IE873366L - Administering interferon to cattle - Google Patents

Abstract

The measures entail systemic administration to young cattle of a prophylactically effective amount of bovine interferon before infection with an infectious pathogenic virus or microorganism has taken place or is disseminated. [EP0271447A2]

Description

9 917 - i - This invention is directed to the field of animal health and, more particularly, to providing a medicament for reducing the incidence of bovine respiratory disease complex, the causes of which lie in a number of factors. 4 Several forms of respiratory diseases in cattle, commonly referred to by the collective terra "Bovine Respiratory Disease Complex (BRD)", have become known.

This bovine-specific disease of the respiratory organs is a principal cause of loss in the cattle industry.

One form of this disease, (BRD), the so-called "Shipping Fever®, occurs primarily in newly weaned calves, generally within the first week after the calves are moved to feedlots, because they are exposed to great stress as a result of handling, transportation and possibly inclement weather conditions. 1 5 ^Shipping Fever® is one of the most prevalent and economically significant cattle diseases, affecting the Worth American cattle industry with losses of between 250 million and 1 billion dollars annually.

A second form of "BRD" is "Esxzootic Calf Pneumonia®, which particularly 20 affects calves housed in closed stalls generally in the first month of life.

The affected calves develop symptoms of acute respiratory disease and may eventually die as & result.

Other calves by contrast undergo a milder course of the disease, which 25 is associated with irritation of the mucous membranes of the nose sad eyes.

During the further course of the disease, the calves affected may either develop more acute symptoms of the disease or, by contrast, may recover, in which case however a second outbreak of disease within a period of a few weeks is possible.

While this disease is most commonly encountered in cattle intended for the production of meat, it is also found in dairy cattle. All ages are 5 susceptible to the disease, but it most commonly occurs in newly purchased young cattle that have recently been introduced into a herd. In some cases, the introduction of new dairy cattle into an existing herd may even be followed by an outbreak of pneumonia in the original stock. 1 o The diseases comprised under the collective term bovine respiratory disease complex are believed to be caused by a series of factors, such as by damage to the respiratory tract and/or by stress. Damage to the respiratory tract may be caused by, for example, viruses such as bovine herpes virus, or by different mycoplasma and/or chlamydia strains. 15 Stress may be caused by, for example, weaning, castration, overcrowding, temperature changes and secondary infection by bacteria such as the various Pasteurella species.

Viral infection and stress may combine to cause immunosuppression in affected cattle. This immunosuppression may then promote secondary 2 0 colonisation of the lungs with bacteria (principally Pasteurella haemolvtlca') (see Joseph M. Cummings, "Feedlot Disease and Parasites" in The Feedlot. G.B. Thompson and Clayton C. O'Mary, ed. , Lea. and Febiger Philadelphia, Third Ed. , 1983).

Predisposing factors, therefore, are of decisive importance in 25 susceptibility to "Shipping Fever69 or "Enzootic Calf Pneumonia-. Among the most prevalent of these are physical stress factors, chemical agents and psychological factors.

Physical stress factors include weaning, temperature extremes and rapid changes in the weather, husiditv, irregular feeding and catering of the 30 animals, changes in feed rations, dust, overcrowding, and the herding and confining of the animals.

The stress suffered by calves recently arrived at cattle yards or feedlots due to their consequent treatment is considered to be a major cause of the outbreak of pneumonia. In general the calves are vaccinated, dehorned, castrated and treated with vitamins and antibiotics directly after their arrival. These procedures are frequently performed on cattle that are exhausted after transport in cattle lorries under confined conditions.

Chemical agents that may cause stress include ammonia fumes and toxic gases which may be generated within farms.

Additional diseases such as parasite attack have also been demonstrated to have an adverse effect on the ability to resist infection.

All these factors induce pathological changes such as depression of the isEsime system (for example endogenous steroid release with resulting impairment of neutrophil and lymphocyte function) and paralysis or inhibition of mucin secretion in the respiratory tract.

