FRAGMENTS OF PRION PROTEINS

Abstract: Synthetic polypeptides having at least one antigenic site of a prion protein are disclosed together with methods for their use and manufacture and antibodies raised against such polypeptides. Diagnostic kits using the polypeptides and/or antibodies are also disclosed.

Description: FRAGMENTS OF PRION PROTEINS The present invention relates to synthetic polypeptides. In particular it relates to synthetic polypeptides which emulate the three-dimensional structures and/or electrostatic surfaces and/or other physical, chemical and structural properties of specific regions of proteins thought to be the involved in the molecular pathology of spoήgiforirt encephalopathies. It is of particular interest to the design of immunodiagnostics, vaccines and other medical, veterinary or scientific agents in relation to human, bovine and ovine spongiform encephalopathies. Spongiform encephalopathies are a group of degenerative neurological diseases. Examples have been found in a number of species including sheep (where it is known as scrapie) , cows (BSE) and humans (Creutzfeldt-Jakob disease (CJD) and kuru) (Review article, Taylor, D.M. Veterinary Record 125,413-415 (1989)). Similar conditions have also been found in the wild mink population and in captive kudus (a kind of antelope) and tigers. It has been variously reported that BSE can be transmitted under laboratory conditions to mice and pigs. This crossing of species barriers by the infective agent has led to increased concern that transfer to humans could occur. These diseases are characterised by a slow incubation time of four to five years after which the clinical symptoms of progressive degeneration of mental state, including aggressiveness and lack of coordination, appear. Post mortems reveal a characteristic pattern of vacuolation in brain tissue due to the destruction of neural cells, and the deposition of unusual protein fibres. Although the form of the disease found in sheep (scrapie) has been known for many years, spongiform encephalopathies have come to prominence within the last decade following the appearance of BSE in cattle farms. The incidence of BSE in the United Kingdom has increased markedly during this period and public concern over the possible transmission of the disease to humans has led to a collapse in the beef market. Thus for both veterinary and economic reasons, there is an urgent need for diagnostic agents to detect infection and for vaccines to prevent infection. It is believed that the causative agent of scrapie and its counterparts in other animals is a so-called "prion", that is an infective particle comprising protein only and no nucleic acid,, the presence of the latter being required in the case of a conventional virus. In scrapie, one particular protein (termed prion protein, PrP sc ) has been found to co-purify with infectivity and can produce a scrapie-like condition in brain cell cultures from other animals , such as hamsters> under laboratory conditions. PrP sc is the only known component of the characteristic protein fibres deposited in the brain tissue of scrapie-infeeted sheep. The term » prP sc " as used herein should be taken to refer not only to the specific Prion protein identified in sheep but also to those homologous proteins found in many other species which appear to undergo a structural modification as described hereinafter. The term "PrP c " shall be used in respect of the normal cellular counterpart to PrP sc . The major problem in the search for a specific diagnostic agent or synthetic vaccine against the scrapie agent PrP sc is that it is almost identical to the natural form of the protein PrP c . The natural function of this protein is not yet understood but the remarkably strong conservation of primary structure between homologous proteins from different species suggests that it has an essential structural or functional role within the organism. In spite of the almost identical form of these prions to the natural proteins, we have deduced synthetic peptide structures comprising at least one antigenic property, such as an epitopic site and these synthetic peptides may be used to produce diagnostic agents and vaccines. The responses of the B and T cells of the immune system are not specified by a global recognition of a whole p. -tein but rather by recognition of a small region of the protein surface known as epitopic site. Such sites may be formed by a continuous section of peptide chain or may be discontinuous, where separated sections of peptide chain are brought together at the protein surface due to folding of the chain. One aim in producing a synthetic peptide vaccine is to mimic the structure of a particular epitope and thereby cause a primary immune response leading to the production of memory B cells which will secrete antibodies on subsequent exposure to the parent protein so producing a greatly enhanced response to secondary infection. A similar mechanism via priming of the cytotoxic T cells to respond more vigorously to a particular antigen will also occur. However, problems exist with the application of traditional methods of vaccine production to this disease as it is believed that the molecular structure of the protein prion rather than nucleic acid sequence passes on infectivity in the prion. The usual method of viral vaccine production involves the inactivation of the virus in some way to destroy infectivity whilst preserving epitopic sites. Such techniques as heat treatment or serial passaging of the virus through a culture are used, but these approaches would not lead to a loss of infectivity of a prion unless conditions were such as to cause protein denaturation. If the conditions are severe enough to inactivate the prion protein then denaturation of the protein occurs and any epitopic sites are lost. Thus there is a major problem in trying to obtain antigenic but non-infective prion proteins by conventional routes. It is known, for example, that the scrapie agent in sheep is particularly resistant to chemical or physical inactivation (Hodgson, J. Bio/Technology 8 . 990 (1990)). In one aspect our invention provides a synthetic polypeptide having at least one antigenic site of a prion protein. Preferably the prion protein is of a form which only exists in nervous tissue of a mammal suffering from spongiform encephalopathy. We have found that prion proteins of the type mentioned above comprise six regions of interest, labelled A to F, and two related frame shift peptide sequences, viz:l) a repeating section in region E having undergone a nucleic acid coding sequence frame shift of +1 (FSa) and 2) the repeating section in region E having undergone a nucleic acid coding sequence frame shift of -1 (FSb) . With regard to region A, our invention provides a synthetic peptide sequence according to general formula ( I ) : X-(R.-Lys-His-R. -Ala-Gly-Ala-Ala-Ala-R j -Gly-Ala-Val- Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala-Met- Ser-(Arg-Pro-R 4 -R 5 )-Y CD wherein R 1 is an amino acid residue selected from Met, Leu and Phe; R 2 is either Met or Val; R 3 is Ala or is absent; R 4 and R 5 are independently an amino acid residue selected from Leu, lie and Met; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more additional amino acid residues. It will be apparent for example that the residues at the N-terminal of the sequence may be present as "R 2 "- or "His-R 2 -," or "Lys-His-R.,-" or "R.-Lys-His-R^. " Similarly, the preferable residues at the C-terminal may be present as "-Arg", or "-Arg-Pro," or "-Arg-Pro-R 4 , " or "-Arg-Pro-R 4 -R 5 ." Preferably, R 1 , if present, is Met, R 3 is Ala and R 5 , if present, is lie. Also, if R 2 is Met then R 4 , if present, is lie. Below are preferred sequences (Seq. I.D. No: 1 and Seq. I.D. No: 2) of formula I relating to bovine and ovine and to human prion proteins respectively: Seq. I.D. No: 1 X -(Met-Lys-His-Val)-Ala-Gly-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser-(Arg-Pro-Leu-Ile)-Y; ε -J Seq. I.D. No: 2 X-(Met-Lys-His-Met)-Ala-Gly-Ala-Ala-Al--Ala-Gly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser-(Arg-Pro-Ile-Ile)-Y. A particularly preferred sequence according to formula I is Seq. I.D. No: 51 Lys-His-Met-Ala-Gly-Ala-Ala-A ^ a-Ala- ly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser-Arg-Gly-Cys. Naturally, our invention encompasses significant sub-fragments of the sequence according to formula I above and preferred sub-fragments are: i) X-(His-R 2 -Ala-Gly)-Ala-Ala-Ala-R 3 -Gly-Ala-Val- - D - Val- (Gly-Gly-Leu-Gly) -Y and; ii) X- (Gly-Gly-Leu-Gly) -Gly-Tyr-Met-Leu-Gly-Ser- Ala-Met-Ser- (Arg-Pro-R 4 -R 5 ) -Y wherein R 2 , R 3 , R 4 , R 5 , X and Y are as defined for formula I and one or more residues in brackets may be absent or present as in formula I. It will be clear from the- foregoing that preferred sub-fragments relating to both bovines and ovines are Seq. I.DTNo: 3 i) X-(His-Val-Ala-Gly)-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-(Gly-Leu-Gly-Gly)-Y; and Seq. I.D. No: 4 ii) (Gly-Gly-Leu-Gly) -Gly-Tyr-Met-Leu-Gly-Ser- Ala-Met-Ser-(Arg-Pro-Leu-Ile) -Y. Similarly, preferred sub-fragments for humans are: Seq. I.D. No: 5 i) X-(His-Met-Ala-Gly)-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-(Gly-Leu-Gly-Gly) -Y; and Seq. I.D. No: 6 ii) X-(Gly-Gly-Leu-Gly)-Gly-Tyr-Met-Leu-Gly-Ser- Ala-Met-Ser-(Arg-Pro-Ile-Ile)-Y. - With regard to region B, our invention provides a synthetic peptide sequence according to general formula II: X-(Ser-Ala-Met-Ser) -Arg-Pro-R^-R g -His-Phe-Gly-R^ Asp-R 7 -Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-R g -Arg- (Tyr-Pro-Asn-Gln) -Y (II) wherein R 4 and R 5 are the same as in formula I; R 6 is either Asn or S.er ; R 7 is either Tyr or Trp; R 8 is an amino acid residue selected from His, Tyr and Asn; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more additional amino acid residues. Preferably in a sequence according to formula II, R 5 is lie, R 7 is Tyr and R 8 is His or Tyr. Below are preferred iquences of formula II relating to bovine, ovine and human prion proteins respectively: Seq. I.D. No: 7 X-(Ser-Ala-Met-Ser)-Arg-Pro-Leu-Ile-His-Phe-Gly-Ser- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-His-Arg- (Tyr-Pro-Asn-Gln)-Y; Seq. I.D. No: 8 X-(Ser-Ala-Met-Ser)-Arg-Pro-Leu-Ile-His-Phe-Gly-Asn- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-Tyr-Arg- (Tyr-Pro-Asn-Gln)-Y; and Seq. I.D. No: 9 X-(Ser-Ala-Met-Ser)-Arg-Pro-Ile-Ile-His-Phe-Gly-Ser- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-His-Arg- (Tyr-Pro-Asn-Gln)-Y. Particularly preferred sequences are selected from Seq. I.D. No: 42 Ser-Ala-Met-Ser-Arg-Pro-Leu-Ile-His-Phe-Gly- Asn-Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Gly-Cys; and Seq. I . D . No : 43 Ser-Ala-Met-Ser=-Arg-Pro-Leu-Ile-His-Phe-Gly- Ser-Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Gly-Cys . Again it will be apparent that our invention encompasses significant sub-fragments of the sequence according to Formula II and a preferred general sub- fragment has the sequence:- X-(Ser-Ala-Met-Ser)-Arg-Pro-R 4 -R 5 -His-Phe-Gly-R 6 - Asp-R 7 -Glu-Asp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met) -Y wherein R^ to R 7 , X and Y are as defined in formula II and one or more residues in brackets may be present or absent. Preferably, R 5 is lie and R 7 is Tyr. It will be appreciated that preferred sub-fragments relating to bovines, ovines and humans are respectively; Seq. I.D. No: 10 