Manipulation of antipeptide immune response by varying the coupling of the peptide with the carrier protein

Development of a gold nanoparticle-based novel diagnostic prototype for in vivo detection of Indian red scorpion (Mesobuthus tamulus) venom

Indian red scorpion Mesobuthus tamulus is responsible for substantial mortality in India and Sri Lanka; however, no specific diagnostic method is available to detect the venom of this scorpion in envenomed plasma or body fluid. Therefore, we have proposed a novel, simple, and rapid method for detecting M. tamulus venom (MTV) in the plasma of envenomed animals using polyclonal antibodies (PAb) raised against three modified custom peptides representing the antigenic epitopes of K+ (Tamapin) and Na+ (α-neurotoxin) channel toxins, the two major MTV toxins identified by proteomic analysis. The optimum PAb formulation containing PAb 1, 2, and 3 in proportion (1:1:1, w/w/w) acted synergistically, demonstrating significantly higher immunological recognition of MTV than anti-scorpion antivenom (developed against native toxins) and individual antibodies against peptide immunogens. The PAb formulation could detect MTV optimally in envenomed rat plasma (intravenous and subcutaneous routes) at 30-60 min post-injection. The acetonitrile precipitation method developed in this study to augment the MTV detection sensitivity enriched the low molecular mass peptide toxins in envenomed rat plasma, which was ascertained by mass spectrometry analysis. The gold nanoparticles conjugated PAb formulation, characterised by biophysical techniques such as Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM), demonstrated their interaction with low molecular mass MTV peptide toxins in envenomed rat plasma. This interaction results in the accumulation of the gold nanoparticles, thus leading to signal change in absorbance spectra that can be discerned within 10 min. From a standard curve of MTV spiked plasma, the quantity of MTV in envenomed rat plasma could be determined by gold nanoparticle-PAb formulation conjugate.

Peptide-Carrier Conjugation

To produce antibodies against synthetic peptides, it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined.

Amino Acid Variations of The Immuno-Dominant Domain of Respiratory Syncytial Virus Attachment Glycoprotein (G) Affect the Antibody Responses In BALB/c Mice

Respiratory syncytial virus (RSV) is the leading cause of respiratory illness in ruminants and infants. The G glycoprotein of RSV serves as the viral attachment ligand. Despite currently available vaccines, RSV immunity is insufficient, and re-infections occur. Vaccine studies employing the G-protein's 174-187 amino acids, representing the immunodominant domain, have protected mice and calves against infections. To investigate the causes of vaccination failure, we designed four synthetic peptides for the ruminant RSV isolates (391-2, Maryland-BRSV, European-BRSV, and ORSV) using the immune-dominant sequence and vaccinated mice groups with them. The produced antibodies targeting each peptide were evaluated using ELISA and flow cytometry to determine their reactivity against the linear antigen and the native form of the G protein, respectively. Antibodies responded to homologous and heterologous peptides as determined by ELISA. Using flow cytometry-analysis targeting the natively folded protein, most generated antibodies reacted only with their homologous strain. However, antibodies raised to 391-2 peptide reacted with homologous and heterologous Maryland-BRSV viral epitopes. Accordingly, inadequate immunity and recurring RSV infections might be attributed to variations of antibodies targeting the immunodominant region of the G-protein.

Synthesis and Characterization of Site-Selective Orbitide-BSA Conjugate to Produce Antibodies

Bioactive flax cyclic peptides (orbitides and linusorbs) were site-specifically ligated through methionine with bovine serum albumin (BSA) to produce immunogenic compounds. In this study, modified flaxseed immunosuppressant orbitides (linusorbs or LOs) containing hydroxyl (OH) groups were synthesized for use as haptens. These compounds were extensively characterized by ¹H nuclear magnetic resonance (NMR), ¹³C NMR, high-performance liquid chromatography-tandem mass spectrometry, and Fourier transform infrared spectroscopy. The haptens were conjugated to BSA, and the extent of hapten incorporation was determined by matrix-assisted laser desorption and ionization, liquid chromatography-electrospray ionization-mass spectrometry, and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The BSA hapten complexes were used to elicit polyclonal antibody (pAbs) production in rabbits. A competitive indirect enzyme-linked immunosorbent assay (CI-ELISA) was developed that used orbitide-specific pAbs and horseradish peroxidase (HRP) conjugates. The LO assay detection limit was approximately 0.01 μg/mL (ppm), and thus, ELISA can be used for the detection of LOs in tissue and plant samples. The pAbs can be used to detect and quantify LOs in flax and flaxseed samples, to verify the presence of LOs in flaxseed containing foods, and for the detection of LOs in tissue samples, wastes, and body fluids of animals fed flaxseed.

Peptide-Carrier Conjugation

To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined.

Production and characterization of peptide antibodies

Proteins are effective immunogens for generation of antibodies. However, occasionally the native protein is known but not available for antibody production. In such cases synthetic peptides derived from the native protein are good alternatives for antibody production. These peptide antibodies are powerful tools in experimental biology and are easily produced to any peptide of choice. A widely used approach for production of peptide antibodies is to immunize animals with a synthetic peptide coupled to a carrier protein. Very important is the selection of the synthetic peptide, where factors such as structure, accessibility and amino acid composition are crucial. Since small peptides tend not to be immunogenic, it may be necessary to conjugate them to carrier proteins in order to enhance immune presentation. Several strategies for conjugation of peptide-carriers applied for immunization exist, including solid-phase peptide-carrier conjugation and peptide-carrier conjugation in solution. Upon immunization, adjuvants such as Al(OH)(3) are added together with the immunogenic peptide-carrier conjugate, which usually leads to high-titred antisera. Following immunization and peptide antibody purification, the antibodies are characterized based on their affinity or specificity. An efficient approach for characterization of peptide antibodies is epitope mapping using peptide based assays. This review describes standard solid-phase approaches for generation of peptide antibodies with special emphasis on peptide selection, generation of peptide conjugates for immunization and characterization of the resulting peptide antibodies.