Asong the best-known viruses implicated in bovine respiratory disease complex are bovine herpes virus type I (BHV-1 or infectious rhino tracheitis virus), parainfluenza virus type 3 (PI-3) , the virus causing bovine viral diarrhoea (BVD) and bovine respiratory syncytial virus (BRSv).

Viruses may cause immunosuppression by several mechanisms. They are able, for example, partially or wholly to impair lymphocyte functions or lower the activity of the body's own bactericidal mechanisms, especially those involving macrophages and neutrophils, are normally responsible for keeping Gram-negative bacteria away from the lungs.

The viruses alter the ability of macrophages to digest antibody-coated bacteria (decreased Fc receptor activity). Even if the macrophages are still able to take in the bacteria, there is a marked reduction in the destructive efficiency of virus-infected macrophages. Furthermore, ic has been shown that viral infection can greatly reduce the production of - k - chemotactic substances by alveolar macrophages and therefore dramatically influences neutrophil nenewal in the lung.

Viral infection may also alter neutrophil mobility and induce dysfunctions.

Finally, if the alveolar macrophages express viral antigens on their surface, either due to replication or phagocytosis of viruses, the cytotoxic T cells may be directed against the macrophage cells themselves, further impairing their functioning.

As mentioned earlier, viral infections and stress appear to enhance 1 0 colonisation of the respiratory tract by both Gram-positive and Gram-negative bacteria.

Although there are a variety of bacteria that can colonise the lung and cause pneumonia, the majority of bovine pneumonias are caused by Pasteurella haemolvtica A-I.

In addition to Pasteurella haemolvtica. Pasteurella multocida and Haemophilus somnus are also commonly found in samples isolated from the respiratory tract of animals suffering from a disease encompassed by bovine respiratory disease complex, as are various Mycoplasma species (Mycoplasma bovis. Mycoplasma dispar and Mycoplasma bovirhlnis).

After rapid multiplication of P. haemolvtica in the region of the nasopharynx, the bacteria can, for example, enter the lung inside very fine droplets.

Furthermore, P. haemolvtica produces a soluble cytotoxic (leucotoxin) that can directly impair the function or cause the death of ruminant 2 ^ leucocytes.

After phagocytosis of the bacteria, alveolar macrophages and neutrophils may be damaged or killed. Dead neutrophils in the lung contribute to the lesions caused by pneumonia.

The disease usually breaks out within & period of 3 to 15 days after the animals have suffered great stress.

Affected calves usually appear lethargic and are without appetite. A mucopurulent nasal discharge and a surface cough are common. The j- respiratory rate is increased from a normal value of 30 per minute up to 80 to 100 per minute. Diseased calves also have an increased body temperature ranging from 40°C to 41°C.

Examination of the lung with a stethoscope usually reveals evidence of bronchopneumonia or even of plaurisy. 1 q Pasteurella haemolvtica induces severe pulmonary lesions. Fibrin depositions and capillary thromboses are among the main pathological features of pasteurelloses.

For the cattle industry the losses caused by diseases encompassed by bovine respiratory disease complex are the results not only of the death 15 of affected &zixm&ls, but also of the costs of tresvment, weight loss, inefficient feed conversion and extra working hours resulting from the disease.

Therefore, in the search for adequate methods of treatment, it has been proposed to reduce the incidence and severity of respiratory diseases in cattle by administering interferons.

"The interferons (IFM) are a family of proteins classified into three types and labelled cs, 0 and 7. This classification into three groups is based upon antigenic structure, geae organisation, structure, pH sensitivity, cellular origin and biological activity of the interferon proteins.

The different types of interferons may be obtained from, for example, 25 aemsals, such as cattle, pigs or even humans.

The expectation that it might be possible to reduce the incidence and 6 severity of respiratory diseases by treatment with interferon has been given greater weight by model studies. In one such model study, cattle were infected artificially with herpes viruses (BHV-1). The subsequent administration of human interferon led to a reduction in the severity of 5 the infection. See Ronev et al.. Am. J. Vet. Res.. 46. 1251-1255, 1985.