X-(Seir-Ala-Met-Ser) -Arg-Pro-Leu-Ile-His-Phe-Gly-Ser- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met) -Y; Seq. I.D. No: 11 X-(Ser-Ala-Met-Ser)-Arg-Pro-Leu-Ile-His-Phe-Gly-Asn- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met) -Y; and Seq. I.D. No: 12 X-(Ser-Ala-Met-Ser) -Arg-Pro-Ile-Ile-His-Phe-Gly-Ser- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met)-Y. Our invention provides in respect of region C a synthetic peptide sequence according to general formula III: X-(Asn-Met-R g -Arg)-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-R 9 -Asp-R 10 -Tyr-R. π -Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y ( III ) wherein R g is an amino acid residue selected from His, Tyr and Asn; R ς , is Val or Met; R 10 is an amino acid residue selected from Gin, Glu and Arg; R^ is Ser or Asn; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequenc and X and Y may each independently be absent or indeperr-.ntly be one or more additional amino acid residues. Preferably in a sequence according to formula III, R 8 is His cr Tyr and R is Ser. Below are preferred sequences of formula III relating to bovine, ovine and human prion proteins respectively: Seq. I.D. No: 13 X-(Asn-Met-His-Arg)-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-Val-Asp-Gln-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn) -Y; Seq. I.D. No: 14 X-(Asn-Met-Tyr-Arg)-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-Val-Asp-Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn) -Y; and Seq. I.D. No: 15 X-(Asn-Met-His-Arg)-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-Met-Asp-Glu-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn) -Y. Particularly preferred sequences are selected from Seq. I.D. No: 44 Asn-Met-Tyr-Arg-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg-Pro-Val- Asp-Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His-Gly-Cys; and Seq. I . D. No : 45 Asn-Met-His-Arg-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg-Pro-Val- Asp-Gln-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His-Gly-Cys . Significant sub-fragments of the sequence according to formula III form part of this invention and a preferred sub-fragment has the sequence: X-(Arg-Tyr-Pro-Asn) -Gln-Val-Tyr^-Tyr-Arg-Pro-F^-Asp- R^-Tyr-R^-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y. Preferred sub-fragments relating to bovines, ovines and humans are respectively: Seq. I.D. No: 16 X-(Arg-Tyr-Pro-Asn)-Gln-Val-Tyr-Tyr-Arg-Pro-Val-Asp- Gln-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- ' (Asp-Cys-Val-Asn)-Y; Seq. I.D. No: 17 X-(Arg-Tyr-Pro-Asn) -Gln-Val-Tyr-Tyr-Arg-Pro-Val-Asp- Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y; and Seq. I.D. No: 18 X-(Arg-Tyr-Pro-Asn)-Gln-Val-Tyr-Tyr-Arg-Pro-Met-Asp- Glu-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y. In respect of region D, our invention provides a synthetic peptide sequence according to general formula IV: X-(Tyr-Tyr-R l2 -R 13 -Arg) -R κ -R 15 -Ser-R l6 -R 17 -R l8 -Leu-Phe-Ser- Ser-Pro-Pro-Val-Ile-Leu-Leu-Ile-Ser-Phe-Leu-Ile-Phe- Leu-R 19 -Val-Gly-Y (IV) wherein R 12 is Asp or Gin; R 13 is Gly or absent; R 14 is Gly or Arg; R 15 is Ala or Ser; R 16 is Ser or absent; R 17 is an amino acid residue selected from Ala, Thr, Met and Val; R 18 is Val or lie; R 19 is lie or Met; one or more residues within brackets may be present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence and X and Y may each independently be absent or independently be one or more additional amino acid residues. Preferably in a sequence according to formula IV R 12 is Gin, R 13 is absent, R is Gly, R 16 is absent, R 17 is Val or Met and R 19 is lie. Preferred sequences of formula IV relating to bovine and ovine and to human prion proteins respectively are given below: Seq. I.D. No: 19 X-(Tyr-Tyr-Gln-Arg) -Gly-Ala-Ser-Val-Ile-Leu-Phe-Ser- Ser-Pro-Pro-Val-Ile-Leu-Leu-Ile-Ser-Phe-Leu-Ile-Phe- Leu-Ile-Val-Gly-Y; and Seq. I.D. No: 20 X-(Tyr-Tyr-Gln-Arg) -Gly-Ser-Ser-Met-Val-Leu-Phe-Ser-Ser- Pro-Pro-Val-Ile-Leu-Leu-Ile-Ser-Phe-Leu-Ile- Phe-Leu-Ile-Val-Gly-Y. Clearly, it will be recognised that the present invention includes with its ambit significant sub- fragments of the sequence according to formula IV and a preferred general sub-fragment has the sequence: X-(-R 14 -R 15 -Ser-R 16 -R 17 ) -R 18 -Leu-Phe-Ser-Ser-Pro-Pro-Val- lie- ( Leu-Leu-Ile-Ser) -Y Wherein R 14 to R 18 , X and Y are as defined in formula IV and one or more residues within brackets may be present or absent as in formula IV. It is preferred that in a sub-fragment as given above, R κ is Gly, R 16 is absent and R 17 is Val or Met. Below are preferred sub-fragments relating to bovines and ovines and to humans respectively: Seq. I.D. No: 21 X-(Gly-Ala-Ser-Val)Ile-Leu-Phe-Ser-Ser-Pro-Pro-Val- Ile-(Leu-Leu-Ile-Ser)-Y; and Seq. I.D. No: 22 X-(Gly-Ser-Ser-Met)-Val-Leu-Phe-Ser-Ser-Pro-Pro-Val- Ile-(Leu-Leu-Ile-Ser)-Y. Our invention provides in respect of Region E three synthetic polypeptide sequences according to general formulae Va, Vb and Vc: X-(Pro-Gly-Gly-R 20 )-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro-Pro- Gln-Gly-(Gly-R 21 -R 22 -Trp)-Y (Va) ; X-(Gly-Gly-R 21 -R 22 -Trp)-Gly-Gln-Pro-His-Gly-Gly-Gly- X-(Gly-Gly-Gly-Trp)-Gly-Gln-Gly-Gly-R 24 -R 25 -His-R 26 - Gln-Trp-Asn-Lys-Pro-R 27 -Lys-Pro-Lys-Thr-R 28 -R 29 -Lys (-His-R 3Q -Ala-Gly)-Y (Vc) Wherein R 20 , R 21 , R^ and R 24 are each independently either Gly or absent; 22 either Gly or Thr; R 25 is either Thr or Ser; R ? , is an amino acid reε:.αue selected from Gly, Ser and R 28 are each independently either Asn or Ser: is an amino acid residue selected from Met, Leu R 30 is either Val or Met; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more additional amino acid residues. With regard to formulae Va to Vc above, it is preferred that R 22 is Gly, R 23 is absent, R 26 is Gly or Ser, R 27 is Ser, R 28 is Asn and R 29 is Met. Preferred bovine sequences of prion proteins according to formulae Va to Vc are given below: Seq. I.D. No: 23 X-(Pro-Gly-Gly-Gly) -Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro-Pro- Gln-Gly-(Gly-Gly-Gly-Trp) -Y; Seq. I.D. No: 24 X-(Gly-Gly-Gly-Trp)-Gly-Gln-Pro-His-Gly-Gly-Gly-Trp- (Gly-Gln-Pro-His)-Y; and Seq. I.D. No: 25 X-(Gly-Gly-Gly-Trp)-Gly-Gln-Gly-Gly-Thr-His-Gly-Gln- Trp-Asn-Lys-Pro-Ser-Lys-Pro-Lys-Thr-Asn-Met-Lyε (-His-Val-Ala-Gly) -Y. Preferred sequences of formulae Va to Vc relating to ovine prion proteins are as follows: Seq. I.D. No: 26 X-(Pro-Gly-Gly-Gly) -Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro- ' Pro-Gln-Gly- (Gly-Gly-Gly-Trp) -Y ; Seq. I . D . No : 27 X- (Gly-Gly-Gly-Trp) -Gly-Gln-Pro-His-Gly-Gly- Gly-Trp-(Gly-Gln-Pro-His) -Y; and Seq. I.D. No: 28 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Gly-Gly-Ser-His- Ser-Gln-Trp-Asn-Lys-Pro-Ser-Lys-Pro-Lys-Thr- Asn-Met-Lys(-His-Val-Ala-Gly) -Y. Preferred sequences of formulae Va to Vc relating to human prion proteins are as follows: Seq. I.D. No: 29 X-Pro-Gly-Gly-Gly-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr-Pro- Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro-Pro- Gln-Gly-(Gly-Gly-Gly-Trp) -Y; Seq. I.D. No: 30 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Pro-His-Gly-Gly-Gly- Trp-(Gly-Gln-Pro-His) -Y; and Seq. I.D. No: 31 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Gly-Gly-Gly-Thr-His-Ser- Gln-Trp-Asn-Lys-Pro-Ser-Lys-Pro-Lys-Thr-Asn-Met-Lys (-His-Met-Ala-Gly) -Y. Particularly preferred sequences of formulae Va to Vc consist of: Seq. I.D. No: 49 Gly-Gly-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr-Pro-Gly-Gln- Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro- Pro-Gln-Gly-Gly-Gly-Cys; Seq. I.D. No: 46 Gly-Gln-Pro-Hiε-Gly-Gly-Gly-Trp-Gly-Gln-Pro-His-Gly-Gly- Gly-Trp-Gly-Gln-Pro-His-Gly-Gly-Gly-Trp-Gly-Cys ; and Seq. I . D . No : 47 Gly-Gln-Gly-Gly-Ser-His-Ser-Gln-Trp-Asn-Lys-Pro- Ser-Lys-Pro-Lys-Thr-Asn-Met-Lys-His-Val-Gly-Cys . We have noted that in the nucleic acid sequence corresponding to region E, it is possible for the repeating sequence of formula Vb to have undergone a frame shift of either +1 or -1. Such frame shifts give rise to altered sequences in region E of the prion protein and our invention provides a synthetic polypeptide having a sequence wherein a repeat in region E has undergone a -1 frame shift as given in formula VI: X-(R 31 -R 32 -Trp-R 33 )-Trp-Leu-Gly-R 34 -R 35 -R 36 -Trp-R 37 (Trp-Leu-Gly-R 38 )-Y (VI) Wherein R 31 and R 35 are each independently either Ala or Thr; R 32 and R 36 are each independently an amino acid residue selected from Ser, Pro and Thr; R 33 and R 37 are each independently either Trp or Arg; R 34 and R 38 are each independently an amino acid residue selected from Ala, Ser, Pro and Thr; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more, additional amino acid residues. With regard to -l frame shifts in respect of region E in bovines, it is preferred that R 31 is Ala, R 32 , R 34 , R 36 and R 38 are each independently either Ser or Pro, R 33 and R 37 are Arg and R 35 is Ala. It should be noted that preferred sequences for -1 frame shifts in region E of ovines differ in some respects to those given for bovineε and in a preferred ovine sequence R 31 , R 32 , R 33 , R 35 , R 36 and R 37 correspond to the definitiions given for formula VI above; and R 34 and R 38 are each independently selected from Ser, Pro and Thr. In a preferred human sequence according to formula VI R 31 , R 34 , R 35 and R 38 are each Ala, R 32 and R 36 are each independently either Ser or Pro and R 33 and R 37 are both Trp. As mentioned previously, the frame shift may be +1 in the repeat portion of region E and this gives rise to different amino acid sequences. Accordingly, our invention provides a synthetic polypeptide according to formula VII below which relates to a +1 frame shift in the repeat of region E: X-(R 39 -R 40 -Met-R 41 )-Val-Ala-Gly-R 42 -R 43 -R 44 -Met-R 45 - (Val-Ala-Gly-R 46 )-Y (VII) Wherein R 39 and R 43 are each independently either Ser or Asn; R 40 and R 44 are each independently an amino acid residue selected from Pro, Leu and His, R 41 and R 45 are each independently Val or Glu; R 42 and R 46 are each independently selected from Val, Ala, Asp and Gly; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more, additional amino acid residues. A preferred bovine sequence according to formula VII comprises R 39 and R 43 each being Ser, R 42 and R 46 each being independently either Val or Ala and R 44 being either Pro or Leu; with the other R groups being as defined in formula VII. A preferred sequence according to formula VII relating to ovines is the same as given in general formula VII except R 42 and R 46 are each independently selected from Val, Ala a- Asp. With regard to a ' preferred human sequence according to formula VII, R 39 and R 43 are Ser, R 40 and R 44 are each independently Pro or Leu, R 41 and R 45 are Val and R 42 and R 6 are each independently either Asp or Gly. Our invention also provides a synthetic peptide sequence relating to region F and having either the general formula Villa or Vlllb: X-(Asn-Phe-Val-Hiεj -Asp-Cys-Val-Asn-Ile-Thr-R 47 -Lys- R 48 -His-Thr-Val-R 49 -Thr-Thr-Thr-Lys-Gly-Glu-Asn- Phe-Thr-Glu- (Thr-Asp-R 5Q -Lys) -Y (Villa) X-(Met-Cyε-R 51 -Thr) -Gln-Tyr-R 52 -R 53 -Glu-Ser-Gln-Ala- Tyr-Tyr-R 54 -R 55 -Arg-(R 56 -R 57 -Ser-R 58 -R 59 ) -Y (Vlllb) Wherein R 47 is either lie or Val; R 48 and R 52 are each independently either Gin or Glu; R 49 is either Val or Thr; R 50 is either Val or lie; R 51 is