Specific inhibition of AGC protein kinases by antibodies against C-terminal epitopes

The sequences contributing to the catalytic site of protein kinases are not all comprised within the highly conserved catalytic core. Thus, in mammalian cAMP-dependent protein kinase (PKA), the C-terminal sequence participates in substrate binding. Using synthetic peptides mimicking the FxxF motif present at most C-termini of AGC kinases, we have raised highly specific antibodies which are potent and specific inhibitors of the catalytic activity of the cognate protein kinase. Taking into account the structure of PKA, these results point to the potential of the C-terminal region of protein kinases as a target for designing specific protein kinase inhibitors.

Synthesis and immunochemical characterization of protein conjugates of carbohydrate and carbohydrate-mimetic peptides as experimental vaccines

The peptides DRPVPY and MDWNMHAA, which were identified as mimics of the cell-surface polysaccharides of Streptococcus Group A and Shigella flexneri Y, respectively, were used in this study to develop experimental vaccines directed against these two bacteria. Both oligopeptides were synthesized employing the Fmoc solid-phase strategy and linked via the amino end to a bifunctional linker, diethylsquarate. These adducts were then conjugated to the two carrier proteins, bovine serum albumin (BSA) and tetanus toxoid (TT) to yield the peptide conjugate vaccines. The average level of incorporation of DRPVPY and MDWNMHAA on TT was 65% and 75%, respectively, whereas that of both peptide haptens on BSA was 100%. A polysaccharide conjugate against S. flexneri Y, which comprises about 10 tetrasaccharide repeating units, was also prepared based on reductive amination at the reducing end with 1,3-diaminopropane, followed by coupling of the aminated polysaccharide to diethylsquarate, and subsequent coupling of the adduct to TT. An average incorporation of 73% of polysaccharide haptens was achieved. The glycoconjugate and the oligopeptide conjugates were shown to bind effectively to the respective monoclonal antibodies directed against the cell-surface polysaccharides.

Influence of carrier protein conjugation site and terminal modification of a GnRH-I peptide sequence in the development of a highly specific anti-fertility vaccine. Part I

PROBLEM

We previously immunoneutralized gonadotrophin releasing hormone (GnRH), using an analogue of GnRH (des-1 GnRH-I), conjugated to tetanus toxoid via a carbodiimide reaction. The castration effect on the reproductive system was not consistent in all the treated animals. Therefore, we examined the possibility that conjugation to the carrier protein via the N- or C-terminal could have an effect on efficacy.

METHOD OF STUDY

GnRH analogue sequences were synthesized consisting of an additional cysteine at either terminal and specific conjugation was carried out using a bifunctional linker agent.

RESULTS

Conjugation of the monomer through the N-terminal proved to be a highly effective means of causing immunocastration in terms of decreased gonadotrophin and testosterone concentrations and testicular size, whereas conjugation through the C-terminal proved to be ineffective. This was reflected in the ability of the antibodies to bind native GnRH, but not the levels of the anti-GnRH antibodies.

CONCLUSION

Immunoneutralization efficacy was attributed to the importance of preserving the GnRH C-terminal.

Study of different coupling agents in the conjugation of a V3-based synthetic MAP to carrier proteins

The conjugation of synthetic peptides to carrier proteins is a widely used method for immunological studies. Different coupling agents have been described to form the conjugate with carrier proteins. In this paper, we demonstrate that the antibody response toward V3-based synthetic MAPs derived from HIV-1, JY1 isolate, conjugated to two different carrier proteins using either m-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS) or beta-maleimidopropionic acid N-hydroxysuccinimide ester (MPS), or succinic anhydride (SA) show different behaviors. An excellent anti-JY1 response without a strong response to the coupling agent is observed in the case of succinic anhydride spacer. In contrast, MBS produces total abrogation of the antibody response with a high response toward the coupling agent.

Effect of peptide-carrier coupling on peptide-specific immune responses

Synthetic peptides are covalently linked to immunogenic carrier proteins to enhance the anti-peptide immune response. To investigate whether the method of conjugation influences the immune response, we evaluated two distinctly different choices of linker for a peptide-carrier construct. HPG-30, a synthetic peptide derived from the p17 gag protein of human immunodeficiency virus 1, was covalently linked to keyhole limpet hemocyanin by either glutaraldehyde or a maleimide ester. Glutaraldehyde linkage enhanced the anti-peptide antibody and native protein response compared to maleimide. The maleimide-linked conjugate was more effective at inducing a peptide-specific cellular response. Thus, manipulation of the conjugation method can modify the magnitude and character of the immune response to a synthetic peptide vaccine.

Has active immunization against gonadotrophin-releasing hormone any effect on testis innervation in the pig? An immunohistochemical study

