toxin, pseudomonas exotoxin, alpha-amanitin, pokeweed antiviral protein, ribosome inhibiting proteins, especially the ribosome inhibiting proteins of barley, wheat, corn, rye, gelonin and abrin, as well as certain cytotoxic chemicals such as, for example, melphalan and daunomycin can be conjugated to certain analogs of gonadotropin-releasing hormone to form a class of compounds which, when injected into an animal, destroy the gonadotrophs of the animal's anterior pituitary gland. Hence such compounds may be used to sterilize animals and/or to treat certain sex hormone related diseases.

US Patent Specification 4,081,533 discloses where the pre-ovulatory surge of luteinizing hormone from the pituitary gland is selectively suppressed or eliminated by introducing nonapeptide, 8-arginine. vasotocin, or the tripeptide, propyl-arginyl-glycinamide, into the subject. This results in loss of fertility.

US Patent Specifications 4,201,770 and 4,302,386 describe modified hormones or fragments of hormones useful in producing antibodies when administered to an animal which in turn cause neutralization of endogenous natural protein hormones. The protein hormones to which this procedure can be applied are mammalian protein reproductive hormones such as, for example, Follicle Stimulating Hormone (FSH), or Human Chorionic Gonadotropin (HGG). These modified hormones or fragments may be administered to animals for the purpose of contraception, abortion, or treatment of hormone related disease states and disorders.

US Patent Specification 4,400,376 teaches of an immunological preparation of an antigenic material in combination with a major histocompatibility complex antigen, which is itself in the form of complex with a protein with which it is normally associated in nature or with a modified form of such protein which retains the epitope thereof intact, said antigenic material being attached to the protein of the complex through antibody to that protein, is disclosed as being useful for the production of an immunogenic response in human or veterinary use.

US Patent Specifications 4,691,006 and 4,767,842 disclose endogenous and exogenous proteins, and fragments thereof, that are chemically modified outside the body of an animal so that when injected into the animal they produce more antibodies against the unmodified protein than would injection of the unmodified protein or fragment alone.

The chemical modification may be accomplished by attaching the proteins or fragments to carriers such as, for example, bacterial toxoids. The chemical modification can also be accomplished by polymerization of protein fragments. Proteins which can be modified include Follicle Stimulating Hormone and Human Chorionic Gonadotropin.

The modified polypeptides may be administered to animals for the purpose of contraception, abortion or treatment of hormone-related disease states and disease disorders, treatment of hormone-associated carcinomas, and to boost the animals resistance to exogenous proteins, for example viral proteins.

US Patent Specification 5,783,751 relates to a method of altering hypothalamic function in an individual. The method comprises nasally administering a human semiochemical, e. g. an Estrene steroid, or a pharmaceutical composition containing an Estrene steroid, such that the ligand semiochemical binds to a specific neuroepithelial receptor. The steroid is preferably administered in the form of a pharmaceutical composition containing one or more pharmaceutically acceptable carriers. Other embodiments of the invention include pharmaceutical compositions containing the steroids.

It is therefore an object of this invention to provide a method and composition which can be used to modify sexual behaviour in animals, which goes some way towards overcoming the above disadvantages or at least provides the public with a useful choice.

SUMMARY OF THE INVENTION Accordingly, in one aspect, the present invention can broadly be said to comprise a method of modifying or inhibiting sexual behaviour in an animal comprising disrupting the function of a pheromone recognition area of the brain of said animal.

Another aspect of the invention comprises a method of controlling sexual reproduction in an animal comprising disrupting the function of a pheromone recognition area of the brain of said animal.

Yet another aspect of the invention comprises a method of controlling an animal pest comprising disrupting the function of a pheromone recognition area of the brain of said animal pest.

Still another aspect of the invention comprises a composition comprising a disrupting agent specific to at least one cell surface protein present in a pheromone recognition area of the brain of an animal.

A further aspect of the invention comprises use of a composition of the invention in a method for modifying the sexual behaviour of an animal.

A still further aspect of the invention comprises use of a composition of the invention in a method for controlling sexual reproduction in an animal.

A further aspect of the invention comprises use of a composition of the invention in a method for controlling pests.

Preferably said pheromone recognition area is the vomeronasal organ.

Preferably disruption is achieved by administration of a disrupting agent specific to said pheromone recognition area.