an amino acid residue selected from lie, Thr and Val ; R 52 is Gin or Glu; R 53 is either Arg or Lys; R 54 is either Asp or Gin; . R 55 is Gly or is absent; R 56 is either Gly or Arg; . R 57 is either Ala or Ser; R 53 is Ser or absent; R 59 is an amino acid residue selected from Ala, Thr, Met and Val; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more, e.g. 3, additional amino acid residues. It is preferred in formula Villa that R 49 is Thr and in formula Vlllb that R 51 is lie, R 53 iε Arg, R 54 is Gin, R^ s is absent, R 56 is Gly, R 57 is Ala and R 58 is absent. Most preferred bovine, ovine and human sequences according to formulae Villa and Vlllb are given below in order: Seq. I.D. No: 32 X-(Asn-Phe-Val-His) -Asp-Cys-Val-Asn-Ile-Thr-Val-Lys- Glu-His-Thr-Val-Thr-Thr-Thr-Thr-Lyε-Gly-Glu-Asn- Phe-Thr-Glu-(Thr-Asp-Ile-Lys) -Y bovine (Villa) , and Seq. I.D. No: 33 X-(Met-Cys-Ile-Thr) -Gln-Tyr-Gln-Arg-Glu-Ser-Gln-Ala- Tyr-Tyr-Gln-Arg-(Gly-Ala-Ser-Val)-Y bovine (Vlllb) ; Seq. I.D. No: 34 X-(Asn-Phe-Val-His) -Asp-Cys-Val-Asn-Ile-Thr-Val-Lys- Gln-His-Thr-Val-Thr-Thr-Thr-Thr-Lys-Gly-Glu-Asn- Phe-Thr-Glu-(Thr-Asp-Ile-Lys) -Y ovine (Villa) , and Seq. I.D. No:35 X-(Met-Cys-Ile-Thr) -Gln-Tyr-Gln-Arg-Glu-Ser-Gln-Ala- Tyr-Tyr-Gln-Arg-(Gly-Ala-Ser-Val) -Y - ovine (Vlllb) ; Seq. I.D. No:36 X-(Asn-Phe-Val-His)-Asp-Cys-Val-Asn-Ile-Thr-Ile-Lys- Gln-His-Thr-Val-Thr-Thr-Thr-Thr-Lys-Gly-Glu-Asn- Phe-Thr-Glu-(Thr-Asp-Val-Lys)-Y human (Villa) , and Seq. I.D. No:37 X- (Met-Cys-Ile-Thr) -Gln-Ty- -Glu-Arg-Glu-Ser-Gln-Ala- Tyr-Tyr-Gln- Arg- (Giy-Ser-Ser-Met) -Y human (Vlllb) . Particularly preferred sequences according to formula Villa and Vlllb are selected from Seq. I.D. No: 50 Val-Asn-Ile-Thr-Val-Lys-Gln-His-Thr-Val-Thr-Thr-Thr-Thr- Lys-Gly-Glu-Asn-Phe-Thr-Glu-Gly-Cys; and Seq. I.D. No: 48 Cyε-Ile-Thr-Gln-Tyr-Gln-Arg-Glu- Ser-Gln-Ala-Tyr-Tyr-Gln-Arg. Synthetic polypeptides according to any one formulae I to Vlllb above without X and Y being present will of course be useful, for example, in the production of antibodies. However, when X or Y are present they may be any length but preferably less than 20 amino acids, more preferably less than 10, eg. 3 to 6. It will of course be appreciated that a sequence according to any one of formulae I to Vlllb may constitute a protein with X and Y being major portions of the protein with the antigenic εequence being for example, part of an exposed loop t a globular protein. It is preferred that if X or Y are present they are relatively short sequences, typically 1 to 3 residues long. In most instances X is preferably absent and Y is 1 or 2 residues long, e.g. -Cyε r -G -Cys. All the sequences herein are sta. .d -using the standard I.U.P.A.C. three-letter-code abbreviations for amino acid residues defined as follows: Gly-Glycine, Ala-Alanine, Val-Valine, Leu-Leucine, Ile-Isoleucine, Ser-Serine, Thr-Threonine, Asp-Aεpartic acid, Glu- Glutamic acid, Asn-Aεparagine, Gln-Glutamine, Lyε- Lysine, His-Histidine r Arg-Arginine, Phe-Phenylalanine, Tyr-Tyrosine, Trp-Tryptophan, Cys-Cysteine, Met- Methionine and Pro-Proline. Polypeptides according to the invention may be used to raise antibodies which will cross-react with prion proteins produced in a wide range of organisms. Our analyses have shown that since the conformational, topographic and electrostatic properties of polypeptides according to the invention are such that they are highly likely to elicit the production of antibodies which will cross-react with prion proteins from several or many organisms, further advantages may ariεe from combining several variant polypeptides in a larger polypeptide. Such a polypeptide may have the general formula (IX) : wherein F and G may each independently be a polypeptide or sub-fragment according to any one of Formulae I to Vlllb, L is a linking sequence, a, b and c are each independently 0 or 1 and m and n are each positive numbers e.g. between 1 and 10 inclusive. L is preferably a short, conformationally flexible section of polypeptide chain such as, for example and without limit (Seq. I.D. No: 38) Gly-Gly-Gly-Gly-Gly, (Seq. I.D. No: 39) Gly-Pro-Gly-Pro-Gly-Pro or (Seq. I.D. No: 40) Gly- Ser-Ala-Gly-Ser-Gly-Ala. It should be clear that each repeat may optionally have a different variant of a polypeptide according to the invention. It should be noted certain of the C-teminals correspond to N-terminals, particularly formula Va to formula Vb, formula Vc to formula I, formula I to formula II, formula II to formula III, formula III to formula Villa and formula Vlllb to formula IV. Advantage may be taken to -this correspondence when producing larger polypeptides according to formula IX. Linking sequences together with respective X and Y moieties may be omitted and residues in brackets may be εelected εo that either the regionε of correspondence are duplicated or some or all of the duplicated residues are omitted. In the latter case it will be seen that the C-terminal of one polypeptide merges with the N- terminal of the other polypeptide. Polyvalent determinant analogues as defined by Formula IX may be either what is referred to as pseudohomopolyvalent, wherein variants of eεsentially the same determinant analogue are repeated in a single polypeptide chain and/or heteropolyvalent, wherein distinct determinants are included in a single polypeptide. In addition, simple homopolyvalent polypeptide immunogens, which contain multiple copies of the same variant of one of the determinant analogues according to any one of formulae I to Vlllb, would also be expected to be effective, and are also included within the scope of the present invention. It. is to be understood that any antigenically significant subfragments and/or antigenically significant variants of the above-identified polypeptide sequences which retain the general form and function of the parent polypeptide are included within the scope of this invention. In particular, the substitution of any of the specific residues by residues having comparable conformational and/or physical properties, including substitution by rare (but naturally occurring, e.g. D-stereoisomers) or synthetic amino acid analogues, is included. For example, substitution of a residue by another in the same Set, as defined below, is included within the ambit of the invention; Set 1 - Ala, Val, Leu, lie, Phe, Tyr, Trp and Met; Set 2 - Ser, Thr, Asn and Gin; Set 3 - Asp and Glu; Set 4 - Lys, His and Arg; Set 5 - Asn and Asp; Set 6 - Glu and Gin; Set 7 - Gly, Ala, Pro, Ser and Thr. D-stereoisomers of all amino acid types, may be substituted, for example, D-Phe, D-Tyr and D-Trp. In preferred embodiments of the invention, X and Y if present may independently include one or more segments of protein sequence with the ability to act as a T-cell epitope. For example, segments of amino acid sequence of the general formula 1-2-3-4, where 1 is Gly or a charged amino acid (e.g. Lys, His, Arg, Asp or Glu) , 2 is a hydrophobic amino acid (e.g. lie, Leu, Val, Met, Tyr, Phe, Trp, Ala), 3 is- either a hydrophobic amino acid (as defined above) or an uncharged polar amino acid (e.g. Asn, Ser, Thr, Pro, Gin, Gly) , and 4 is a polar amino acid (e.g. Lys, Arg, His, Glu, Asp, Asn, Gin, Ser, Thr, Pro) , appear to act as T-cell epitopeε in at least some inεtances (Rothbard, J.B. & Taylor, W.R. (1988) . A sequence pattern in common to T-cell epitopes. The EMBO Journal≤rέl) •* 93-100) . Similarly segments can be of the sequence l'-2 '-3 *-4 '-5' , wherein 1 « is equivalent to 1 as defined earlier, 2' to 2, 3 1 and 4' to 3, andaf?' to 4 (ibid). Both forms are included within the scope of the present invention and one or more T-cell epitopes (preferably less than five) which may be of the type defined above or may be of other structure and which may be separated by spacer segments of any length or composition, preferably less than five amino acid residues in length and comprising for example residues selected from Gly, Ala, Pro, Asn, Thr, Ser or polyfunctional linkers such as non-α amino acids. It is possible for a C- or N-terminal. linker to represent a complete protein, thus obviating the possible need for conjugation to a carrier protein. Also included within the scope of this invention are derivatives of the polypeptides according to any one formulae I to Vlllb in which X or Y are or include a "retro-inverso" amino acid, i.e. a bifunctional amine having a functional group corresponding to an amino acid. For example an analogue according to the invention and containing a retro-inverso amino acid may have the formula : R I Al - N - C - N - A2 I I I H H H where R is any functional group, e.g. a glycine side chain, and Al and A2 are preferably each a copy of one of the analogues defined herein (but not necessarily the εame) attached by itε N- or C-terminal end. T-cell epitopes may optionally be included as discussed earlier. Retro-inverso modification of peptides involves the reversal of one or more peptide bonds to create analogues more resistant than the original molecule to enzymatic degradation and offer one convenient route to the generation of branched immunogens which contain a high concentration of epitope for a medium to large immunσgen. The use of these compounds in large-scale solution synthesis of retro-inverso analogues of short- chain biologically active peptides has great potential. Peptides according to the invention may be synthesised by standard peptide syntheεis techniques, for example using either standard 9-fluorenyl- ethoxycarbonyl (F-Moc) chemistry (see, for example, Atherton, E. and Sheppard, R. C. (1985) J. Chem. Soc. Chem. Comm. 165) or standard butyloxycarbonate (T-Boc) chemistry although it is noted that, more recently, the fluσrenylmethoxycarbonyl (Fmoc)/tert-butyl system, developed by Sheppard et al has found increasingly wide application (Sheppard, R.C.1986 Science Tools, The LKB Journal 33, 9) . The correctness of the structure and the level of purity, which will normally be in excess of 85%, should be carefully checked, and particular attention be given to the correctness of internal disulphide bridging arrangements when present. Various chromatographic analyseε, including high performance liquid chromatography, and spectrographic analyses, including Raman spectroscopy, may for example be employed for this purpose. It is to be underεtood that the polypeptideε according to the invention may be synthesised by any conventional method, either directly using manual or automated peptide synthesis techniques as mentioned above, or indirectly by RNA or DNA synthesis and conventional techniques of molecular biology and genetic engineering. Such techniques may be used to produce hybrid proteins containing one or more of the polypeptides inserted into another polypeptide εequence. Another aεpect of the preεent invention therefore provides a DNA molecule coding for at least one synthetic polypeptide according to the invention, preferably incorporated into a suitable expression vector replicable in microorganisms or in mammalian cells. The DNA may also be part of the DNA sequence for a longer product e.g. the polypeptides may be expressed as parts of other proteins into which they have been inserted by genetic engineering. One practical guide to such techniques is "Molecular cloning: a laboratory manual" by Sambrook, J. , Fritsch, E.F. and Maniatis, T. (2nd Edition, 1989) . It should be noted that analogues incorporating retro-inverso amino acid derivatives cannot be made directly using a recombinant