In comparable model studies by Ohmann and Babiuk [J.Inf.Res. 5(4): 551-564 (1985)] the action of recombinant bovine interferon on the natural cell-mediated cytotoxicity is investigated. To demonstrate this action the authors make use of both an in vitro [leucocyte treatment] and an in .j q vivo [treatment of artificially BHV-1-infected calves] test system. In both cases it was possible to determine a positive effect on the cell-mediated cytotoxicity.

Czerniecki et al. [Antiviral Res., Suppl. 1 : 209-215 (1985)] describe in vitro experiments indicating the ability of BoIFN-cjl to inhibit the 15 replication of a number of viruses implicated in BRJD. In addition, in vivo model studies are presented which were carried out using calves infected artificially [combined infection with BHV-1 and Pasteurella haemolytical.

Babiuk et al. [J.Gen. Virol.66 : 2383-2394 (1985)] report on in vivo 20 experiments with the BHV-1/Pasteurella haemolvtica disease model. In the course of these investigations it was possible for the first time to demonstrate a prophylactic activity of intranasally administered bovine interferon with regard to the consequences of artificial infection with a specific viral strain of BHV-1 and a defined Pasteurllla [sic] haemolvtica pathogen, within the framework and under the specific and 2 5 standardised conditions of the model.

However, model studies generally have a deep flaw. For example, in the present case the cattle were not subjected to a combination of stress factors and to a multiplicity of different viruses and microorganisms, as is the case under actual field conditions, in which the cattle are 30 passed through cattle auctions, fssdlots and by cattle yards; all this , contributes to the cattle being in & labile physiological condition, characterised inter alia by a temporary immune deficiency, as a result of which these animals are particularly susceptible to infectious diseases.

In addition, the cattle employed in the modal experiments described are specially selected animals which are seronegative for the pathogens used in the model, the animals first being treated with interferon and only than artificially infected with a specific virus, BHV-1, strain 108, in a targeted manner and at a precisely defined point in time. After © period of 4 days there is a second infection with a liltewise defined, superinfecting bacterial pathogen [P&sneural La h&smolytics,, bio type A, serotype 1].

Successful model studies do not, therefore, necessarily mean that cattle can be treated successfully under actual field conditions with bovine interferon so as to prevent the entirety of the infectious respiratory diseases encompassed by the term bovine respiratory disease complex. In addition, such studies contain only to a very limited extent data on the optimum boundary conditions for interferon treatment in order to reduce the incidence and severity of infectious respiratory diseases under field conditions.

Questions as to be best time for inoculation and the most beneficial method of inoculation therefore remain unanswered.

The object which it was for the invention to achieve therefore relates to the provision of a medicament which can be employed, under practical conditions for the prophylactic treatment of young cattle kept in close confinement and predisposed by stress, chemical agents and psychological factors to bovine respiratory disease complex,, for the prevention of the diseases encompassed by this term.

As is evident fros the detailed description of the invention which now follows, this object and othars have been successfully achieved within the scope of this invention, surprisingly, by the use of a recombinant bovine «-interferon for the preparation of a corresponding medicament.

The invention therefore relates primarily to the use of a recombinant bovine a-interferon for the preparation of a medicament for the single, intramuscular, prophylactic treatment of young cattle kept in close confinement and predisposed by stress, chemical agents and psychological factors to bovine respiratory disease complex, for the prevention of this disease.

The said medicament contaiiis the recombinant bovine a-interferon preferably in a single dose of from 0.5 mg to 250 mg, particularly preferably in a single dose of from 1.0 mg to 50 mg and very particularly preferably in a single doss of from 3.0 mg to 10 mg.

Description of the invention Interferons which can be used within the scope of this invention for the preparation of a medicament for the single, intramuscular and prophylactic treatment of cattle kept in close confinement and predisposed by stress, chemical agents and psychological factors to bovine respiratory disease complex primarily comprise bovine cs-interferons prepared using recombinant DM technology.

All three types [e, (5 and 7] of interferon can play a direct role in the control of viral replication in the infected cells. They are &1 so involved in the regulation of the immunological functions. All interferons are able to stimulate and increase the first stage of immunological defence: phagocytosis and cell destruction.

Within the scope of the invention interferons of the o type are employed which are formed naturally by lymphocytes and other leucocytes as a response to a viral infection.