Preferably disruption is achieved by administration of a disrupting agent specific to at least one cell surface protein present in said pheromone recognition area.

Preferably said disrupting agent is a toxin.

Preferably said disrupting agent is a toxin conjugated to a targeting moiety.

Preferably said targeting moiety comprises an agent specific for a binding site in the pheromone recognition area of the brain.

Preferably said targeting moiety comprises a pheromone or an immunoglobulin.

Preferably said toxin is domoic acid and the pheromone is dodecyl acetate or (Z)-7- dodecen-1-yl acetate.

Preferably said toxin is ricin A chain or domoic acid and said immunoglobulin comprises a monoclonal antibody raised to a cell surface protein present in said pheromone recognition area.

Preferably said toxin is domoic acid and said immunoglobulin comprises a monoclonal antibody raised to the NMDAR1 sub-chain of the NMDA (N-methyl-D-aspartate) glutamate receptor.

Preferably the compositions and disrupting agents of the invention are administered topically, orally, parenterally, or by inhalation.

Preferred aspects of the present invention will now be further described in relation to the accompanying drawings in which: Figure 1 is a graph correlating impregnation percentages with damage in the vomeronasal organ. Damage was effectuated by delivering a nasal spray containing domoic acid conjugated to dodecyl acetate in a water based form. Approximately 0.1 ml was delivered. Dodecyl acetate is a pheromone and thought to bind to the vomeronasal organ. Domoic acid is a known neurotoxin. The conjugation is thought to allow the domoic acid to accumulate in the vomeronasal organ.

Figure 2 is a graph correlating the percentages of pregnancy achieved with dosage of the conjugate supplied. The conjugate was delivered with a nasal spray containing domoic acid conjugated to NMDAR1 antibodies in a water based form. Approximately 0.1 ml was delivered. NMDAR1 is a sub-chain of the N-methyl-D-aspartate glutamate receptor which are present in abundance in the vomeronasal organ. Domoic acid is a known neurotoxin. The conjugation is thought to allow the domoic acid to accumulate in the vomeronasal organ.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to methods of modifying sexual behaviour in animals, and to the use of these methods in pest control.

As noted above, the present applicants have found that disrupting the function of the vomeronasal organ can be used to modify sexual behaviour. More specifically, damage to the vomeronasal organ has been found to directly correlate with the degree of diminishment of sexual activity. Disrupting the pheromone recognition function of the vomeronasal organ may therefore offer a long term contraceptive control option for animals, including animal pests.

In one aspect, the present invention can therefore be said to consist in a method of modifying sexual behaviour in an animal, the method comprising disrupting the function of a pheromone recognition area of the animal brain.

In a preferred embodiment, the pheromone recognition area of the animal brain is the vomeronasal organ.

In one embodiment for example, the method of the invention could be used to suppress sexual activity in non-castrate male animals. Advantages associated with this may be accelerated growth from the presence of testosterone and/or suppression of aggression associated with that. The animals remain fertile while sexual activity is stopped. This method is broadly applicable to animals of all types and sex, but may have particular application to male cats and dogs, bulls, stallions, rams, stags, boars, billy goats, roosters and the like.

More generally, the present invention relates to methods of modifying sexual behaviour in animals, and to the use of these methods in pest control. Target animals include mammals, marsupials, birds, insects, arthropods, amphibians and reptiles. The term "animal"is used herein generically to encompass all such groups. Of the mammalian group, application may be had to sheep, cattle, goats, pigs and the like. Rabbits, hares, deer, goats, mice, rats, and possums amongst others are contemplated as target pests.

Desirably, disruption of the function of the pheromone recognition area of the animal brain is achieved by administration of a disrupting agent specific to the area, and preferably to receptors specific to the area. The disrupting effect may apply equally to males and females of the species.

In another aspect, the present invention therefore provides a composition comprising an effective amount of a disrupting agent together with one or more diluents, carriers,

excipients or adjuvants.

The term"disrupting agent"as used herein refers to an agent capable of disrupting the function of a pheromone recognition area of the animal brain and as a result of this disrupting sexual function. This includes agents which act to block pheromone sensing, and agents which destroy the brain tissue, such as toxins. Neurotoxins are particularly preferred for use.

In one preferred embodiment, disrupting agents compromise a toxin portion and a target cell binding portion. A key feature of this disrupting agent is its selectivity.