DNA system. However, the basic analogues can, and they can then be purified and chemically linked to the retro-inverso amino-acids using standard peptide/organic chemistry. A practical and * convenient novel procedure for the solid-phase synthesis on polyamide-type resin of retro-inverso peptides has been described recently [Gazerro, H. , Pinori, M. & Verdini, A.S. (1990) . A new general procedure for the solid-phase synthesis of retro-inverso peptides. In "Innovation and Perspectives in Solid Phase Synthesis" Ed. Roger Epton. SPCC (UK) Ltd, Birmingham, UK] . The polypeptides are optionally linked to a carrier molecule, either through chemical groups within the polypeptides themselves or through additional amino acids added at either the c- or N-terminus, and which may be separated from the polypeptide themselv - or surrounded by one or more additional amino acids, in order to render them optimal for their immunoloσical function. Many linkages are suitable and incluue for example use of the side chains of Tyr, Cys and Lys residues. Suitable carriers include, for example, purified protein derivative of tubercul n (PPD), tetanus toxoid (TT) , cholera toxin and its B εubunit, ovalbu in, bovine serum albumin (BSA) , soybean trypsin inhibitor (f I) , ^ramyl dipeptide (MDP) and analogues thereof, c hthc toxoid (DPT) , keyhole limpet haemocyanin (_. M) <_ 3raun's lipoproteir although other suitable carrier... will be readily apparent to the skilled person. For example, multiple antigen peptides may be used εuch as those comprising a polylysyl core, e.g. heptalysyl, bearing reactive amine termini. Polypeptide antigens according to the invention may be reacted with, or synthesised on, the amino termini and different polypeptide antigens may be reacted with the same core or carrier. When using PPD as a carrier for polypeptides according to the invention, a higher titre of antibodies is achieved if the recipient of the polypeptide-PPD conjugate is already tuberculin sensitive, e.g. by virtue of earlier BCG vaccination. In the case of a human vaccine it is worth noting that in the UK and many other countries the population is routinely offered BCG vaccination and is therefore largely PPD-sensitive. Hence PPD is expected to be a preferred carrier for use in such countries. The mode of coupling the polypeptide to the carrier will depend on the nature of the materials to be coupled. For example, a lysine residue in the carrier may be coupled to a C-terminal or other cysteine residue in a polypeptide by treatment with N-γ -maleimidobutyryloxy-succinimide (Kitagawa, T. & Ackawa, T. (1976) J. Biochem. -79 . , 233) . Alternatively, a lysine residue in the carrier may be conjugated to a glutamic or aspactic acid residue in the peptide uεing isobutylchlorofor ate (Thorell, J.I. De Larson, S.M. (1978) Radioimmunoassay and related techniques: Methodology and clinical applications, p.288) . Other coupling reactions and reagents have been described in the literature. The polypeptides, either alone or linked to a carrier molecule, may be administered by any route (eg parenteral, nasal, oral, rectal, intra-vaginal) , with or without the use of conventional adjuvants (such as aluminium hydroxide or Freund's complete or incomplete adjuvants) and/or other immunopotentiating agents. The invention also includes formulation of polypeptides according to the invention in slow-release forms, such as a sub-dermal implant or depot comprising, for example, liposomes (Allison, A.C. & Gregoriadis, G. (1974) Nature (London) 252. 252) or biodegradable microcapsules manufactured from co-polymers of lactic acid and glycolic acids (Gresser, J. D. and Sanderson, J. E. (1984) in "Biopolymer Controlled Release Systems" pp 127-138, Ed. D. L. Wise). Polypeptides according to the invention may be used either alone or linked to an appropriate carrier, as: (a) As ligands in assays of, for example, serum from patients or animals; (b) Peptide vaccines, for use in prophylaxis; (c) As quality control agents in testing, for example, binding levels of antibodies raised against the polypeptides; (d) As antigenic agents for the generation of monoclonal or polyclonal antibodies by immunisation of an appropriate animal, such antibodies being of use for (i) the scientific study of prion proteins, (ii) as diagnostic agents, e.g. as part of immunohistochemical reagents, (iii) for the passive immunisation of animals or patients, either as a treatment for encephalophathies or in combination with other agents, (iv) as a means of targeting other agents to regions comprising prion proteins, such agents either being linked covalently or otherwiεe aεsociated, e.g. as in liposomeε containing such agents and incorporating antibodies raised against any of the antigenic polypeptides and (v) for uεe as immunogens to raise anti-idiotype antibodies; such anti- idiotype antibodies also form part of this invention. The invention further provides for genetically engineered forms or sub-components, especially V H regions, of antibodies raised against the polypeptides, and of ovinised, bovinised, or humanised forms of antibodieε initially raised against the polypeptides in other animals, using techniques described in the literature; and (e) The treatment of encephalopathies, either by displacing the binding of prion proteins to human or animal cells or by disturbing the three-dimensional organisation of the protein in vivo; as well as aiding the scientific study of prion proteins in vitro. In respect of detection and diagnosiε, of prion proteins or antibodies against prion proteinε, the skilled person will be aware of a variety of immunoasεay techniqueε known in the art, inter alia, εandwich assay, competitive and non-competitive assayε and the uεe of direct and indirect labelling. A further aspect of the invention provides a kit for detecting prion proteins or antibodieε againεt prion proteins which compriεes at least one synthetic polypeptide according to the invention. The preparation of polyclonal or monoclonal antibodies, humanised forms of such antibodies (see, for example, Thompson K. M. et al (1986) Immunology .58, 157- 160) , single domain antibodies (see, for example, Ward, E. S., Gusεow, D. , Griffiths, A. D. , Jones, P. and Winter, G. (1989) Nature 341, 544-546) , and antibodies which might cross the .blood-brain barrier, which bind specifically to a synthetic polypeptide according to the present invention, may be carried out by conventional means and such antibodieε are considered to form part of this invention. Antibodies according to the invention are, inter alia, of use in a method of diagnosing mammalian encephalopathieε which comprises incubating a sample of tisεue or body fluid- of mammal with an amount of antibody aε deεcribed herein and determining whether, and if desired the extent to which and/or rate at which, cross-reaction between said sample and said antibody occurs. Diagnostic kits which contain at least one of said antibodieε also form part of this invention. A further aεpect of the invention provideε synthetic polypeptides for uεe in therapy or prophylaxis of mammalian encephalopathieε and/or stimulating the mammalian immune system and/or blocking the cellular binding or aggregation of the prion proteins and for the preparation of medicaments εuitable for εuch uses. Also included are pharmaceutical compositionε containing, as active ingredient, at least one polypeptide or polypeptide-carrier conjugate as described herein in association with one or more pharmaceutically acceptable adjuvants, carriers and/or excipients. The compositions may be formulated for oral, rectal, nasal or especially parenteral administration (including intra-CNS administration) . The invention further provides a method of therapy or prophylaxis of mammalian encephalopathies and/or of stimulating the mammalian immune system and/or of blocking the cellular binding or aggregation of the prion proteins, which comprises administering an amount of a polypeptide as hereinbefore defined, either in isolation or in combination with other agents for the treatment of encephalopathies. Discrimination between natural PrP c and PrP sc is highly desired since PrP c is found in normal subjects and both PrP c and prP sc are found in a diseased subject. We have found that peptide sequences according to the invention, preferably those relating to regions A, B and C, and significant sub-fragments thereof may be used to discriminate between natural PrP c and infective PrP sc . Also, antibodies raised against these peptide εequences and sub-fragments and the nucleotide sequenceε which code for εuch peptide sequences and sub-fragmentε may also be used to diεcriminate between PrP c and PrP sc . Accordingly, the invention provides a method of discriminating between PrP c and PrP sc in which a sample is contacted with a substance selected from peptide sequences according to the invention, preferably those relating to regions A, B and C, and significant sub- fragments thereof, antibodies raised against said sequenceε and sub-fragmentε and the presence or absence of PrP sc is determined. In some instances discrimination may be enhanced by pretreatment of the sample, for example by pre-digestion with enzymes e.g. proteinase K, or denaturation by strong alkali e.g. 6M guanidine hydrochloride or by a combination of such treatments. It will be preferable to use the peptide εequenceε, antibodies and nucleotide sequences which relate to the specific subject under test, e.g. bovine sequences and antibodies for cattle, ovine sequenceε and antibodieε for sheep. It may be advantageouε to immuniεe with a cocktail containing (i) a given analogue conjugated to more than one type of carrier molecule, and/or (ii) more than one kind of analogue conjugated to the εame carrier molecule. Moreover, any of the peptide analogueε, their conjugates, and cocktailε thereof may be adminiεtered in any suitable adjuvant or delivery system, and more than one adjuvant or delivery system may be combined to form - ->. ( 0, — a so-called "super-cocktail". Preferred adjuvants and delivery systems include aluminium hydroxide (alum) , liposomes, micelles, niosomes, ISCOMS, Brauns lipoprotein and whole-cell or components of microbial animal vaccines. Example 1 A preferred bovine form of formula II (Seq. I.D. No: 41) Ala-Met-Ser-Arg-Pro-Leu-Ile-His-Phe-Gly-Ser-Asp- Tyr-Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-His-Arg-Gly-Cys (related to Seq. I.D. No: 7) in which the C-terminal Y extension is Gly-Cys according to the invention is synthesised uεing εtandard εolid-phaεe Fmoc methodologieε. The peptide iε cleaved from the resin in the presence of trifluroacetic acid and subsequent purification is achieved by gel filtration, ion exhange chromatography and reverse phase high performance liquid chromatography. The peptide is conjugated to a variety of carriers by MBS (m-Maleimido-benzoyl-N-hydroxy succinimide ester) , a well-known hetero-bifunctional reagent.' Examples of carriers include KLH, BSA and TT which have been εhown to provide neceεsary immunopotentiating properties to B cell epitopes. The peptide carrier conjugates are emulsified in Freund's Complete Adjuvant and are administered intramuscularly to mice. Subsequent booster injections are given in Freund's Incomplete Adjuvant. The enεuing serum antibody response is monitored throughout the immunisation schedule by enzyme immunoassay (ELISA) using immobilised antigen (formula II) , coupled to