The cloning and expression of DNA fragments which code for bovine cs-interferon has shown that the bovine genome contains two different classes of c-genes: the BoIFN-cj and the BoIFgenes. These classes of genes consist of 10-12 and 15-20 subtypes respectively. The gene which codes for BoXFM-Cjl, a subtype of the BoIFN-aj family, has been cloned and expressed in bacterial cells to determine its in vitro and in vivo activities.

Recombinant bovine c.j-interferon (rBoIFMcsjl) , for example, is a basic protein composed of 166 amino acids. Its molecular weight is 19,000 daltons.

Formulated interferon is usually stored in a lyophilised (freeze-dried) form. Alternative forms which can be used are ready-formulated injectable solutions.

The lyophilised interferon may be reconverted to a form suitable for administration by adding a suitable diluent, preferably sterile water.

The functionally reconstituted interferon is administered systemically to young cattle by any conventional method, such as by injection. Systemic administration may be made intramuscularly, preferably into the region of the rump, subcutaneously, or intravenously.

Particularly preferred within the scope of this invention is the use of recombinant bovine o-interferon for the preparation of a medicament, which can be administered intramuscularly, for the single, prophylactic treatment of cattle kept in close confinement and predisposed by stress, chemical agents and psychological factors to bovine respiratory disease complex, for the prevention of this disease.

Within the meaning of the invention the term young cattle is intended to denote those of an age between a few days and 18 months, but in particular between 6 and 18 months.

The amount of interferon administered preferably corresponds to a prophylactically effective dose. The lower limit is 0.5 sag of IFN/animal, preferably 1 mg of IFN/animal, in particular 3 mg of IFH/animal.

The upper limit represents the maximum amount of interferon which can just b® tolerated by the animal under treatment without severe side-effects.

The upper limit is, for example, 250 mg of IFN/animal, preferably 50 mg of IFN/animal arid very particularly preferably 10 mg of IFN/animal.

The optimum amount of interferon is in the range from 3 mg of IFN/animal to 10 mg of IFN/animal, in particular 5 mg of IFN/animal.

The medicament provided within the scope of this invention consequently contains the recombinant bovine e-interferon in a single dose of from 0.5 mg to 250 mg, particularly preferably in a single dose of 1.0 mg to 50 mg and very particularly preferably in a single dose of from 3.0 mg to 10 mg.

The functionally reconstituted interferon may be in any convenient concentration, for example, it is possible for injection of 5 mg of IFN/animal to prepare an 1FN solution of 2.5 mg of IFN/ml of solvent (preferably sterile H20) and to administer 2 ml of this solution per animal.

As could ba demonstrated by pharmacokinetic studies, after only -20 hours more than 90 t of the amount of interferon administered is eliminated.

Treatment with interferon should therefore preferably be carried out prior to, or directly after, exposure to infectious pathogenic microorganisms.

The preferred time period for the administration of the IFN comprises a time span of -72 to h-24 hours, preferably -SO to -s-20 hours, relative to the time of infection with an infectious pathogenic microorganism.

Administration is particularly preferred before the onset of infection, in particular during a period of -50 to -10 hours based on the time of infection with an infectious pathogenic saicroorganism. .11 The exact timing of interferon administration is important since, in the majority of cases investigated, the respiratory diseases occur either shortly after the coming together of the animals at cattle auctions, during transportation, or else on entry into the feedlots.

It is therefore advantageous to treat the animals with interferon at the first possible opportunity at the place where they are collected together before actual fattening, i.e. at cattle auctions, in cattle yards or in feedlots.

The efficiency and ciode of action of interferon has been demonstrated in 1 q this invention both by in vitro and in vivo experiments. It was possible to demonstrate the clinical efficiency of interferon administration both in a model study based on a reproducible disease model and using field trials.

No IFN treatment-related adverse reactions were noted during field ^ trials on a total of 3000 calves treated intr anas ally and approximately 7000 animals treated intramuscularly. It was also impossible to demonstrate any adverse effects on animals which, simultaneously with the treatment with interferon, were subjected to the normal treatment procedures which are carried out routinely in the course of processing 20 animals reared for fattening, for example worming, vaccination, ectoparasicicids.1 treatment, the implanting of anabolics, the application of branding marks and the introduction into the feed of growth promoters and antibiotics.