The innervation of porcine testes was studied in intact animals and in boars undergoing active immunization against gonadotrophin-releasing hormone (GnRH) by means of immunohistochemistry using antibodies to tyrosine hydroxylase (TH), dopamine beta-hydroxylase (D beta H), vasoactive intestinal polypolypeptide (VIP), neuropeptide Y (NPY), synaptosome-associated protein of 25 kDa (SNAP-25) and protein gene product 9.5 (PGP 9.5). Moreover, the distribution of luteinizing hormone (LH) receptors in clusters of Leydig cells was also investigated. To identify these cells easily, either the NADPH-diaphorase histochemical technique or the Mayer counter-staining procedure was applied. Differences in the distribution pattern and relative density of particular subsets of intratesticular nerve fibres were observed in immunized boars as compared to those found in the intact animals. In the testes of non-treated animals, only single TH-immunoreactive (TH-IR) nerve fibres were observed. However, many D beta H-IR nerve terminals surrounded blood vessels in the tunica albuginea and parenchyma. Very scarce VIP-IR nerves occurred only in the tunica albuginea, mainly in close vicinity to blood vessels. Immunoreactivity to NPY occurred in single nerve fibres. Immunoreactivity to SNAP-25 and PGP 9.5 was found in single nerve fibres distributed mainly in the tunica albuginea. The interstitial cells were heavily stained for LH-receptors and NADPH-diaphorase. In the testes of immunized animals, only single TH-IR nerve fibres, scattered mainly in the tunica albuginea, were observed. Some TH-IR nerve terminals were also encountered in the parenchyma of the organ, where they were always associated with blood vessels. D beta H-IR nerve fibres formed a dense network distributed throughout the testis in association with the capsule, vasculature and interstitium. Some fibres were observed to run between seminiferous tubules. VIP-IR nerve fibres were located in the neighbourhood of blood vessels in the tunica albuginea and parenchyma. Only single VIP-IR nerves were found between seminiferous tubules. Numerous NPY-IR nerve fibres occurred in the tunica albuginea and parenchyma of the organ. SNAP-25-IR and PGP 9.5-IR nerve terminals formed a dense network distributed throughout the testis and many fibres were observed between seminiferous tubules. Interstitial cells were very weakly stained for LH receptors or NADPH-diaphorase.

Complete protection of mice from respiratory syncytial virus infection following mucosal delivery of synthetic peptide vaccines

We have previously shown that intraperitoneal immunization of BALB/c mice with the 14 amino-acid long synthetic peptides G/174-187 and BG/174-187, representing the region 174-187 of the G-glycoprotein from human (H) and bovine (B) respiratory syncytial virus (RSV), respectively, completely protects animals from infection with the corresponding virus. A current goal in vaccine development being the delivery of noninvasive protective antigens via mucosal surfaces, we have evaluated the immunogenicity and protective efficacy of the two peptides when administered to mice by the intranasal (i.n.) route in the presence or absence of the cholera toxin (CT) as a mucosal adjuvant. The two peptides given alone induced the production of RSV-specific circulating IgG, as revealed by ELISA titers of immune sera. When the peptides were administered intranasally with CT, the higher IgG antibody titer which was induced was within the same order of magnitude as that obtained following i.n. immunization with live RSV or intraperitoneal injection with the peptides, thus demonstrating the stimulatory effect of the CT adjuvant. Moreover, although the peptides fail to induce a detectable level of secretory IgA, all animals immunized i.n. with peptide BG/174-187 (plus or minus CT) and all those immunized with peptide G/174-187 mixed with CT were completely resistant to infection by the corresponding virus. To our knowledge, this is the first study reporting that complete protection against a natural pathogen can be elicited by mucosally delivered synthetic peptides. This supports the usefulness of synthetic peptides in prophylactic vaccination.

Development and characterization of an antibody directed to an alpha-N-acetyl-D-galactosamine glycosylated MUC2 peptide

In an attempt to raise anti-Tn antibodies, an alpha-N-acetyl-D-galactosamine glycosylated peptide based on the tandem repeat of the intestinal mucin MUC2 was used as an immunogen. The MUC2 peptide (PTTTPISTTTMVTPTPTPTC) was glycosylated in vitro using concentrated alpha-N-acetylgalactosaminyltransferases activity from porcine submaxillary glands which resulted in the incorporation of 8-9 mol of Ga/NAc. Rabbits and mice developed specific anti-MUC2-GalNAc glycopeptide antibodies and no detectable anti-Tn antibodies. Anti-glycopeptide antibodies did not show reactivity with the unglycosylated MUC2 peptide or with other GalNAc glycosylated peptides. A mouse monoclonal antibody (PMH1) representative of the observed immune response was generated and its immunohistological reactivity analysed in normal tissues. PMH1 reacted similarly to other anti-MUC2 peptide antibodies. However, in some cells the staining was not restricted to the supranuclear area but extended to the entire cytoplasm. In addition, PMH1 reacted with purified colonic mucin by Western blot analysis suggesting that PMH1 reacted with some glycoforms of MUC2. The present work presents a useful approach for development of anti-mucin antibodies directed to different glycoforms of individual mucins.

Immunization with a peptide derived from the G glycoprotein of bovine respiratory syncytial virus (BRSV) reduces the incidence of BRSV-associated pneumonia in the natural host

Previous reports demonstrate that synthetic peptides corresponding to the amino acid region 174-187 of G glycoprotein from subgroups A and B human respiratory syncytial virus (HRSV), containing a Cys-->Ser substitution at position 186, confer complete resistance to immunized BALB/c mice against infection with the respective virus. In this report, we show that a Cys186-->Ser substituted peptide (BG/174-187) representing the corresponding region of the bovine (B) RSV G glycoprotein conferred complete protection of mice against BRSV challenge, suggesting that the 174-187 region of RSV G glycoproteins constitutes a dominant protective epitope which has been maintained throughout evolution. Furthermore, immunization of calves with peptide BG/174-187 efficiently induced the production of antibodies capable of recognizing both the parental G glycoprotein and peptide BG/174-187. Following challenge with live BRSV, although none of the animals were protected from upper respiratory tract disease, there were little or no gross pneumonic lesions in the four peptide-immunized calves. In contrast, moderate to extensive pneumonic lesions were observed in 2 out of 3 calves in the control group. Our results thus suggest that peptide BG/174-187 efficiently prevented BRSV-associated pneumonia in the natural host. The use of this system as a model is quite promising with regard to the development of a human synthetic vaccine.