"Selectivity"as used herein refers to the ability of the disrupting agent to bind to target cells, while not affecting the function of untargeted cells to any significant degree.

The toxin, or toxin portion of the disrupting agent may comprise any toxin known in the art for targeting and inactivating or killing cells. Suitable agents include naturally occurring and synthetically produced toxins. A plethora of bacterial, plant, fungal and animal toxins are known in the art. See for example US Patent No. 5,290,914 which discusses Bacillus thuringiensis toxins, Bacillus toxins generally and ribosome inactivating proteins such as ricin, dianthin, saporin, gelonin, tritin, abrin and modeccin as well as enzymes from seeds of barley, rye and wild bean and corn. Chemical toxins include methotrexrate and doxorubicin among many others. A general discussion of toxins may be found in"Immunotoxins", chapter 37: Weir DM (ed) Handbook of <BR> <BR> Experimental Immunology, 4thEdition 1986 Blackwell, Oxford. The patent and text are incorporated herein by reference.

Of these toxins, one preferred group are the ribosome inactivating proteins. Many such proteins are toxic lectins for example riacin, abrin and modeccin. Lectins are made up of two polypeptide chains A and B. It has been determined that ribosome inactivating function is associated with the A chain. Binding is associated with the B chain. In the absence of the B chain the lectin is effectively inactive. Lectin chains such as ricin A have found favour in immunotherapy methods, and in particular, in cancer treatment.

Use of ricin A in tumour targeting is discussed for example in Int. J Cancer 36: 705- 711 (1985); Vitetta et al., Science 219,644-650 (1983); Thorpe et al., Immunol. Rev 62, 120-158 (1982); Neville et al., Immunol, Rev 62,75-91 (1982); and Jansen et al., Immunol. Rev. 62,185-216 (1982). Methods for obtaining lectin A chains are described in US 4,590,071. Again these publications are incorporated herein by

reference. Ricin A chain may be purchased from Xoma Corporation, San Francisco, USA.

Another preferred group of toxins are neurotoxins including domoic acid, chlordane, botulinum toxin, and other amino acid based excitotoxins. Domoic acid is a currently preferred toxin.

The target cell binding moiety of the disrupting agent may comprise any moiety or substrate which is capable of binding the disrupting agent to a target cell. The target cells in this case are cells in a pheromone recognition area of the brain, and preferably in the vomeronasal organ.

Moieties or ligands (substrates that preferentially bind to a pheromone recognition area) capable of fulfilling the selective binding function required include peptides and proteins which bind to receptors on the target cells. Examples of such proteins include pheromones and immunoglobulins as well as active binding fragments thereof.

Examples of pheromones currently preferred for use herein are dodecyl acetate and compounds structurally related to dodecyl acetate. dodecyl acetate 0 Such preferred structurally related compounds include: 10-Methyldodecyl acetate (Z)-7-Dodecenyl acetate (R)-10-Methyldodecyl acetate (E)-7-Dodecenyl acetate (S)-10-Methyldodecyl acetate (Z)-8-Dodecenyl acetate Dodecenyl acetate 7, 7-Difluoro- (Z)-8-dodecenyl acetate (Z)-3-Dodecenyl acetate (E)-8-Dodecenyl acetate (E)-3-Dodecenyl acetate (Z)-9-Dodecenyl acetate (E)-4-Dodecenyl acetate ll, 1l-Difluoro- (Z)-9-dodecenyl acetate (Z)-5-Dodecenylacetate 11,11,11,12, 12-Pentafluoro- (Z)-9-dodecenyl (E)-5-Dodecenyl acetate acetate