A controlled study was able to demonstrate that concurrent intranasal or 25 intramuscular treatment with recombinant bovine es-interferon and vaccination with modified live IBR/FI-3 virus vaccines has no adverse effects on the animals under treatment and results, moreover, in no impairment of the protective effect of the vaccine.

The efficiency of interferon treatment in reducing the incidence and the severity of respiratory disease in cattle, which could be demonstrated within the scope of this invention in extensive model studies and field trials, is evident from a significant reduction in the incidence and the mortality rate, a significant reduction in the severity of the disease and the number of sick days per animal or group as well as in an improved weight gain and feed conversion of the treated animals compared 5 to the controls.

The examples given below serve only to illustrate the subject of the invention as described above, without in any way limiting it.

Examples 1. Bovine interferon A method for producing bovine interferon is disclosed in Japanese Patent Application 58,224,690 and in EP-A-0 088 622, published on September 14, 1983 and entitled "Animal Interferons, Processes Involved In Their Production, Compositions Containing Them, DNA Sequences Coding Therefore [sic] and Expression Vehicles Containing Such Sequences and Cells 1 5 Transformed Thereby85. 2. Pharmacokinetics and toxicity Serum distribution and bioavailability of rBoIFW-Gjl was studied after intranasal, intramuscular and intravenous administration of a single dose of 10 mg per calf.

The half-lives range between 130 and 270 minutes. For all methods of application more than 90 % of the total administered dose is eliminated within 15 hours after administration and the bovine interferon level falls below the level of detection after 24 hours.

Approximately 40 % of the intramuscular dose is available to the 25 circulatory system.

No toxic affects from interferon can be seen in animals treated for 15 consecutive days with doses of up to 25 mg intranasally administered.

Levels of interferon in the serum on the loth day are found to be only slightly above the background levels.

Previous experiments have shown that a single dose of 100 mg per head is readily tolerated.

^ Transient mild leukopenia and a moderate pyretic response are in many cases observed following an initial intramuscular dose. However, leucocyte counts and temperature return to normal values very quickly at the very latest within 24 hours to 4 days. Repeated daily dosing does not further affect these depressions, which do not appear to influence ^ o the clinical condition of the animals, nor the prophylactic action of the interferon, in any way. 3. In vitro studies of interferon activity a) Antiviral activity in vitro: The antiviral potency of rBoIFN-csjl is assayed on bovine cell lines 15 infected with different bovine-specific viruses. Activity titres, commonly expressed in units U/al or converted to units U/mg protein (specific activity), represent the reciprocal of that dilution which results in 50 % inhibition of the virus- induced cytopathic effect (plaques). rBoIFM-Cjl inhibits viral replication by those viruses most commonly isolated from cattle that suffer from HBRDS (BVDv, PI- 3, BRVS [sic] and IBR/BHv-1). b) Immunomodulatory effects in vitro: To assess the immunomodulatory effects in vitro bovine phagocytically 25 active cells (neutrophils, blood monocytes and alveolar macrophages) are treated with rBoIFN-ctjl.

The effects observed are manifold and comprise for example enhanced bacterial uptake by all three cell typas, increased Fc receptor activity in alveolar macrophages, inhibition of both directed and random migration of monocytes and polymorphs, increased enzyme release or inactivation, increased hydrogen peroxide generation and decreased peroxide-amine release by alveolar macrophages and PMN leucocytes.

These effects are dose- and time-dependent. 4. Immunomodulatory effects in vivo A variety of leucocyte functions were investigated in the course of an experimental mixed infection with BHV-1/?. haemolytica. carried out to determine whether interferon also plays an immunomodulatory role in vivo 10 thus results in a reduction in incidence of disease and mortality.

In the model, peak immunosuppression occurs 4 days after injection, which is a time whan susceptibility to bacterial infections is at a maximum.