Specific inhibition of human CYP1A2 using a targeted antibody

The structural similarity of related forms of P450 makes selective immunoinhibition of individual forms notoriously difficult to achieve. We report the use of a targeted antibody to overcome this problem. An antibody was raised against the synthetic peptide, Ser-Lys-Lys-Gly-Pro-Arg-Ala-Ser-Gly-Asn-Leu-Ile, corresponding to residues 291-302 of human CYP1A2. This sequence of human CYP1A2 is located in a similar position to a proinhibitory region previously identified in rat CYP1A1 and CYP1A2. The antibody bound strongly and specifically to CYP1A2 in human hepatic microsomal fraction. Binding was unaffected by denaturation of the protein. The specificity of the antibody was demonstrated by immunoblotting of human hepatic microsomal fraction where a single immunoreactive band was identified at Mr 54,000. The intensity of this band correlated strongly with high-affinity phenacetin O-deethylase activity of the microsomal fractions. In addition, the antibody bound to a single protein at Mr 54,000 in the microsomal fraction of lymphoblastoid cells expressing human CYP1A2, but not to any other recombinant P450 enzyme. CYP1A2-dependent activity (high-affinity phenacetin O-deethylase) of human hepatic microsomal fraction was inhibited >90% by whole antiserum or purified immunoglobulin. This decrease in activity represents complete inhibition of CYP1A2 activity, residual phenacetin O-deethylase activity being due to low-affinity enzymes. In contrast, the antibody, which does not bind to rat CYP1A2, had no effect on CYP1A2-dependent activity (high-affinity phenacetin O-deethylase) of rat hepatic microsomal fraction. The antiserum also had no effect on human hepatic microsomal debrisoquine 4-hydroxylase (CYP2D6) or coumarin 7-hydroxylase (CYP2A6) activities, indicating that inhibition was specific to human CYP1A2. These results demonstrate the importance of the region comprising residues 291-302 of human CYP1A2 in the catalytic activity of this enzyme.

Monoclonal anti-fosB antibody specific for predetermined, nonstructural region of the fosB protein

Comparison of the primary structures and theoretical prediction of the potential antigenic determinant of the deduced Fos proteins reveals the presence of a nonstructural and hydrophilic region juxtaposed to the leucine zipper and nonconserved among the Fos protein family. To develop monoclonal anti-peptide antibodies capable of distinguishing all Fos-proteins, synthetic peptides specific for the mentioned predicted region were synthesized manually by the "tea-bag" method. Immunization of Balb/c mice with fosB-related synthetic peptide BSA gave rise to mouse hybridoma cell line K21 (IgG1, kappa) secreting highly specific antibodies against corresponding human fosB protein. Fine mapping of the MAb K21 indicated that the minimal epitope essential for the recognition is the sequence GPGPLAE.

Subgroup specific protection of mice from respiratory syncytial virus infection with peptides encompassing the amino acid region 174-187 from the G glycoprotein: the role of cysteinyl residues in protection

We identified subgroup specific protective epitopes represented by the amino acid regions 174-187 and 171-187 of the G glycoproteins from respiratory syncytial virus (RSV), subgroups A and B. Mice immunized with coupled synthetic peptides corresponding to either the region 174-187 containing a Cys186-->Ser substitution or to the native region 171-187 were completely resistant to RSV infection but only to the respective virus. The protective activities of the peptides 174-187 were dependent on the Cys186-->Ser substitution. In addition, a recombinant protein representing the region 125-203 of the A subgroup G glycoprotein expressed in Escherichia coli was capable without further treatment to completely protect animals against RSV subgroup A infection. We show that the combinations of cysteinyl residues (positions 173, 176, 182, and 186) retained within either synthetic peptides or the recombinant protein G125-203 greatly influenced their protective activities. This indicates that the region 171-187 is essential for the protection conferred by the G125-203 protein. Furthermore, our results strongly suggest that the peptides' and recombinant protein's potencies are a function of a loop-like structure which is stabilized by intramolecular disulfide linkages between Cys176-Cys182 and Cys173-Cys186. This is further supported by the observation that chemical blocking of the sulfidryl groups in synthetic peptides completely eliminated their protective activity.

Binding of site-directed monoclonal antibodies to an epitope located in the A/B region (amino acids 140-154) of human estrogen receptor-induced conformational changes in an epitope in the DNA-binding domain

The interactions of estrogen receptor (ER) with monoclonal antibody (Mab) F9, developed against a synthetic 30-mer hybrid oligopeptide, were determined in the presence or absence of Mab NMT-1, raised against 15-mer peptide from the N-terminal A/B region (amino acids 140- 154) or Mab 213, raised to a peptide AT3 in the DNA-binding domain (amino acids 247-263). Mab F9 bound ER and formed a complex sedimenting at the approximately 11S region of the gradients. Mabs 213 and NMT-1 bound ER and formed complexes sedimenting at approximately 7S and 9S, respectively. Preincubation of ER with Mab 213, followed by reincubation with Mab F9, resulted in a complex sedimenting at the approximately 11S region of the gradients. Similarly, preincubation of ER with Mab NMT-1 followed by reincubation with Mab F9 also produced an approximately 11S complex on the gradients. These observations suggest that binding of Mab F9 to ER induced conformational changes causing the release of Mab 213 and Mab NMT-1 from ER. Furthermore, binding of Mab NMT-1 to the A/B region of ER also produced conformational changes causing the release of Mab 213 from its epitope in the DNA-binding region. These results indicate that binding of Mab F9 and Mab NMT-1, with epitopes located within amino acids 140-154 of the A/B region of ER, induced conformational changes in the DNA-binding domain, as determined by the inability of Mab 213 to remain bound to its epitope. These data further suggest that the DNA-binding region is sensitive to conformational changes induced in the native protein.