(E)-9-Dodecenyl acetate (Z)-9-Dodecen-7-yn-1-ol acetate (Z)-10-Dodecenyl acetate (E, Z)-7,9-Dodecadienyl acetate (E)-10-Dodecenyl acetate (E, E)-7,9-Dodecadienyl acetate 11-Dodecenyl acetate (Z, Z)-8,10-Dodecadienyl acetate Dodecadienyl acetate (Z, E)-8,10-Dodecadienyl acetate (Z, E)-3,5-Dodecadienyl acetate (E, Z)-8,10-Dodecadienyl acetate (E, Z)-3,5-Dodecadienyl acetate (E, E)-8,10-Dodecadienyl acetate (E, E)-4,10-Dodecadienyl acetate 9,11-Dodecadienyl acetate (Z, E)-5,7-Dodecadienyl acetate (Z)-9,11-Dodecadienyl acetate (E, Z)-5,7-Dodecadienyl acetate (E)-9,11-Dodecadienyl acetate (Z, Z)-7,9-Dodecadienyl acetate (Z, E)-7,9,11-Dodecatrienyl formate (Z, E)-7,9-Dodecadienyl acetate A highly preferred compound structurally related to dodecyl acetate is (Z)-7-dodecenyl acetate: \ ° (Z)-7-dodecen-1-yl acetate) (Z)-7-dodecenyl acetate < The term"immunoglobulin"as used herein includes naturally occurring and recombinant immunoglobulins as well as fragments and derivatives thereof. Examples of immunoglobulins useful in the invention are monoclonal and polyclonal antibodies, and antigen binding fragments such as Fab, Fab', F (ab') 2, and FV. Preferred for use herein are monoclonal antibodies.

In terms of the present invention antibodies specific for pheromone recognition areas of an animals brain are required. In the case of the vomeronasal organ, it is believed to contain species specific receptors. Antibodies for specific receptors are most desirably produced using known art methods.

The production of species-specific antibodies for conjugation to toxins for use in pest control is also contemplated. The technology has particular application to destruction of targeted pests species other than simply through modifying sexual behaviour.

Monoclonal antibodies against surface receptors of target cells may be made by somatic cell hybridization procedures originally described by Kohler et al, Nature (1975) 256: 495-497. Recombinant methods such as those described by Huse et al., Science 246: 1275-1281 (1989) can also be used. The procedure is well known and has been extensively documented in the art. Fragments may be produced by digesting the whole immunoglobulin with appropriate proteases such as pepsin or papain. Again this process is well known.

Polyclonal antibodies may be produced according to the method used by Koelle et al ; Cell 67: 59-77,1991 incorporated herein by reference.

Antisera is recovered by any of the absorption techniques known in the art see for example Handbook of Experimental Immunology 4th Edition, Blackwell, Oxford incorporated herein by reference.

Once produced the toxin and the target cell binding moiety are coupled together to produce a disrupting agent. Many suitable coupling techniques are known in the art.

For example, a wide variety of coupling agents is disclosed in Ghose T et al; Natl Cancer Institute: 61,657-676 (1980). The use of carbodimides as well as bifunctional regents such as glutaraldehyde, p-benzoquinone, dimethyladipimidate and heterobifunctional regents such as N-succinimidyl-3- (2-pyridyldithio) propionate (SPDP), m-maleimidobenzoyl-N-hydroxy-succinimidyl ester, bromoacetyl-P- aminobenzoyl-N-hydroxy-succinimidyl ester, and iodoacetyl-N-hydroxysuccinimidyl ester amongst others are taught. The paper is also incorporated herein by reference.

Any other coupling agents commonly known in the art may also be used. Examples of conjugation procedures are also provided in WO 90/06774.

The conjugates produced, for example dodecyl acetate or (Z)-7-dodecen-1-yl acetate (pheromone)/domoic acid (toxin) conjugates act with the pheromone portion binding to the vomeronasal organ. The conjugation is thought to allow domoic acid (the toxin) to accumulate in the vomeronasal organ.

Disrupting agents produced may be further modified after production if desired. For example, slow release formulations may be desired. The agents may be further combined with diluents, excipients and carriers, colourants, flavouring agents and the like. The final composition may be formulated for oral, parenteral, intranasal, or

intravenous administration amongst others. Tablets, liquids, pastes, sprays, emulsions and powders may all be appropriate formulations depending on the target animal selected.

The reader will appreciate that compositions produced using the methods described above may be specific for pheromone recognition areas of selected animal species. It is important to note that some, but not all of these sites will be species selective.

However, the same technology can be used to deliver lethal doses of toxin to a wide range of pest species on a species specific basis. Selectivity is achieved by altering the target cell binding portion of the disrupting agent. Targets selected for administration of toxin where a lethal result is required may include the digestive, nervous, autonomic nervous system or selected target organs such as the brain, heart, liver and the like.

Further, while the disrupting agents will generally be used to target a toxin to a single pest species groups of pests can also be targeted selectively, for example mice and rats, or a range of insects, but with little or no effect on non-targeted species.

In one aspect, the composition of the invention is formulated as a bait composition.