To determine the effect of recombinant bovine interferon on neutrophil 15 migration and chemotaxis, the neutrophils present in the peripheral blood of interferon-treated or control animals are measured in a migration and chemotaxis assay.

In both cases, neutrophil function is suppressed as a result of infection.

The group created with interferon, however, returns to normal values much more rapidly than the control group.

Further modification of neutrophil function can be demonstrated in a chemilumlnescence assay by measuring the rate of production of reactive oxygen derivatives. Using this assay, it can be demonstrated that 2 5 interferon treatment dramatically increases the ability of neutrophils co produce reactive oxygen derivatives in animals injected with P. haemolytica.

. Field trials: "Shipping Fever" In a first study series, 770 purchased steers were shipped by lorry to a cattle auction and then to a feedlot. On arrival the animals were randomly assigned to Identical pens. Each test animal then received 5 mg 5 of rBoIFN-Cjl per nostril in a dose of 2 ml of solution or an equivalent volume of a placebo.

Clinical symptoms which occur, such as depression, loss of appetite or respiratory symptoms, are recorded (see page 20). Sick animals were treated with antibiotics. 1 0 The results are given in the following table.

Table 1: Treatment Disease Average Feed Increase in group incidence1 number of conver- weight (%, day 1-30) sick days sion (kg/day) 1 5 per animal Placebo 38.2 0.956 6.6 0.91 rBoIFN-csjl 31.9 0.839 6.0 1.0 1 Number of sick animals/total number of animals These field trials show that the number of animals suffering from a 2o respiratory disease (incidence) and the nus&ber of sick days per animal are significantly reduced in the animals treated with IFN in comparison to the controls.

Likewise, weight gain and feed conversion are significantly better in the IFN-treated animals.

In another study, conducted in a research feedlot, the effect of a single dose administered as an intramuscular injection (10 sag of 16 - IFN/animal) or intranasally (5 mg of IFN/nostril) were compared with the effectiveness of a placebo. 300 single-sex calves in the 200 kg weight range, which had been purchased, were passed through a commercial cattle auction to ensure 5 adequate exposure to a potential infected herd for respiratory diseases and then loaded onto lorries and transported to the research site under conditions resembling commercial shipping practice.

The administration of interferon occurred at the cattle auction, 62 - 64 hours before arrival at the feedlot.

In a second study interferon was administered only on arrival of the animals at the feedlot.

In both test series, the number of sick animals (in percent), the number of sick days, and the rate of mortality (in percent) for both methods of administration (IH, IN) are compared with the control groups that 1 5 received no interferon.

The results are shown in the table below: Table 2: Experi Time of Number % Number 1 adminis Adminis of of sick mortal ment tration tration animals sick days1 ity 1 At cattle IM 107 44 2.02 1.9 auction IM 106 53 2.46 0.9 (62-64 hrs control 106 63 2.79 .7 before ari- rival at feedlot) 2 On arrival TM 100 29 1.48 0 at feedlot IM 99 28 1.61 0 control 99 53 1.70 0 1 total number of sick days/number of animals, over an observation period of 21 days.

In chess experiments it could be demons crated that rBoIFN-o:xl administered either intramuscularly or intranasally clearly reduced both the severity and the ineidenca of BED during the first three weeks of the experiment.

S. Field trials c-Enzootic Calf Pneumonia" The effect of rBoI.FM-axl against "Enzootic Calf PnsusioniaK was also investigated, under commercial conditions. 60-80 crossbred Simmental and Holstaiti dairy calves, bought from various sources, 2-3 weeks old and weighing 50 co 35 kg were brought to a cattle auction and then brought to the Ciba-Geigy research station in St. Aubin, Switzerland. Only clinically healthy calves were permitted for the trials. Animals demonstrating any signs of disease prior to the trial study were excluded.

After arrival the animals were weighed, individually tagged, and assigned by stratified random distribution (sex,, weight) to 2 replicate pens per treatment group in a closed stable.

The animals were fed with unmedicated milk substitute. Under these conditions a high proportion of the calves (70 to 90 %) developed spontaneous "BRD" within 3-15 days of arrival at the research station. Daily clinical examinations are conducted for 3 weeks, comprising the following parameters: Respiratory rate, coughing, nasal discharge, temperature, appetite and general behaviour (see p. 20).