Use of macromolecular assemblies as expression systems for peptides and synthetic vaccines

The past decade has witnessed the development of numerous systems for the presentation of antigens on the surface of self-assembling macromolecules. Although the sites for insertion were initially chosen empirically, the determination of the three-dimensional structures of a number of carrier macromolecules has enabled structure-based insertional mutagenesis to be used increasingly. Furthermore, it is now feasible to determine the structure of an inserted sequence as presented in a heterologous environment, making it possible to correlate the detailed structure of a peptide with its immunological properties.

Structure-based design of peptide presentation on a viral surface: the crystal structure of a plant/animal virus chimera at 2.8 A resolution

BACKGROUND

We employed a genetically engineered icosahedral plant virus, cowpea mosaic virus (CPMV), as an expression and presentation system to display a 14 amino acid linear antigenic epitope found in a capsid protein of human rhinovirus 14 (HRV14).

RESULT

Gram quantities of the CPMV/HRV 14 chimera were made in plants and purified particles were crystallized in a form isomorphous with wild-type CPMV. The 2.8 A resolution structure of the chimera shows that the inserted loop is well ordered and that if the loop were intact, a phenylalanine residue of CPMV would be placed in a hydrophilic environment. The resultant strain may make the loop an attractive substrate for endogenous plant proteases, as roughly 80% of the inserted polypeptides are cleaved, allowing the phenylalanine to be partially buried. Altering the phenylalanine to an arginine could relieve the stress, reducing the propensity for cleavage and increasing the likelihood that the peptide will assume a structure closely similar to its structure in HRV14.

CONCLUSIONS

Successful crystallization of other CPMV chimeras in forms isomorphous with the native virus suggests that this is a viable system for structure-based design of peptide presentation.

Peptide vaccine against canine parvovirus: identification of two neutralization subsites in the N terminus of VP2 and optimization of the amino acid sequence

The N-terminal domain of the major capsid protein VP2 of canine parvovirus was shown to be an excellent target for development of a synthetic peptide vaccine, but detailed information about number of epitopes, optimal length, sequence choice, and site of coupling to the carrier protein was lacking. Therefore, several overlapping peptides based on this N terminus were synthesized to establish conditions for optimal and reproducible induction of neutralizing antibodies in rabbits. The specificity and neutralizing ability of the antibody response for these peptides were determined. Within the N-terminal 23 residues of VP2, two subsites able to induce neutralizing antibodies and which overlapped by only two glycine residues at positions 10 and 11 could be discriminated. The shortest sequence sufficient for neutralization induction was nine residues. Peptides longer than 13 residues consistently induced neutralization, provided that their N termini were located between positions 1 and 11 of VP2. The orientation of the peptides at the carrier protein was also of importance, being more effective when coupled through the N terminus than through the C terminus to keyhole limpet hemocyanin. The results suggest that the presence of amino acid residues 2 to 21 (and probably 3 to 17) of VP2 in a single peptide is preferable for a synthetic peptide vaccine.

Short synthetic peptides exploited for reliable and specific targeting of antibodies to the C-termini of cytochrome P450 enzymes

An antibody was raised against a synthetic peptide (Ser-Glu-Asn-Tyr-Lys-Asp-Asn) corresponding to residues 290-296 of the cytochrome P450 enzyme, CYP1A2, of both rat and mouse. A cysteine residue attached to the N-terminus of the peptide during synthesis allowed coupling in a specific orientation via the thiol group to the carrier protein, keyhole limpet haemocyanin. Antiserum raised in rabbits bound specifically to CYP1A2 in the rat and mouse. To determine those amino acid residues involved in binding of the antibody, related peptides of various lengths were synthesised and the binding of the antibody was determined by an enzyme-linked immunosorbent assay. These studies show that the minimum epitope is the C-terminal tripeptide sequence, Lys-Asp-Asn. Other than in rat and mouse CYP1A2, this tripeptide is found as an internal sequence in a large number of proteins including bovine fibronectin, chicken gizzard myosin heavy chain, and the P450 enzymes, rabbit CYP3A6 and human CYP3A4, but the antibody did not bind to any of these proteins. However, the antibody did bind to yeast glucose-6-phosphate dehydrogenase in which the tripeptide sequence is the C-terminus. Antibodies raised against a truncated peptide (Tyr-Lys-Asp-Asn), representing the C-terminal half of the peptide, also bound to glucose-6-phosphate dehydrogenase, but failed to bind to CYP1A2; thus although the C-terminal region of the peptide 290-296 is strongly immunogenic, it appears that it is not this population of antibodies that binds to CYP1A2. As antibodies were found to bind strongly to the C-terminus of glucose-6-phosphate dehydrogenase, the C-termini of proteins as targets for anti-peptide antibodies were investigated further by immunising rabbits with four 5-residue peptides which represent the C-termini of the P450 enzymes, CYP1A1, CYP1A2, CYP2E1 and CYP2A6. The peptides were coupled to keyhole limpet haemocyanin through their N-termini via cysteine residues added to the sequences. All four antisera bound specifically to their respective target proteins, as demonstrated by immunoblotting using hepatic microsomal fractions from rat, rabbit and human. It is suggested that this method of antibody production could be of general use for the reliable production of antisera against proteins where their sequence at the C-terminus is known, and such antibodies can be highly specific as they do not bind to internal sequences.