Bait compositions have particular application in methods of controlling pest species in the wild. Particularly possums, rats, mice and wasps but not limited thereto. The reader will appreciate that using the techniques of the present invention species specific disrupting agents can be produced for formulation into bait compositions. These compositions may comprise any known bait suitable for use in administering the disrupting agent to the selected pest species.

Administration herein includes making the composition available in the pests' environment or administration by injection, inhalation, consumption or other suitable means.

Examples of preferred baits for use herein included commercial liquids, pastes, tablets and foodstuffs such as meats and vegetables. In addition to the compositions of the invention the baits may include other known components such as attractants (these may be chemical or colour attractants for example), stress inhibitors, and the like. The compositions may be formulated using known art methods such as powder coating, mixing, dissolving or injection as required.

The composition is made available in the environment of the targeted animal by conventional methods including incorporation into foodstuffs, aerial drops, spraying and hand laying as required to name a few.

In one preferred embodiment, the bait composition may be formulated as a spray at a bait station. Activation of the delivery device, usually by animal triggering delivers a spray or mist which the animal inhales. Accordingly, in some embodiments the bait composition of the invention may be used in conjunction with known bait systems and stations, rather than as an alternative thereto.

The compositions of the present invention have a number of uses. Where modification of the sexual behaviour of commercially important (eg cattle, sheep, pigs, goats, deer etc) or domesticated animals (eg cats, dogs, horses etc) is required a composition of the invention may be administered. The composition will include a disrupting agent specific for the pheromone recognition areas of that species brain. Damage to the brain area responsible for recognition of pheromone signals is shown to diminish sexual activity. Accordingly, there is provided a safe, relatively inexpensive way of achieving a long-lasting contraceptive effect in such animals. This is a useful alternative to surgical castration. An advantage of using such compositions is that testosterone generated by the testes is still circulating and promoting growth while reducing or eliminating aggressive tendencies often associated with this. The animals also remain fertile.

The compositions of the invention can similarly be used to control pest species where the contraceptive effect will result ultimately in a decrease in animal population numbers. The technology can also be applied more generally to target essential animal organs and systems to achieve a lethal effect on administration as opposed to a contraceptive effect.

Targeting specific organs with highly lethal toxins can provide a quick and relatively humane method of killing pest species.

The compositions and methods of the invention are particularly useful where species specific targeting means that non-target animals in the same environment remain essentially unharmed.

Certain aspects of the invention will now be described in relation to the following non-limiting examples.

Example 1 Preparation of pheromone/neurotoxin conjugate.

Domoic acid was weakly bound by hydrogen atoms to dodecyl acetate or (Z)-7- dodecen-1-yl acetate, according to know art methods, in a 1: 1 ratio. The resultant conjugate soluble in water at slightly acid pH (pH < 6.9). This solution was put into a spray container and delivered into the nose region of the male rats at approximately a 0.1 ml volume.

Example 2 Effect of pheromone/neurotoxin conjugate on male rat brain.

10 male rats, prior to the toxin exposure, were presented with 1 new female rat in estrus per week for 5 weeks. The total percentage pregnancy from this group of 50 females was 80%.

The male rats were then treated with the spray and two weeks later re-exposed to the five week period of estrus female exposure.

Three months after the treatment the rats were sacrificed and the vomeronasal organ examined for histological damage.

The degree of damage varied greatly from no evidence of damage to 40-55% cell damage. This variation in individual damage correlated well with successful impregnation of females following the treatment.

As can be seen in Figure 1 at levels of damage greater than 20% impregnation success was less than 20%. At levels of damage higher than 30% no impregnation occurred. The variation in damage probably relates to the method of delivery. A more precise dose into the nose would likely provide uniform results.

Dodecyl acetate and (Z)-7-dodecen-1-yl acetate were found to be equally effective.

Example 3 Preparation of monoclonal and polyclonal antibody specific for rat. Following the known art of protocols, the immunisation of female BALB/c mice may be carried out according to the following protocol: Week Antigen Amount of Adjuvant Blood Administration Antigen Sampling 0 1 50-10'0, ug Alum 1 2 2 50-100, ug Alum 3 1st 4 3 50-100, ug Alum In all cases, the antigen is an antigenic compound of the invention, and the injection is intraperitoneal. Two booster injections are given at two weekly intervals. The booster injections comprise 50-100, ug of immunogen (100-200, ul of antigen/adjuvant mix) per mouse with a 50: 50 mix of adjuvant to antigen complex. 4-5 days following the last injection, the mice are either exsanguated, their blood collected, and polyclonal antibodies isolated from serum; or the mice are killed, and their spleens removed.