Table 3: Disease incidence Experiment No.

Ho. of calves Treatment2 Dose (mg) Disease1 incidence (%) 1 58 Control/H20 16/19 (85) IM d 0 (lx) 0.5 11/18 (62) I FN d 0 (lx) .0 13/21 (62) 2 59 Control/H20 16/18 (90) IFN d 0 (lx) .0 16/20 (80) IFN d 0,7,14 (3x) .0 /21 (48) 3 78 Control 26/29 (89) IFN d 0,4 (2x) .0 /22 (90) IFN d 0 (lx) .0 18/27 (67) 1 Within the groups: number of sick animals/total number of animals 2 Intramuscular injection (2 sal of solution) into the neck muscles d Day(s) of treatment(s) relative to stabling (day 0) 19 Table 4: Mortality/sick days Experiment No. of Treatment: Dose No of 1 Wo. calves (mg) sick days 1 19 Control/H20 - 1.84 18 IFN d 0 (lx) 0.5 1.28 21 IFN d 0 (lx) .0 1.14 2 18 Control/H20 » 1.2 IFN d 0 (lx) .0 1.1 21 IFN d 0,7,14 (3x) .0 0.90 3 29 Control - 1.34 22 IFN d 0,4 (2x) .0 1.36 27 IFN d 0 (lx) .0 1.00 Within the groups: total number of sick days/number of animals, over an observation period of 21 days d Day(s) of treatment(s) relative to stabling (day 0) All test groups exhibited clearly improved clinical characteristics over the placebo controls. Th® incidence of disease and the number of sick days par animal were reduced markedly.

The administration of rBoIFM-Cjl weekly on days 0, 7 and 14 gave a reduction in the rata of mortality by up to 50 %.

Description of the clinical evaluation svscem Standardised clinical pvamination A distinction is made between 3 different categories, depending on the severity of the symptoms which occur with the normal condition being evaluated as 1 and the most severe as 3.

Respiratory rate 1 -60 2 >60 3 Cough no cough 1 infrequent, painless, mild 2 severe, painful, frequent and 3 respiratory distress Nasal discharge none 1 serous 2 mucopurulent 3 Auscultation normal 1 increased bronchial tones, 2 a few dry or moist rattles loud rattling noisas and 3 a lot of moist rattles and signs of pleuritis Body temperature 39.5°C 1 39.5-40.5°C 2 >40.5°C 3 The body temperature is taken 2x daily end the mean recorded.

Appetite normal 1 decreased 2 anorexia 3 Behaviour normal 1 moderately depressed 2 severely depressed, moribund 3 - 21 Interpretation of clinical score A specific coefficient is given to each of the parameters described in detail above, to determine an overall mean value (OMV). (■ Respiration rate X 3 Cough X i Nasal discharge X 2 Auscultation X 2 Body temperature X 3 Appetite X 3 Behaviour X 2 Total Total/16 - OMV Analysis of disease history can be obtained from the evolution of the overall mean value (OMV), and its area under the curve (AUG) and the 15 analysis of AUC and OMV. Comparison between individual treatments is made using covarianca analysis.

Claims (5)

1. 22 - PATENT CLAIMS " 1. The use of recombinant bovine <2-interferon for the preparation of & medicament for the single, intramuscular, prophylactic treatment of young cattle kept in close confinement and predisposed by stress, 5 chemical agents and psychological factors to bovine respiratory disease complex, for the prevention of this disease.
2. 2. The use according to claim 1, wherein the medicament to be prepared contains recombinant bovine cs-interferon in & single dose of from 0.5 ssg to 250 rag. 10
3. 3. The use according to claim 2, wherein the medicament to be prepared contains recombinant bovine cs-interferon in & single dose of from 1.0 mg to 50 mg.
4. 4. The use according to claim 3, wherein the medicament to be prepared contains recombinant bovine a-interferon in a single dose of from 3.0 mg 15 to 10 mg.
5. 5. Use according to claim 1, substantially as hereinbefore described. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS„ J