BSA, the serum sample under test, and an enzyme-labelled anti-mouse antibody. In this example, use of carriers, adjuvants and delivery systems and booster injections are effected in order to determine an optimal protocol for producing anti-formula II antibodies. Example 2 Antibodieε to formula II are used as diagnoεtic reagents for assaying.the presence of prion protein in serum, in "cell carriers" in serum and in tissue biopsies of injected animal species. A direct enzyme immunoassay (ELISA) can detect the presence of extracted prion protein by its immobilisation onto a solid substrate. Reaction of mouse antisera raised to formula II with native prion protein is detected with an enzyme-labelled anti-mouse antiserum. The reaction is quantified by addition of a suitable substrate and reading the optical density of the colour produced. Furthermore, immunohistochemical diagnosis of prion proteins in tissue biopεieε can be performed by reacting anti-formula II antibodieε with paraffin wax embedded or frozen tissue. Reactions can be detected using a standard indirect immunoperoxidase technique. Example 3 MATERIALS AND METHODS Peptide Synthesis The following peptides were syntheεiεed using standard solid-phase Fmoc methodologies. Peptide II: (Seq. I.D. No: 42) Ser-Ala-Met-Ser-Arg-Pro-Leu-Ile-His-Phe-Gly- Asn-Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Gly-Cyε (A preferred ovine εub-fragment of formula II) . Peptide BII: (Seq. I.D. No: 43) Ser-Ala-Met-Ser-Arg-Pro-Leu-Ile-His-Phe-Gly- Ser-Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Gly-Cys (A preferred bovine sub-fragment of formula II) . Peptide III: (S&q. I.D. No: 44) Asn-Met-Tyr-Arg-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg-Pro-Val- Asp-Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His-Gly-Cys (A preferred ovine sequence of formula III (p8, In . 30-32). Peptide- Bill: (Seq. I.D. No: 45) Asn-Met-His-Arg-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg-Pro-Val- Asp-Gln-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His-Gly-Cys (A preferred bovine sequence of formula III (p8, In 26-28) . Peptide Vb : (Seq . I . D . No : 46 ) Gly-Gln-Pro-His-Gly-G-ly-Gly-Trp-Gly-Gln-Pro-His-Gly-Gly- Gly-Trp-Gly-Gln-Pro-His-Gly-Gly-Gly-Trp-Gly-Cys (A preferred ovine/bovine sequence of formula Vb) . Peptide Vc: (Seq .D. No: Gly-Gln-Gly- -Ser-Hi. :r-Gln-Trp-Asn-Lyε-Pro- f r-Lys-Pro-j_,ys-Thr-As ^t-Lys-His-Val-Gly-Cys (A preferred ovine sequence of formula Vc) . Peptide Vlllb: (Seq. I.D. No: 48) Cys-Ile-Thr-Gln-Tyr-Gln-Arg-Glu- Ser-Gln-Ala-Tyr-Tyr-Gln-Arg (A preferred ovine/bovir sequence of formula Vlllb) Peptide Va: (Seq. I.D. No: 49) Gly-Gly-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro- Pro-Gln-Gly-Gly-Gly-Cyε Peptide Villa: (Seq. I.D. No: 50) Val-Asn-Ile-Thr-Val-Lys-Gln-Hip-Thr-Val-Thr-Thr-Thr-Thr- Lys-Gly-Glu-Asn-Phe- r-Glu-Gly-Cys (A preferred ovine sequence of formula Villa) . Peptide I: (Seq. I.D. No: 51) Lys-His-Met-Ala-Gly-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser-Arg-Gly-Cys. Peptides I, II, BII, III, Bill, Va, Vb, Vc and Villa were synthesiεed with the C-terminal extension according to the invention. The peptides were cleaved from the resin in the presence of trifluoroacetic acid and subsequent purification was achieved by reverse phase high performance liquid chromatography. All peptides had a purity of 85% or more. Conjugation of peptides to ovalbumin Peptides were conjugated through their C-terminal (peptides II, BII, III, Bill, Vb and Vc) or N-terminal (peptide Vlllb) Cys residues. Peptides were disεolved in dimethyl εulphoxide (DMSO) to a concentration of 10 mg/ml. Preactivated ovalbumin (Pierce, Imject Kit) waε resuspended in 1 ml of distilled water, and equal volumes of preactivated ovalbumin and peptide were mixed and the solution allowed to stand at room temperature for 3 hours. The conjugate was dialysed overnight against phosphate buffered saline (PBS) to remove the DMSO and unconjugated peptide. The extent of conjugation was determined by measuring the free-thiol content uεing an Ellman'ε assay and by monitoring the increase in the molecular mass of the conjugate by SDS-PAGE (sodium dodecyl sulphate- polyacrylamide gel electrophoresis) . Generation of rabbit antisera. Antiserum was raised against each of the peptide conjugates in two female New Zealand White rabbits. Each rabbit received an amount of conjugate equivalent to 40 μg of peptide for both the primary inoculation -and the boosters. Rabbits were injected as follows: Day 0: Conjugate in Freund's Complete Adjuvant (1:1, v/v) intramuscularly. Day 21: Conjugate in Freund's Incomplete Adjuvant (1:1, v/v) intramuscularly. Day 31: Conjugate on its own intraperitoneally. Animals were bled on day 41, and the sera assayed for anti- peptide antibody by ELISA (using free peptide as the coating antigen) . The sera were also used in immunoblot and dot blot asεayε to see if they could recognise proteins from the brain homogenates. Preparation of brain homocrenates Scrapie-free brain material was obtained from a flock of New Zealand sheep in quarantine. Scrapie-infected brain material was obtained from a Department of Agriculture and had been histopathalogically diagnosed as being εcrapie infected. BSE-infected brain material waε obtained via a government Agriculture Department and had been hiεtopathalogically certified as being BSE infected. BSE-free material was obtained through a private source. Ha27-30 is brain material obtained from an inbred hamster scrapie model, which has been shown to contain a high level of the scrapie-infective agent. It was used as a positive control. Small samples of infected and uninfected brain were weighed and 10% (w/v) homogenates made up in 10% (v/v) solution of Sarkosyl in.25 mM Tris-HCl pH 7.4 (homogenisation buffer). The homogenate was incubated at 4°C for 30 minε and then spun at 6000 x g for 30 mins. The supernatant was collected and the protein content determined using the BCA protein assay kit (Pierce) . The protein concentration was adjusted to 3 mg/ml using homogenisation buffer. ELISA (Enzyme-linked immunosorbent assay) A 8 μM solution of free peptide in PBS waε used as the coating antigen. Microtitre plates were coated by adding 50 μl of the antigen concentration to each well and then incubating for 1 hour at 37°C to allow binding to occur. Each well was washed 5 times, for 2 minutes, with 300 μl of PBS containing 0.05% Tween 20. After washing, the plates were blocked by incubating for 1 hour at 37°C with PBS containing 0.3% Tween 20 and 3% non-fat milk. An aliquot of 50 μl of primary antibody (i.e. antisera) diluted in PBS was added to the appropriate wells and the plates incubated for 1 hour at 37°C. Plates were waεhed aε before, and then incubated with Horεeradiεh peroxidase conjugated swine anti-rabbit immunoglobulin (anti Ig/HRP) at a dilution of 1:1000 in PBS for 1 hour at 37°C. The plates were washed and 50 μl of OPD (O-phenylenediamine dihydrochloride substrate (10 mg/ml) in citrate buffer) added to each well and the reaction allowed to proceed at room temperature for 10 minutes, before being stopped by the addition of sulphuric acid. The absorbence of each well was measured at 492 ' ran using an ELISA plate reader. The titres were recorded as the dilutions which gave a positive optical density (OD) reading at least 3 times that of the background. The background was taken as the OD readings from wells which had not been coated with antigen. Dot blot detection of PrP in brain homoσenateε The brain homogenateε prepared as described earlier were diluted 10-fold in PBS, and 100 μl of homogenates (containing 30 μg total protein) were applied to nitrocellulose filters using BRL 96 well vacuum manifold. The filters were dried for 1 hour at room temperature. The filters were then either wet with TBST (10 mM Tris-HCl pH7.4, 150 mM NaCl, 0.05% Tween 20) and PrP detected as described in the immunoblots, or the protein sample further treated. This further treatment of the εample included digestion of the protein on the filter uεing 100 μg/ml proteinase K in TBST for 90 minutes at room temperature. The proteinase K was inactivated by the addition of PMSF (phenylmethylsulphσnyl fluoride) to a concentration of 5 mM in TBST. After protein digestion, some samples were also denatured by incubating the filters in 6M guanidine HCl containing 5 mM PMSF for 10 minutes. The guanidine was removed by 3 washes with TBST prior to incubation with the primary antibody. Immunoblots. (Western Blots] SDS-PAGE was performed on the brain homogenateε, prepared aε described previously, using standard techniques. The samples within the gel were transferred onto nitrocellulose in a Biorad transblot using Towbin Buffer (25 mM Tris, 190 mM glycine and 0.1% SDS) at 70 mA overnight. The nitrocellulose filter was blocked with 5% non-fat milk for 30 minutes at room temperature. The primary antibody (i.e. antisera) diluted in TBST was applied for 3 hours at room temperature, the filter washed 3 times for 10 minutes in TBST and the filter incubated for 2 hours at room temperature with the alkaline phosphatase-conjugated swine anti-rabbit immunoglobulin diluted at a dilution of 1:2000. After washing, the protein bandε were detected using the NBT/BCIP (nitro-blue tetrazσlium; 5-bromo-4-chloro-3- indolyl phosphate) substrate (Boehringer Mannheim) . RESULTS 1) Antibody titres: Good antibody titres to the peptides were obtained in all cases, though the level varied " enormously. The peptide which gave the highest titre, also gave the best results in the dot blots. 2) Dot Blot Data: Uninfected tissue would be expected to contain only normal prion protein (PrP c ) . Infected tissue would be expected to contain both the normal and the diseased (PrP sc ) forms of PrP. PrP c has a molecular weight of approximately 33-35 kD. PrP sc has a molecular weight of approximately 27-30 kD and is misεing an N-terminal segment that is present in the PrP c form. . Otherwise, the amino acid sequence of PrP sc is exactly the same aε that of PrP c . Probably the most significant characteristic of PrP sc is resistance to enzyme degradation with proteinase K, a non-specific protein-digesting enzyme. When a protein sample is treated with proteinase K any PrP c should be completely digested. Therefore, in a sample containing only PrP c , no PrP of any form will remain after proteinaεe K treatment. However, in a εample containing PrP c and PrP sc (i.e. a diseased sample) , PrP sc will remain after treatment. There are antibodies currently available which recognise PrP sc , but they only recognise the denatured protein. Therefore after proteinase K treatment, samples in the dot blot test were treated with guanidine HC1, a denaturing agent, so that such antibodies could be used to detect PrP sc . The data are given in Tables I-V. Peptide II: Good titres. Dot blots appear to indicate that some discrimination is occurring. Negative results were obtained from the Western blots. Peptide III: Reasonable titres. Possibly there is recognition of a non¬ specific (perhaps non-protein) component in the proteinase K and guanidine treated samples. Negative results were obtained from the Western blots. Peptide Vb: Good titres. Although it appears that there might be some discrimination occurring, the Vb peptide in fact occurs within the N-terminal region that is missing in PrP sc . One would therefore not expect to see any recognition in the infected material treated with proteinase K