Lesions in the hypothalamus after active immunisation against GnRH in the pig

The terminals of the hypothalamic gonadotrophin hormone-releasing hormone (GnRH) neurons are located within the median eminence and thereby extend beyond the protection of the blood-brain barrier. Thus, these terminals may be subjected to direct autoimmune action in animals that are actively immunised against GnRH. Boars (male pigs) (n = 108) were actively immunised against GnRH by two successive injections with synthetic GnRH, covalently coupled to KLH and dissolved in CFA or IFA. They were killed at 26 weeks of age. Immunised boars were selected on the basis of the resultant testes size, which indicates the effectiveness of the immunisation. The hypothalami of 25 selected animals were studied by histological and immunocytochemical techniques and compared with the hypothalami of three sham- and nine control animals. In the immunised animals, changes in the GnRH system had taken place. These comprised dystrophy of the perikarya and a sharp decrease of the GnRH immunocytochemical reactivity in the terminals within the median eminence. In addition, various degrees of inflammatory reactions were present, particularly within the median eminence. These consisted of tissue disruption by edema, collapse of the capillaries, fibrosis and infiltration with fibroblasts. In addition, accumulations of neurosecretum within the median eminence in combination with hypertrophy of magnocellular neurons within the hypothalamus were present. The reactions were restricted to the median eminence and did not involve other neurohemal organs or other parts of the hypothalamus. A correlation could be established between the incidence of the lesions and the effectiveness of the GnRH autoimmunity (as indicated by the size and endocrine function of the gonads and the anti-GnRH titres). Changes in extra- and intracellular IgG immunocytochemical reactivity within the median eminence indicated the involvement of IgG. The effects were absent from control and sham vaccinated animals and after vaccinations with other compositions of the vaccine. Thus, hypothalamic lesions have been observed in this selected group of animals, vaccinated against GnRH with this particular vaccine.

Antigenic analysis of bean pod mottle virus using linear and cyclized synthetic peptides

The antigenic structure of the comovirus bean pod mottle virus (BPMV) was studied using synthetic peptides selected on the basis of the exposed location of certain regions of the viral protein. Three regions of domain A, four regions of domain B and two regions of domain C of BPMV coat protein were studied. Each of four regions were synthesized in the form of linear and cyclized peptides while the others were synthesized as linear peptides only. The peptides were tested for their ability to be recognized by antibodies directed against BPMV. The peptides were also used for producing rabbit antisera, which were tested for their ability to react with various BPMV antigens as well as with the linear and cyclized peptides. All the peptides were found to correspond to epitopes of BPMV coat protein. Several of the antigenic sites of BPMV located on exposed loops of the coat protein occupy positions which correspond to known epitopes in the structurally related picornaviruses. Only in some cases did cyclization sufficiently improve the level of conformational mimicry between peptides and the viral protein to allow cross-reactions between them to be observed.

Identification of the epitope of an anti-peptide antibody which binds to CYP1A2 in many species including man

An anti-peptide antibody was raised against the sequence Thr-Gly-Ala-Leu-Phe-Lys-His-Ser-Glu-Asn-Tyr-Lys which occurs at positions 283-294 in the rat cytochrome P450 enzyme CYP1A2. Compared with its binding to the peptide used for immunization, the antibody bound with only slightly reduced affinity to the truncated peptides Thr-Gly-Ala-Leu-Phe-Lys-His-Ser and Leu-Phe-Lys-His-Ser. However, binding to the peptide Ser-Glu-Asn-Tyr-Lys-Asp-Asn, which overlaps with the C-terminal region of the immunizing peptide, was very low. Thus, a major epitope for the anti-peptide antibody is Leu-Phe-Lys-His-Ser, which corresponds to a region of CYP1A2 that is conserved in many species. The antibody was tested by immunoblotting for its ability to bind to hepatic microsomal fractions from a number of species. Where possible animals were treated with compounds which induce CYP1A2 and the results compared with those with untreated animals. It was found that the antibody bound to rat, mouse, rabbit, hamster, guinea pig, pig, marmoset monkey and human CYP1A2. No evidence was found for binding to dog CYP1A2. The region corresponding to the major epitope at residues 286-290 of rat CYP1A2 was identical in mouse, hamster, rabbit and human CYP1A2. The sequence of marmoset and guinea pig CYP1A2 are not known but are predicted to be very similar to the sequence in the rat. The lack of binding of the antibody to dog CYP1A2 may be explained by two differences in this region compared with rat CYP1A2. Maximum inhibition of CYP1A2 activity by this antibody, as measured by high-affinity phenacetin O-deethylase activity, was 20%. This is in contrast to a previously described anti-peptide antibody directed to an adjacent region which caused 65% inhibition of this activity. Thus, the edge of an inhibitory region on the surface of cytochrome P450 has been identified. The ability of the antibody to bind to CYP1A2 from a number of animals should make this antibody of use for studying the levels of CYP1A2 apoprotein in many species.

Monoclonal antipeptide antibodies: affinity and kinetic rate constants measured for the peptide and the cognate protein using a biosensor technology

The interaction of antipeptide antibodies with the corresponding peptide and the cognate protein has been compared using a novel biosensor technology (BIAcore, Pharmacia). The peptide corresponds to residues 110-135 of the coat protein of tobacco mosaic virus, known to encompass an alpha-helical region reactive with antiprotein antibodies. A panel of 33 monoclonal antibodies raised against the peptide was studied and the epitope recognized by these antibodies was determined by the pepscan method. Further discrimination between the antibodies was performed by measurements of association and dissociation kinetic constants. Several antibodies showed an heterogeneous binding profile when reacting with the 25 residue long peptide but not with a shorter 10 residue peptide suggesting that they recognized different conformational states in the longer peptide. Equilibrium affinity constants were calculated for five of the antibodies and were found to be 10-50 times higher for the peptide than for the protein, the difference being caused mainly by a lower association rate constant.