Spleen cells are cultured and antibodies produced are isolated according to conventional protocols.

Example 4 Proposed preparation of rat monoclonal antibody/toxin conjugate following the protocols in Vitetta et al, Immunol Rev 62: 159-183 (1982) and US 4,664,911.

Add 10, ul of 60 mM dithiothreitol (DTT) in PBS to each mg of dialyzed ricin A chain (available from Xoma Corporation, San Fransisco, USA). Incubate the mixture at 25°C for 60 minutes and separate the reduced chain from the DTT by gel filtration at 25°C on a Sephadex G-25 column in PBS at PH 7.2. Couple antibodies as described in Vitetta (referenced above) and mix with reduced A chain at an antibody A chain

molar ratio of 5: 1. Incubated the mixture with gentle shaking at 4 °C for 15 minutes and then dialyze overnight against PBS at 4°C. Concentrate the immunotoxin produced to 1 mg/ml by pervapouration, dialyze for 2-16 hours at 4°C against PBS and centrifuge to remove insoluble material. Separate the immunotoxin from the majority of free A chain and antibody by gel filtration at 25°C on a Sephacryl-S200 column equilibrated with PBS, pH 7.2.

Pool material with an apparent molecular weight of greater than 200,000. Add reduced and alkylated bovine alpha globulin, fraction 4 (Sigma) of a final concentration of 1 mg/ml to the pooled samples. Store the samples for 16-20 hours at 4°C prior to affinity purification.

Affinity purify the rat Ig-A chain (Rat) immunotoxins on Sepharose-Ig. For purification of the A chain-containing immunotoxins, equilibrate and wash the columns in PBS, pH 7.2. Apply samples to the column and discard the fall-through.

Extensively wash the columns in PBS (or PBS-0. lM gal) followed by 0.85% NaCl.

Elute immunotoxins batch-wise at 37°C with 2-3 column volumes of 3.5 M MgCl2.

Remove the MgCl2 by dialysis and concentrate the samples by pervapouration to approximately 200-300 ug/ml. Add reduced and alkylated bovine alpha globulin to a final concentration of 1 mg/ml. Sterilize samples by filtration [on a filter prewetted with PBS 2% fetal calf serum (FCS)], and then aliquot into sterile vials and store at- 20°C. Each immunotoxin contains one or two A chain subunits per molecule or antibody. Samples stored in this manner can be stable for up to 4-6 months.

Example 5 Preparation of rat monoclonal antibody/toxin conjugate following the protocols in Vitetta et al, Immunol Rev 62: 159-183 (1982) and US 4,664,911.

Commercial antibodies (Sigma Immunochemicals) to the NMDAR1 sub-chain of the NMDA (N-methyl-D-aspartate) glutamate receptor were obtained. These were conjugated to domoic acid as described in Example 4.

Example 6 Effect of antibody/neurotoxin conjugate on male rat brain.

Three groups of 5 male rats (Sprague Dawley, 300-400g bodyweight) were each provided with 10 females in oestrus over three days and resultant pregnancy rates measured.

Following this the first group of rats was treated with a control nasal spray (0.1 ml), the second group with a nasal spray containing a diluted 1: 20 ratio titre of the conjugate antibody-domoic acid from Example 5 and the third group with a 1: 10 ratio titre of the same.

Three weeks after this single treatment each male was again provided with 10 females over three days and pregnancies resulting recorded.

The group that received the control was not affected. Groups that received the domoic acid-glutamate subchain receptor antibody conjugate show marked reductions in pregnancy success. These results are depicted in Figure 2.

Glutamate receptors are present in abundance in the vomeronasal organ. This clearly demonstrates the use of an antibody conjugate for targeting the vomeronsal organ.

However, it is not species specific as the glutamate receptor and its NMDAR1 subchain are homologous across mammalian species.

It will be apparent to those skilled in the art that the use of a species specific surface protein to develop a species targeting antibody is anticipated from this proof of delivery concept.

It will be appreciated by those persons skilled in the art that the present invention is provided by way of example only and that the scope of the invention is not limited thereto.