and guanidine. However, one possible explanation is that the PrP c present in the infected material has not been completely digested by the proteinase K. Negative results were obtained from the Western blotε. Peptide Vc: Excellent titres. Theεe reεults are exactly as expected. As mentioned previously, antibodies which recognise PrP sc generally only recognise the protein in its denatured state. Infected and uninfected εamples, as well as containing prP sc and/or PrP c in their "native" states, will also contain both PrP forms in various stages of denaturation due to natural protein turnover within cells. For this reaεon, antibodies would be expected to detect all three untreated samples. Howevei proteinase K treatment will digest FrP c and any partialT- denatured PrP sc leading to a loεs of antibody recogniti. n all samples (assuming the antibod; ..nly recognises de:...ured PrP) . The addition of guanidine should restore antibody recognition in material which had originally contained PrP sc . Western blots showed up the expected protein bands at the correct molecular weights. Peptide Vlllb: Reasonable titre. There may be recognition of a non¬ specific component. Negative results were obtained form the Western blots. Peptides BII & BII: The titres are reasonable and there are strong positive results from untreated normal and infected bovine brain ■material. In summary, good anti-peptide titres obtained in all cases, the Western blots only worked well in the case of peptide Vc, which also gave the highest titre and the dot blots show that there is some discrimination occurring between PrP c and PrP sc with peptide Vc. Data from peptide II also suggests that discrimination is occurring. Table I: Results from ovine peptide εeσuences - 41 - Table II: Results from ovine peptide sequences able III: Results from ovine bovine e tide se uences Table IV: Resultε from ovine/bovine peptide εeσuences Table V: Results from bovine peptide sequences SEQUENCE LISTING Number of Sequences 51 (1) Information for Seq. I.D. No: 1 (i) Characterisation of εequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 1 Met Lyε Hiε Val Ala Gly Ala Ala Ala Ala Gly Ala Val Val Gly Gly 1 5 10 . 15 Leu Gly Gly Tyr Met Leu Gly Ser Ala Met Ser Arg Pro Leu lie 20 25 30 (2) Information for Seq. I.D. No: 2 (i) Characteriεation of εequence: (A) Length: 31 Amino acidε (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Deεcription of sequence: Seq. I.D. No: 2 Met Lys His Met Ala Gly Ala Ala Ala Ala Gly Ala Val Val Gly Gly 1 5 10 15 Leu Gly Gly Tyr Met Leu Gly Ser Ala Met Ser Arg Pro lie lie 20 25 30 (3) Information for Seq. I.D. No: 3 (i) Characterisation of sequence: (A) Length: 17 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 3 His Val Ala Gly Ala Ala Ala Ala Gly Ala Val Val Gly Gly Leu Gl 1 5 10 15 Gly (4) Information for Seq. I.D. No: 4 (i) Characterisation of sequence: (A) Length: 17 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 4 Gly Gly Leu Gly Gly Tyr Met Leu Gly Ser Ala Met Ser Arg Pro Le 1 5 10 15 lie (5) Information for Seq. I.D. No: 5 (i) Characterisation of sequence: (A) Length: 17 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 5 His Met Ala Gly Ala Ala Ala Ala Gly Ala Val Val Gly Gly Leu Gl 1 5 10 15 Gly (6) Information for Seq. I.D. No: 6 (i) Characterisation of sequence: (A) Length: 17 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 6 Gly Gly Leu Gly Gly Tyr Met Leu Gly Ser Ala Met Ser Arg Pro lie 1 5 10 15 He (7) Information for Seq. I.D. No: 7 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 7 Ser Ala Met Ser Arg Pro Leu He His Phe Gly Ser Aεp Tyr Glu Asp 1 5 10 15 Arg Tyr Tyr Arg Glu Asn Met His Arg Tyr Pro Asn Gin 20 25 (8) Information for Seq. I.D. No: 8 (i) Characterisation of εequence: (A) Length: 29 Amino acidε (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 8 Ser Ala Met Ser Arg Pro Leu Tie His Phe Gly Asn Asp Tyr Glu Asp 1 " 5 10 15 Arg Tyr Tyr Arg Glu Asn Met Tyr Arg Tyr Pro Asn Gin 20 25 (9) Information for Seq. I.D. No: 9 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type:. Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 9 Ser Ala Met Ser Arg Pro He He His Phe Gly Ser Asp Tyr Glu As 1 5 10 15 Arg Tyr Tyr Arg Glu Asn Met His Arg Tyr Pro Asn Gin 20 25 (10) Information for Seq. I.D. No: 10 (i) Characterisation of sequence: (A) Length: 23 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 10 Ser Ala Met Ser Arg Pro Leu He His Phe Gly Ser Asp Tyr Glu As 1 5 10 15 Arg Tyr Tyr Arg Glu Aεn Met 20 (11) Information for Seq. I.D. No: 11 (i) Characterisation of sequence: (A) Length: 23 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Typ.-. of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 11 Ser Ala Met Ser Arg Pro Leu He His Phe Gly Asn Asp Tyr Glu As 1 5 10 15 Arg Tyr Tyr Arg Glu Asn Met 20 (12) Information for Seq. I.D. No: 12 (i) Characterisation of sequence: (A) Length: 23 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 12 Ser Ala Met Ser Arg Pro He He His Phe Gly Ser Asp Tyr Glu Asp 1 5 10 15 Arg Tyr Tyr Arg Glu Asn Met 20 (13) Information for Seq. I.D. No: 13 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 13 Asn Met His Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Val Asp Gin 1 5 10 15 Tyr Ser Asn Gin Asn Asn Phe Val His Aεp Cys Val Asn 20 25 (14) Information for Seq. I.D. No: 14 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 14 Asn Met Tyr Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Val Asp Arg 1 5 10 15 Tyr Ser Asn Gin Asn Asn Phe Val His Aεp Cys Val Asn 20 25 (15) Information for Seq. I.D. No: 15 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type:. Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 15 Asn Met His Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Met Asp Gl 1 5 10 15 Tyr Ser Asn Gin Asn Asn Phe Val His Asp Cys Val Asn 20 25 (16) Information for Seq. I.D. No: 16 (i) Characterisation of sequence: (A) Length: 26 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 16 Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Val Asp Gin Tyr Ser As 1 5 10 15 Gin Asn Asn Phe Val His Asp Cys Val Asn 20 25 (17) Information for Seq. I.D. No: 17 (i) Characterisation of sequence: (A) Length: 26 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 17 Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Val Asp Arg Tyr Ser As 1 5 10 15 Gin Asn Asn Phe Val His Asp Cys Val Asn 20 25 (18) Information for Seq. I.D. No: IS (i) Characterisation of sequence: (A) Length: 26 Amino acids (B) Type:. Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 18 Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Met Asp Glu Tyr Ser Asn 1 5 10 15 Gin Asn Asn Phe Val His Asp Cys Val Asn 20 25 (19) Information for Seq. I.D. No: 19 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 19 Tyr Tyr Gin Arg Gly Ala Ser Val He Leu Phe Ser Ser Pro Pro Val 1 5 10 15 He Leu Leu He Ser Phe Leu He Phe Leu He Val Gly 20 25 (20) Information for Seq. I.D. No: 20 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 20 Tyr Tyr Gin Arg Gly Ser Ser Met Val Leu Phe Ser Ser Pro Pro Val 1 5 10 15 He Leu Leu He Ser Phe Leu He Phe Leu He Val Gly 20 25 (21) Information for Seq. I.D. No: 21 (i) Characterisation o: sequence: (A) Length: 17 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 21 Gly Ala Ser Val He Leu Phe Ser Ser Pro Pro Val He Leu Leu H 1 5 10 15 Ser (22) Information for Seq. I.D. No: 22 (i) Characterisation of sequence: (A) Length: 17 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 22 Gly Ser Ser Met Val Leu Phe Ser Ser Pro Pro Val He Leu Leu H 1 5- 10 15 Ser (23) Information for Seq. I.D. No: 23 (i) Characterisation of sequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of εequence: Seq. I.D. No: 23 Pro Gly Gly Gly Trp Aεn Thr Gly Gly Ser Arg Tyr Pro Gly Gin Gl 1 5 10 15 Ser Pro Gly Gly Asn Arg Tyr Pro Pro n Gly Gly Gly Gly Trp 20 25 30 - - (24) Information for Seq. I.D. No: 24 (i) Characterisation of sequence: (A) Length: 16 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of εequence: Seq. I.D. No: 24 Gly Gly Gly Trp Gly Gin Pro His Gly Gly Gly Trp Gly Gin Pro His 1 5 10 15 (25) Information for Seq. I.D. No: 25 (i) Characterisation of sequence: (A) Length: 28 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 25 Gly Gly Gly Trp Gly Gin Gly Gly Thr His Gly Gin Trp Aεn Lys Pro 1 5 10 15 Ser Lys Pro Lys Thr Asn Met Lys His Val Ala Gly 20 25 (26) Information for Seq. I.D. No: 26 (i) Characterisation of sequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 26 Pro Gly Gly Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gin Gly 1 5 10 15 Ser Pro Gly Gly Asn Arg Tyr Pro Pro Gin Gly Gly Gly Gly Trp 20 25 30 (27) Information for Seq. I.D. No: 27 (i) Characterisation of sequence: (A) Length: 16 Amir.-, acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 27 Gly Gly Gly Trp Gly Gin Pro His Gly Gly Gly Trp Gly Gin Pro Hi 1 5 10 15 (28) Information for Seq. I.D. No: 28 (i) Characterisation of sequence: (A) Length: 28 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 28 Gly Gly Gly Trp Gly Gin Gly Gly Ser His Ser Gin Trp Asn Lys Pr 1 5 10 15 Ser Lys Pro Lys Thr Asn Met Lys His Val Ala Gly 20 25 (29) Information for Seq. I.D. No: 29 (i) Characterisation of sequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) - Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 29 Pro Gly Gly Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gin Gl 1 5 10 15 Ser Pro Gly Gly Asn Arg Tyr Pro Pro Gin Gly Gly Gly Gly Trp 20 25 ' 30 (30) Information for Seq. I.D. No: 30 (i) Characterisation of sequence: (A) Length: 16 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 30 Gly Gly Gly Trp Gly Gin Pro His Gly Gly Gly Trp Gly Gin Pro His 1 5 10 15 • (31) Information for Seq. I.D. No: 31 (i) Characteriεation of εequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 31 Gly Gly Gly Trp Gly Gin Gly Gly Gly Thr His Ser Gin Trp Asn Lys 1 5 10 15 Pro Ser Lys Pro Lys Thr Aεn Met Lyε His Met Ala Gly 20 25 (32) Information for Seq. I.D. No: 32 (i) Characterisation of sequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii)- Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 32 Asn Phe Val His Asp Cys Val Aεn He Thr Val Lys Glu His Thr Val 1 5 10 15 Thr Thr Thr Thr Lys Gly Glu Aεn Phe Thr Glu Thr Aεp He Lys 20 25 " 30 (33) Information for Seq. I.D. No: 33 (i) Characterisation of sequence: (A) Length: 20 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 33 Met Cys He Thr Gin Tyr Gin Arg Glu Ser Gin Ala Tyr Tyr Gin A 1 5 10 15 Gly Ala Ser Val 20 (34) Information for Seq. I.D. No: 34 (i) Characterisation of sequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 34 Asn Phe Val His Asp Cys Val Asn He Thr Val Lys Gin His Thr V 1 5 10 15 Thr Thr Thr Thr Lys Gly Glu Asn Phe Thr Glu Thr Asp He Lys 20 25 30 (35) Information for Seq. I.D. No: 35 (i) Characterisation of sequence: (A) Length: 20 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 35 Met Cys He Thr Gin Tyr Gin Arg Glu Ser Gin Ala Tyr Tyr Gin A 1 5 10 15 Gly Ala Ser Val 20 (36) Information for Seq. I.D. No: 36 (i) Characterisation of sequence: (A) Length: 31 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 36 Aεn Phe Val His Asp Cys Val Aεn He Thr He Lys Gin His Thr Val 1 5 10 15 Thr Thr Thr Thr Lys Gly Glu Asn Phe Thr Glu Thr Asp Val Lys 20 25 30 (37) Information for Seq. I.D. No: 37 (i) Characterisation of sequence: (A) Length: 20 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 37 Met Cys He Thr Gin Tyr Glu Arg Glu Ser Gin Ala Tyr Tyr Gin Arg 1 5 10 15 Gly Ser