An inhibitory monoclonal anti-protein antibody and an anti-peptide antibody share an epitope on rat cytochrome P-450 enzymes CYP1A1 and CYP1A2

A monoclonal antibody, 12/2/3/2, which was raised against purified rat CYP1A1 recognises specifically rat and mouse CYP1A1 and CYP1A2, but not any cytochrome P-450 present in hepatic microsomal fractions from rabbit, guinea pig, hamster or human. By comparing the primary sequences of cytochromes P-450 to which 12/2/3/2 does and does not bind, 10 possible locations for its epitope were found. Of these, one was extremely hydrophilic and, hence, predicted to be the most antigenic in the native protein. An antibody was produced against the synthetic peptide corresponding to this region (Gly-Arg-Asp-Arg-Gln-Pro-Arg-Leu: residues 356-363 and 350-357 of rat CYP1A1 and CYP1A2, respectively). The antibody bound to rat, mouse and hamster CYP1A1 and to rat and mouse CYP1A2, but did not bind to any protein present in hepatic microsomal fractions from the rabbit, guinea pig or human. The binding of the anti-peptide antibody to CYP1A1 or CYP1A2 was partially antagonised by the monoclonal antibody. However, whereas the monoclonal antibody inhibited both CYP1A1- (aryl hydrocarbon hydroxylase) and CYP1A2-(high-affinity phenacetin O-deethylase) dependent monooxygenase activity, the anti-peptide antibody was without effect on these activities. Antigen denaturation by 8 M urea or 0.05% (w/v) SDS had no effect on binding of the anti-peptide antibody to cytochrome P-450, whilst binding of the monoclonal antibody was reduced by more than 1000-fold. The anti-peptide antibody partially antagonised the binding of 12/2/3/2 to urea-denatured but not native cytochrome P-450. These data suggest that whilst the complete binding site for the monoclonal antibody is discontinuous, sufficient of the epitope is linear, so that when the antigen is denatured the monoclonal antibody is still able to bind and this binding is antagonised by the anti-peptide antibody. However, inhibition of catalytic activity by the monoclonal antibody must require binding to discontinuous residues.

Comparison and fine mapping of both high and low neutralizing monoclonal antibodies against the principal neutralization domain of HIV-1

Monoclonal antibodies raised against viral lysate of HIV-1 (strain LAV-1) and against recombinant gp 160 of HIV-1 (strain HTLV IIIB) which neutralized HIV-1 in a type specific manner were mapped with the aid of peptides (Pepscan analysis). Each of these monoclonal antibodies bound to peptides located on the principal neutralizing domain (PND) of HIV-1. We found that the antigenic sites of the MAbs described in this paper are represented by linear peptides of at least 10 amino acids long. The affinity of the MAbs is high for these peptides and in the same order of magnitude as for native gp 160. The fine mapping of the epitopes may reflect structural features of the PND, for instance which amino acid side chains are exposed and which are buried in the protein. Furthermore the fine mapping of the epitopes explained the HIV type-specific neutralizing activity of the MAbs. Antibodies that bound to the tip of the loop (amino acids QRGPGRAF) have a higher neutralizing activity than antibodies that bound to amino acids towards the N-terminal side of the loop (amino acids KSIRI). Furthermore, MAbs that bound to virtually the same amino acids on the tip of the loop (amino acids IQRGPGRAF and RGPGRAFV) had different neutralizing activities due to different affinities for native gp 160. These data reveal that neutralizing activity not only is determined by the affinity of an antibody to the neutralizing site but also by its fine binding specificities to the V 3 loop of gp 120.

Protection of BALB/c mice from respiratory syncytial virus infection by immunization with a synthetic peptide derived from the G glycoprotein

A synthetic peptide homologous to amino acids 174-187 of the G glycoprotein of the A2 strain of human respiratory syncytial (RS) virus (G/174-187) was shown to induce protection from live virus challenge of BALB/c mice after immunization with three doses of 50 micrograms of peptide coupled to keyhole limpet hemocyanin. Immunized mice showed high levels of circulating RS-specific antibodies as detected by ELISA assay; however, no neutralizing antibodies were found. Moreover, an important short-term cytotoxic T-cell response was observed with lymphocytes isolated from the lungs but not from the spleen of immunized mice. This response was lost 24 weeks after immunization; however, mice remained protected against challenge with live RS virus. In addition, a monoclonal antibody that specifically binds to peptide G/174-187 was found efficient in conferring passive protection from challenge: this data further supports our results on the importance of the 174-187 region in protection. Another peptide, spanning amino acids 144 to 159, was shown to induce neutralizing antibodies but did not confer protection.

Identification of a functionally conserved surface region of rat cytochromes P450IA

A region of rat cytochrome P450IA1 at residues 294-301 (Gln-Asp-Arg-Arg-Leu-Asp-Glu-Asn), equivalent to a proinhibitory region of cytochrome P450IA2, was identified by sequence alignment. Anti-peptide antibodies were successfully raised when the peptide was coupled through either its N- or its C-terminus to carrier protein, but no antibodies were produced against the so-called multiple peptide antigen, which consisted of eight copies of the peptide attached through its C-terminus to a synthetic base. Both of the anti-peptide antibodies bound specifically to cytochrome P450IA1 in the rat, as shown by e.l.i.s.a. and immunoblotting. They inhibited microsomal aryl hydrocarbon hydroxylase activity and the mutagenic activation of 2-acetylaminofluorene (these reactions are catalysed by cytochrome P450IA1), but not high-affinity phenacetin O-de-ethylation activity, which is catalysed by cytochrome P450IA2. However, there was differences in the properties of the two antisera in their binding to cytochromes P450IA1 in species other than the rat, their relative binding to the multiple peptide antigen, the yield of antibody following affinity purification using peptide coupled through its N-terminus to CNBr-activated Sepharose, and the binding of the purified preparations to N- and C-terminal-coupled peptide conjugates. These observations indicated that the antibodies were directed to the region of the peptide opposite to the end which was coupled to the carrier protein. Nevertheless, both of the antibody preparations bound equally well to the target cytochrome P450, thus indicating that, in the native protein, the whole of the peptide region is exposed on the surface of cytochrome P450IA1 and is available for binding by the antibodies. The role of this region appears to be the same in both cytochromes P450IA1 and P450IA2, despite the difference in its primary structure in the two cytochromes P450.