Ser Met 20 (38) Information for Seq. I.D. No: 38 (i) Characterisation of sequence: (A) Length: 5 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 38 Gly Gly Gly Gly Gly 1 5 (39) Information for Seq. I.D. No: 39 (i) Characterisation of sequence: (A) Length: 6 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 39 Gly Pro Gly Pro Gly Pro 1 5 (40) Information for Seq. I.D. No: 40 (i) Characterisation of sequence: (A) Lenqth: 7 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 40 Gly Ser Ala Gly Ser Gly Ala 1 5 (41) Information for Seq. I.D. No: 41 (i) Characterisation of sequence: (A) Length: 26 Amino acids (B) Type: Amino acid (D) Topology: Linear . (ii) Type of molecule: Peptide (xi) Deεcription of εequence: Seq. I.D. No: 41 Ala Met Ser Arg Pro Leu He His Phe Gly Ser Asp Tyr Glu Asp Ar 1 5 10 15 Tyr Tyr Arg Glu Asn Met His Arg Gly Cys 20 25 (42) Information for Seq. I.D. No: 42 (i) Characterisation of sequence: (A) Length: 21 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of εequence: Seq. I.D. No: 42 Ser Ala Met Ser Arg Pro Leu He His Phe Gly Asn Asp Tyr Glu Asp 1 5 10 15 Arg Tyr Tyr Gly Cys 20 (43) Information for Seq. I.D. No: 43 (i) Characteriεation of sequence: (A) Length: 21 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 43 Ser Ala Met Ser Arg Pro Leu He His Phe Gly Ser Asp Tyr Glu Asp 1 5 10 15 Arg Tyr Tyr Gly Cyε 20 (44) Information for Seq. I.D. No: 44 (i) Characterisation of sequence: . (A) Length: 27 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 44 Asn Met Tyr Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Val Asp Arg 1 5 10 15 Tyr Ser Asn Gin Asn Asn Phe Val His Gly Cyε 20 25 (45) Information for Seq. I.D. No: 45 (i) Characterisation of sequence: (A) Length: 27 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Deεcription of sequence: Seq. I.D. No: 45 Asn Met His Arg Tyr Pro Asn Gin Val Tyr Tyr Arg Pro Val Asp Gi 1 5 10 15 Tyr Ser Asn Gin Asn Asn Phe Val His Gly Cys 20 25 (46) Information for Seq. I.D. No: 46 (i) Characterisation of sequence: (A) Length: 26 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of εequence: Seq. I.D. No: 46 Gly Gin Pro His Gly Gly Gly Trp Gly Gin Pro His Gly Gly Gly Tr 1 5 10 15 Gly Gin Pro His Gly Gly Gly Trp Gly Cys 20 25 (47) Information for Seq. I.D. No: 47 (i) Characterisation of sequence: • (A) Length: 24 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 47 Gly Gin Gly Gly Ser His Ser Gin Trp Asn Lys Pro Ser Lys Pro Ly 1 5 10 15 Thr Asn Met Lys His Val Gly Cys 20 (48) Information for Seq. I.D. No: 48 (i) Characterisation of sequence: (A) Length: 15 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 48 Cys He Thr Gin Tyr Gin Arg Glu Ser Gin Ala Tyr Tyr Gin Arg 1 5 10 15 (49) Information for Seq. I.D. No: 49 (i) Characterisation of sequence: (A) Length: 28 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 49 Gly Gly Trp Asn Thr Gly Gly Ser Arg Tyr Pro Gly Gin Gly Ser Pro 1 - 5 10 15 Gly Gly Asn Arg Tyr Pro Pro Gin Gly Gly Gly Cys 20 25 Peptide Villa: (Seq. I.D. No: 50) (50) Information for Seq. I.D. No: 50 (i) Characterisation of sequence: (A) Length: 23 Amino acids • (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 50 Val Asn He Thr Val Lys Gin Hiε Thr Val Thr Thr Thr Thr Lys Gly 1 5 10 15 Glu Asn Phe Thr Glu Gly Cys 20 (51) Information for Seq. I.D. No: 51 (i) Characterisation of sequence: (A) Length: 29 Amino acids (B) Type: Amino acid (D) Topology: Linear (ii) Type of molecule: Peptide (xi) Description of sequence: Seq. I.D. No: 51 Lys His Met Ala Gly Ala Ala Ala Ala Gly Ala Val Val Gly Gly Le 1 5 10 15 Gly Gly Tyr Met Leu Gly Ser Ala Met Ser Arg Gly Cys. 20 25

Claims: Claimε 1. A εynthetic polypeptide having at leaεt one antigenic site of a prion protein. 2. A synthetic polypeptide as claimed in claim 1 in which the prion protein is of a form which only exists in nervous tiεsue of a mammal εuffering from spongiform encephalopathy. 3. A synthetic polypeptide as claimed in claim 1 comprising εequence according to general formula (I) : X-(R.)Lys-His-R 2 ) -Ala-Gly-Ala-Ala-Ala-R 3 -Gly-Ala-Val- Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala-Met- Ser-(Arg-Pro-R 4 -R 5 ) -Y (I) wherein R 1 is an amino acid residue selected from Met, Leu and Phe; R j , is either Met or Val; R 3 is Ala or is abεent; R 4 and R 5 are independently an amino acid reεidue εelected from Leu, He and Met; one or more reεidueε within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more additional amino acid residues. 4. A synthetic polypeptide as claimed in claim 3 comprising a sequence selected from Seq. I.D. No: 1 X-(Met-Lys-His-Val)-Ala-Gly-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser-(Arg-Pro-Leu-He) -Y; and Seq . I . D . No : 2 X- (Met-Lys-His-Met) -Ala-Gly-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser- (Arg-Pro-He-Ile ) -Y . 5. A synthetic polypeptide as claimed in claim 3 consisting of the sequence Seq. I.D. No: 51 Lys-His-Met-Ala-Gly-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-Gly-Leu-Gly-Gly-Tyr-Met-Leu-Gly-Ser-Ala- Met-Ser-Arg-Gly-Cyε. 6. A εignificant sub-fragment of a sequence claimed in claim 3 preferably selected from i) X-(Hiε-R 2 -Ala-Gly) -Ala-Ala-Ala-R 3 -Gly-Ala-Val- Val-(Gly-Gly-Leu-Gly) -Y and; ii) X-(Gly-Gly-Leu-Gly) -Gly-Tyr-Met-Leu-Gly-Ser- Ala-Met-Ser-(Arg-Pro-R -R 5 )-Y wherein R 2 , R 3 , R 4 , R 5 , X and Y are as defined for formula I and one or more residues in brackets may be absent or present aε in formula I. 7. A sub-fragment as claimed in claim 6 selected from Seq. I.D. No: 3 i) X-(His-Val-Ala-Gly)-Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly-(Gly-Leu-Gly-Gly)-Y; Seq. I.D. " No: 4 ii) (Gly-Gly-Leu-Gly) -Gly-Tyr-Met-Leu-Gly-Ser- Ala-Met-Ser-(Arq-Pro-Leu-He) -Y Seq. I.D. No: 5 i) X-(His-Met-Ala-Gly) -Ala-Ala-Ala-Ala-Gly-Ala- Val-Val-Gly- (Gly-Leu-Gly-Gly) - ; and Seq. I.D. No: 6 ii) X-(Gly-Gly-Leu-Gly) -Gly-Tyr-Met-Leu-Gly-Ser- Ala-Met-Ser-(Arg-Pro-He-Ile)-Y. 8. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to general formula II: X-(Ser-Ala-Met-Ser) -Arg-Pro-R 4 -R 5 -His-Phe-Gly-R 6 - Aεp-R 7 -Glu-Aεp-Arg-Tyr-Tyr-Arg-Glu-Aεn-Met-R 8 -Arg- (Tyr-Pro-Aεn-Gln) -Y (II) wherein R 4 and R 5 are the same as in formula I; R 6 is either Asn or Ser; R 7 is either Tyr or Trp; R 8 is an amino acid residue selected from His, Tyr and Asn; one or more reεidueε within bracketε maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more additional amino acid residues. 9. A synthetic polypeptide as claimed in claim 8 comprising a sequence selected from Seq. I.D. No: 7 X-(Ser-Ala-Met-Ser) -Arg-Pro-Leu-He-His-Phe-Gly-Ser- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-His-Arg- (Tyr-Pro-Asn-Gln)-Y; Seq. I.D. No: 8 X-(Ser-Ala-Met-Ser) -Arg-Pro-Leu-He-His-Phe-Gly-Asn- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-Tyr-Arg- (Tyr-Pro-Asn-Gln ) -Y ; and Seq. I . D . No : 9 X- (Ser-Ala-Met-Ser) -Arg-Pro-Ile-He-His-Phe-Gly-Ser- Asp-Tyr-Glu-Aεp-Arg-Tyr-Tyr-Arg-Glu-Asn-Met-His-Arg- (Tyr-Pro-Asn-Gln) -Y . 10. A synthetic polypeptide as claimed in claim 8 selected from Sp . I.D. No: 42 Ser-Ala-Iv --Ser-Arg-Pro-Leu-He-His-Phe-Gly- Asn-Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-Gly-Cys; and Seq. I.D. No: 43 Ser-Ala-Met-Ser-Arg-Pro-Leu-Ile-His-Phe-Gly- Ser-Aεp-Tyr-Glu-Aεp-Arg-Tyr-Tyr-Gly-Cys. 11. A εignificant sub-fragment of a sequence as claimed in claim 8 preferably comprising the sequence:- X-(Ser-Ala-Met-Ser)-Arg-Pro-R 4 -R--His-Phe-Gly-R 6 - Aεp-R 7 -Glu-Aεp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met)-Y wherein R A to R-, X and Y are as defined in formula II and one or more residues in brackets may be present or absent. 12. A sub-fragment as claimed in claim 11 selected from Seq. I.D. No: 10 X-(Ser-Ala-Met-Ser)-Arg-Pro-Leu-He-His-Phe-Gly-Ser- Asp-Tyr-Glu-Aεp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met)-Y; Seq. I.D. No: 11 X-(Ser-Ala-Met-Ser)-Arg-Pro-Leu-He-His-Phe-Gly-Asn- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr-(Arg-Glu-Asn-Met)-Y; and. Seq. I.D. No: 12 X- (Ser-Ala-Met-Ser) -Arg-Pro-Ile-He-His-Phe-Gly-Ser- Asp-Tyr-Glu-Asp-Arg-Tyr-Tyr- (Arg-Glu-Asn-Met) -Y . 13. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to general formula III: X-(Asn-Met-R 8 -Arg) -Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-R 9 -Asp-R 10 -Tyr-R -Aεn-Gln-Aεn-Asn-Phe-Val-His- (Asp-Cyε-Val-Asn) -Y (III) wherein R g is an amino acid residue selected from His, Tyr and Asn; R ς , is Val or Met; R 10 is an amino acid residue selected from Gin, Glu and Arg; R.,. is Ser or Asn; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence and X and Y may each independently be absent or independently be one or more additional amino acid residues. 14. A synthetic polypeptide as claimed in claim 13 comprising a sequence selected from Seq. I.D. No: 13 X-(Asn-Met-His-Arg)-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-Val-Asp-Gln-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- ' (Asp-Cyε-Val-Aεn)-Y; Seq. I.D. No: 14 X-(Asn-Met-Tyr-Arg) -Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-Val-Asp-Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y; and Seq. I . D. No : " 5 X- (Aεn-Met~ s-Arg) -Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg- Pro-Met-Asp— Jlu-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn) -Y . 15. A synthetic polypeptide as claimed in claim 14 selected from Seq. I.D. No: 44 Asn-Met-Tyr-Arg-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg-Pro-Val- Asp-Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His-Gly-Cys; and Seq. I. ). No: 45 Asn-Met-His-Arg-Tyr-Pro-Asn-Gln-Val-Tyr-Tyr-Arg-Pro-Val- Asp-Gln-Tyr-Ser-Asn^-Gln-Asn-Asn-Phe-Val-His-Gly-Cys. 16. A significant sub-frafment of a sequence as claimed in claim 13 preferably comprising the sequence: X-(Arg-Tyr-Pro-Asn) -Gln-Val-Tyr-Tyr-Arg-Pro-R 9 -Asp- R- Kj -Tyr-R^-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y. wherein R 9 , R 10 , R , X and Y are as defined in formula (III) . 17. A sub-fragment as claimed in claim 16 selected from Seq. I.D. No: 16 X-(Arg-Tyr-Pro-Asn) -Gln-Val-Tyr-Tyr-Arg-Pro-Val-Asp- Gln-Tyr-Ser-Asn-Gln-Asn-Aεn-Phe-Val-His- (Asp-Cys-Val-Asn)-Y; Seq. I.D. No: 17 X-(Arg-Tyr-Pro-Asn) -Gln-Val-Tyr-Tyr-Arg-Pro-Val-Asp- Arg-Tyr-Ser-Asn-Gln-Asn-Asn-Phe-Val-His- (Asp-Cys-Val-Aεn) -Y; and Seq. I . D. No : 18 X- (Arg) -Tyr-Pro-Asn). -Gln-Val-Tyr-Tyr-Arg-Pro-Met-Asp- Glu-Tyr-Ser-Asn-Gln-Aεn-Asn-Phe-Val-His- (Asp-Cys-Val-Asn) -Y. 18. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to general formula IV: X-(Tyr-Tyr-R 12 -R 13 -Arg)-R u -R l5 -Ser-R 16 -R t7 -R 18 -Leu-Phe-Ser- Ser-Pro-Pro-Val-Ile-Leu-Leu-Ile-Ser-Phe-Leu-He-Phe- Leu-R 19 -Val-Gly-Y (IV) wherein R 12 is Asp or Gin; R 13 is Gly or absent; R 14 is Gly or Arg; R 15 is Ala or Ser; R 16 iε Ser or absent; R 17 is an amino acid reεidue εelected from Ala, Thr, Met and Val; R 18 iε Val or lie; R 19 iε He or Met; one or more reεidueε within brackets may be present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence and X and Y may each independently be absent or independently be one or more additional amino acid residues. 19. A synthetic polypeptide as claimed in claim 18 comprising a sequence selected from Seq. I.D. No: 19 X-(Tyr-Tyr-Gln-Arg)-Gly-Ala-Ser-Val-Ile-Leu-Phe-Ser- Ser-Pro-Pro-Val-Ile-Leu-Leu-Ile-Ser-Phe-Leu-He-Phe- Leu-He-Val-Gly-Y; and Seq. I.D. No: 20 X-(Tyr-Tyr-Gln-Arg)-Gly-Ser-Ser-Met-Val-Leu-Phe-Ser-Ser- Pro-Pro-Val-Ile-Leu-Leu-Ile-Ser-Phe-Leu-Ile- Phe-Leu-He-Val-Gly-Y. 20. A significant sub-fragment of a sequence as claimed in claim 18 preferably comprising the sequence: X-(-R 14 -R 15 -Ser-R 16 -R 17 ) -R 18 -Leu-Phe-Ser-Ser-Prσ-Pro-Val- Ile- (Leu-Leu-Ile-Ser) -Y Wherein R u to R 18 , X and Y are as defined in formula IV and one or more residues within brackets may be present or absent as in formula IV. 21. A sub-fragment as claimed in claim 20 selected from Seq. I.D. No: 21 X-(Gly-Ala-Ser-Val)Ile-Leu-Phe-Ser-Ser-Pro-Pro-Val- Ile-(Leu-Leu-Ile-Ser) -Y; and Seq. I.D. No: 22 X-(Gly-Ser-Ser-Met) -Val-Leu-Phe-Ser-Ser-Pro-Pro-Val- He-(Leu-Leu-Ile-Ser) -Y. 22. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to general formulae Va, Vb and Vc: X-(Pro-Gly-Gly-R 20 ) -Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Aεn-Arg-Tyr-Pro-Pro- Gln-Gly-(Gly-R 21 -R 22 -Trp)-Y (Va) ; X-(Gly-Gly-R 2 .-R 22 -Trp)-Gly-Gln-Pro-His-Gly-Gly-Gly- R 23 -Trp(Gly-Gln-Pro-Hiε)-Y (Vb) ; and X-(Gly-Gly-Gly-Trp)-Gly-Gln-Gly-Gly-R 24 -R 25 -His-R 20 - Gln-Trp-Asn-Lys-Pro-R 27 -Lys-Pro-Lys-Thr-R 28 -R 29 -Lys (-His-R 30 -Ala-Gly)-Y (Vc) Wherein R 20 , R 21 , R 23 and R-, 4 are each independently either Gly or absent; R 22 either Gly or Thr; R 25 is either Thr or Ser; R 26 iε an amino acid reεidue selected from Gly, Ser and Asn; R 27 and R 28 are each independently either Asn or Ser; R 29 iε an amino acid reεidue εelected from Met, Leu and Phe; R 30 iε either Val or Met; one or more reεidueε within bracketε maybe present or absent with the proviso that if they are preεent they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more additional amino acid residues. 23. A synthetic polypeptide as claimed in claim 22 comprising a εequence εelected from Seq. I.D. No: 23 X-(Pro-Gly-Gly-Gly) -Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Aεn-Arg-Tyr-Pro-Pro- Gln-Gly-(Gly-Gly-Gly-Trp) -Y; Seq. I.D. No: 24 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Pro-His-Gly-Gly-Gly-Trp- (Gly-Gln-Pro-Hiε) -Y; Seq. I.D. No: 25 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Gly-Gly-Thr-His-Gly-Gln- Trp-Asn-Lys-Pro-Ser-Lys-Pro-Lys-Thr-Asn-Met-Lys (-His-Val-Ala-Gly) -Y; Seq. I.D. No: 26 X-(Pro-Gly-Gly-Gly)-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro- Pro-Gln-Gly-(Gly-Gly-Gly-Trp)-Y; Seq. I.D. No: 27 X-(Gly-Gly-Gly-Trp)-Gly-Gln-Pro-His-Gly-Gly- Gly-Trp-(Gly-Gln-Pro-His) -Y; Seq. I.D. No: 28 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Gly-Gly-Ser-His- Ser-Gln-Trp-Asn-Lys-Pro-Ser-Lys-Pro-Lys-Thr- Asn-Met-Lys (-His-Val-Ala-Gly) -ϊ , Seq. I.D. No: 29 X-Pro-Gly-Gly-Gly-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr-Pro- Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro-Pro- Gln-Gly-(Gly-Gly-Gly-Trp) -Y; Seq. I.D. No: 30 X-(Gly-Gly-Gly-Trp) -Gly-Gln-Pro-His-Gly-Gly-Gly- Trp-(Gly-Gln-Pro-His) -Y; and Seq. I.D. No: 31 X-(Gly-Gly-Gly-Trp)-Gly-Gln-Gly-Gly-Gly-Thr-His-Ser- Gln-Trp-Asn-Lys-Pro-Ser-Lys-Pro-Lys-Thr-Asn-Met-Lys (-His-Met-Ala-Gly)-Y. 24. A synthetic polypeptide as claimed in claim 21 selected from Seq. I.D. No: 49 Gly-Gly-Trp-Asn-Thr-Gly-Gly-Ser-Arg-Tyr- Pro-Gly-Gln-Gly-Ser-Pro-Gly-Gly-Asn-Arg-Tyr-Pro- Pro-Gln-Gly-Gly-Gly-Cys Seq. I.D. No: 46 Gly-Gln-Pro-His-Gly-Gly-Gly-Trp-Gly-Gln-Pro-Hiε-Gly-Gly- Gly-Trp-Gly-Gln-Pro-His-Gly-Gly-Gly-Trp-Gly-Cys; and Seq. I.D. No: 47 Gly-Gln-Gly-Gly-Ser-His-Ser-Gln-Trp-Asn-Lys-Pro- Ser-Lys-Pro-Lys-Thr-Asn-Met-Lys-His-Val-Gly-Cys. 25. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to formula VI: X-(R 31 -R 32 -Trp-R 33 )-Trp-Leu-Gly-R 34 -R 35 -R 3ό -Trp-R 37 (Trp-Leu-Gly-R 38 )-Y (VI) Wherein R 31 and R 35 are each independently either Ala or Thr; R 32 and R 36 are each independently an amino acid residue selected from Ser, Pro and Thr; R 33 and R 37 are each independently either Trp or Arg; R 34 and R 38 are each independently an amino acid residue selected from Ala, Ser, Pro and Thr; one or more residues within brackets maybe preεent or abεent with the proviεo that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more, additional amino acid reεidues. 26. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to formula VII: X-(R 39 -R 40 -Met-R 41 )-Val-Ala-Gly-R 42 -R 43 -R 44 -Met-R 45 - (Val-Ala-Gly-R 46 )-Y (VII) Wherein R 39 and R 43 are each independently either Ser or Asn; R 40 and R 44 are each independently an amino acid residue selected from Pro, Leu and His, R 41 and R 45 are each independently Val or Glu; R 42 and R 46 are each independently selected from Val, Ala, Asp and Gly; one or more residues within brackets maybe present or absent with the proviso that if they are present they are attached to the rest of the peptide in sequence; and X and Y may each independently be absent or independently be one or more, additional amino acid residues. 27. A synthetic polypeptide as claimed in claim 1 comprising a sequence according to formula Villa or Vlllb : X- (Asn-Phe-Val-His ) -Asp-Cys-Val-Asn-He-Thr-R 47 -Lys- R 48 -Hiε-Thr-Val-R 49 -Thr-Thr-Thr-Lyε-Gly-Glu-Asn- Phe-Thr-Glu- (Thr-Asp-R 50 -Lys ) -Y (Villa ) X-(Met-Cys-R 51 -Thr) -Gln-Tyr-R 52 -R 53 -Glu-Ser-Gln-Ala- Tyr-Tyr-R 54 -R 55 -Arg-(R 56 -R 57 -Ser-R 58 -R 59 ) -Y (Vlllb) Wherein R 47 is either He or Val; R 48 and R 52 are each independently either Gin or Glu; R 49 is either Val or Thr; R 50 is either Val or lie; R 51 is an amino acid residue selected from He, Thr and Val; R 52 is Gin or Glu; R 53 is either Arg or Lys; R 54 is either Asp or Gin; R 55 is Gly or is absent; R 56 is either Gly or Arg; R 57 is either Ala or Ser; R 58 is Ser or absent; R 59 is an amino acid residue selected from Ala, Thr, Met and Val; one or more residues within brackets maybe present or abεent with the proviεo that if they are preεent they are attached to the reεt of the peptide in εequence; and X and Y may each independently be abεent or independently be one or more, additional amino acid reεidues. 28. A synthetic polypeptide as claimed in claim 27 comprising a sequence selected from: Seq I.D. No: 32 X-(Asn-Phe-Val-His)-Asp-Cys-Val-Asn-He-Thr-Val-Lys- Glu-His-Thr-Val-Thr-Thr-Thr-Thr-Lys-Gly-Glu-Asn- Phe-Thr-Glu-(Thr-Asp-Ile-Lys) -Y; Ξ . Seq. I.D. No: 33 X-(Met-Cys-Ile-Thr)-Gln-Tyr-Gln-Arg-Glu-Ser-Gln-Ala- Tyr-Tyr-Gln-Arg-(Gly-Ala-Ser-Val) -Y; Seq. I.D. No: 34 X-(Asn-Phe-Val-His) -Asp-Cys-Val-Asn-Ile-Thr-Val-Lys- Gln-His-Thr-Val-Thr-Thr-Thr-Thr-Lys-Gly-Glu-Asn- Phe-Thr-Glu-(Thr-Asp-Ile-Lys) -Y; Seq. I.D. No: 35 X-(Met-Cys-Ile-Thr) -Gln-Tyr-Gln-Arg-Glu-Ser-Gln-Ala- Tyr-Tyr-Gln-Arg-(Gly-Ala-Ser-Val) -Y; Seq. I.D. No: 36 X-(Asn-Phe-Val-His)-Asp-Cys-Val-Asn-Ile-Thr-He-Lys- Gln-His-Thr-Val-Thr-Thr-Thr-Thr-Lys-Gly-Glu-Asn- Phe-Thr-Glu-(Thr-Asp-Val-Lys)-Y; and Seq. I.D. No: 37 X-(Met-Cys-Ile-Thr) -Gln-Tyr-Glu-Arg-Glu-Ser-Gln-Ala- Tyr-Tyr-Gln-Arg-(Gly-Ser-Ser-Met)-Y. 29. A synthetic polypeptide as claimed in claim 27 selected from Seq. I.D. No: 50 Val-Asn-Ile-Thr-Val-Lys-Gln-His-Thr-Val-Thr-Thr-Thr-Thr- Lys-Gly-Glu-Asn-Phe-Thr-Glu-Gly-Cys; and Seq. I.D. No: 48 Cys-Ile-Thr-Gln-Tyr-Gln-Arg-Glu-Ser-Gln-Ala-Tyr-Tyr-Gln-Arg. 30. A synthetic polypeptide of general formula (IX) : [ L a- F l m - ^b- G ] n- L c ( I X ) wherein F and G may each independently be a polypeptide or sub-fragment according to any one of Formulae I to Vlllb, L is a linking sequence, a, b and c are each independently 0 or 1 and m and n are each positive numbers. 31. A synthetic polypeptide which comprises an antigenically significant subfragment and/or antigenically εignificant variant of the above-identified polypeptide sequences as claimed in 1 to 29. 32. A synthetic polypeptide as claimed in any one of the preceding claims additionally comprising a T-cell epitope. 33. A synthetic polypeptide as claimed in any one of the preceding claims including a retro-inverso amino acid. 34. A synthetic polypeptide as claimed in any one of preceding claims linked to a carrier. 35. A DNA molecule coding for at least one synthetic polypeptide as claimed in any one of claims 1 to 32. 36. A vaccine comprising at least one polypeptide as claimed in any one of claimε 2 to 33 effective to promote prophylaxiε against encephalopathies. 37. A kit for detecting prion proteins or antibodies against prion proteins which comprises at least one synthetic polypeptide as claimed in any one of claims 1 to 33. 38. A pharmaceutical composition containing as active ingredient, at least one polypeptide or polypeptide- carrier conjugate as claimed in any one of claims 2 to 34 in association with one or more pharmaceutically acceptable adjuvants, carriers and/or excipients. 39. Use of a synthetic polypeptide as claimed in any one of claims 2 to 34 for the preparation of a medicament for the therapeutic.or prophylactic treatment of mammalian encephalopathies and/or blocking the cellular binding or aggregation of the prion proteins. 40. A method of therapy or prophylaxis of mammalian encephalopathies and/or of stimulating the mammalian immune system and/or of blocking the cellular binding or aggregation of the prion proteins, which comprises administering an amount of a polypeptide as claimed in any one of claims 2 to 34, either in isolation or in combination with other agents for the treatment of encephalopathies. 41. A method of detecting prion protein or antibodies against prion protein or antigen binding fragments thereof, which comprises incubating a sample with at least one polypeptide as claimed in any one of claims 1 to 34. 42. A method of discriminating between PrP c and PrP sc in which a sample is contacted with a substance selected from peptide sequences as claimed in any one of claims 2 to 24 preferably those relating to regions A, B and C, and significant sub-fragments thereof, antibodies raised against said sequences and sub-fragments -and the presence or absence of PrP sc is determined. 43. An antibody or antigen binding fragment thereof which specifically binds to a synthetic polypeptide as claimed in any one of claims 1 to 33. 44. A kit for detecting prion proteins or antibodies against prion proteins which contains an antibody or antigen binding fragment thereof, as claimed in claim 43. 45. A pharmaceutical composition comprising, as active ingredient, an antibody or antigen binding fragment as claimed in claim 43 in association with one or more pharmaceutically acceptable, carriers and/or excipients. 46. A method of therapy or prophylaxis of mammalian encephalopathies which comprises administering an antibody or antigen binding fragment as claimed in claim 43. 47. A method detecting prion proteins or antibodies against prion proteins which comprises incubating a sample with an antibody or antigen binding fragment as claimed in claim 43. 48. An anti-idiotypic antibody raised against an antibody or antigen binding fragment as claimed in claim 43. 49. A process for the manufacture of a synthetic polypeptide having at least one antigenic site of a prion protein, the process comprising the steps of coupling the residues using chemical, biological or recombinant techniques ;n per se and iεolating the polypeptide as defined ny one of claims 1 to 33. 50. A process for the manufacture of an antibody which specifically binds to a synthetic polypeptide having at least one antigenic site of a prion protein, the process comprising immunising a non-human mammal with said polypeptide and isolating the antibody as defined in claim 43.

Inventors: FISHLEIGH ROBERT VINCENT, MEE ROGER PAUL, ROBSON BARRY, FISHLEIGH, ROBERT, VINCENT, MEE, ROGER, PAUL, ROBSON, BARRY
Applicants: PROTEUS MOLECULAR DESIGN, PROTEUS MOLECULAR DESIGN LIMITED
Application year: 1992
Main classification: C07K7
IPC codes: A61K38, A61K39, C07K7, C07K14, C07K16, G01N33