Heterotypic passive protection induced by synthetic peptides corresponding to VP7 and VP4 of bovine rotavirus

We have evaluated the potential of two peptides derived from highly conserved regions of rotavirus outer capsid proteins (VP7 and VP4) to act as a rotavirus vaccine. The capacity of peptides coupled to rotavirus VP6 spherical particles to provide passive protection in a murine model was compared with the protection induced by peptide-keyhole limpet hemocyanin (KLH) conjugates. Female mice were immunized a total of three times before and during pregnancy. Suckling mouse pups were challenged at 7 days of age with either homologous or heterologous rotavirus serotypes. The efficacy of vaccination was determined by analyzing the clinical symptoms and measuring xylose adsorption in the intestine. In this model the VP4 peptide-VP6 conjugate provided protection equal to that obtained using bovine rotavirus (BRV) as the immunogen. The VP7 peptide-VP6 conjugate provided slightly less protection than the VP4 peptide-VP6 conjugate. A mixture of the VP4 peptide-VP6 and VP7 peptide-VP6 conjugates provided better heterologous protection than immunization with BRV. In contrast, KLH-conjugated peptides provided only partial protection. The significance of a synthetic-peptide-based rotavirus vaccine in the prevention of rotavirus infections is discussed.

Immunological mapping of fine molecular surface structures of citrate synthase enzymes from different cell types

Citrate synthase (EC 4.1.3.7), which is present in all living organisms as a key enzyme in aerobic energy metabolism, is one of the most highly phylogenetically conserved enzymes known in terms of its primary and active site structure. However, in terms of other parameters such as in vitro stability, tolerance to changes in pH, degree of self-polymerization, etc., citrate synthases from different sources are markedly different. These divergences can be observed even between isoforms of the enzyme within the same species. Data documenting these diversities suggest that a high degree of difference in tertiary structures may occur. Therefore, the surface profiles of citrate synthase enzymes from yeast, pig, rat, tomato and Escherichia coli were investigated with immunological methods using monoclonal antibody families generated against either pig citrate synthase (alpha-PCS) or yeast citrate synthase-2 (alpha-YCS-2). A high degree of homology of enzyme epitopes was detected on the mitochondrial citrate synthases originating from yeast, tomato, pig and rat cells. Major differences were found between the hexameric citrate synthase originating from E. coli compared with those dimeric forms prepared from eukaryotic cells. Only modest similarities were detected between the highly homologous peroxisomal and mitochondrial yeast citrate synthases. Furthermore, a point mutation of one of the catalytic residues (H274R on recombinant pig and H313R on yeast enzyme) of mitochondrial citrate synthase (CS-1) resulted in a significant increase in immunological similarity with the peroxisomal isoenzyme (CS-2). These findings are discussed in terms of the possible mechanism of evolution of CS-2 in yeast.

Epitope prediction and confirmation for the human androgen receptor: generation of monoclonal antibodies for multi-assay performance following the synthetic peptide strategy

The human androgen receptor (hAR) is an important regulatory protein particularly in male sexual differentiation. The investigation of hAR functionality has been hampered by the lack of AR specific monoclonal antibodies recognizing the functional domains of the receptor. Therefore production of high affinity mono-specific polyclonal (PAbs) and monoclonal antibodies (MAbs) directed to the hAR was initiated following the synthetic peptide (SP) strategy. Five hAR specific peptides were selected on the basis of their predicted antigenic properties avoiding homology with other steroid hormone receptors. Peptide specific polyclonal antisera were obtained following selected immunization protocols. Mono-specific polyclonal antibody responses were elicited to all peptides in mice and rabbits. Crossreactivity of the peptide specific antisera with the native hAR in various biochemical assays was observed with two out of five peptides. Peptide SP61 (hAR residues 301-320) was used for the generation site-directed MAbs specific for the hAR. Specificity for the hAR was established by immunoprecipitation, immune-complex density gradient centrifugation and immunohistochemistry on human prostate tissue sections. The multi-assay performance of the selected high affinity antibodies proved the usefulness of the straight forward peptide approach and opens a wide field of possible biochemical and physiological investigations into questions related to androgen action.

Structural characterization of the second major cross-reactive idiotype group of human rheumatoid factors. Association with the VH4 gene family

Rheumatoid factors (RF) are the most common type of functional antibodies among naturally occurring human monoclonal IgM proteins. A large subset of these autoantibodies use structurally homologous light chains of the kappa III subgroup, which bear the 6B6.6 cross-reactive idiotype (CRI). Although antibody binding activity requires both heavy and light chains, information about the heavy chains used by these autoantibodies is limited. To investigate these proteins, the murine monoclonal antibodies, 5-14 and 6-10, were generated by immunization with the heavy chains of the 6B6.6 CRI-positive RF, COR and LEW. These antiidiotypic antibodies reacted with 8 of 11 autoantibodies that coexpressed the 6B6.6 CRI. All 8 RF had heavy chains from the VH4 gene family, as assessed by reactivity with a VH4-specific primary sequence-dependent antibody. The same RF were also identified by the previously described murine monoclonal antiidiotype, LC1. Further experiments revealed that the LC1 antibody delineates a subfamily of VH4 heavy chains that is preferentially used in kappa III-6B6.6 CRI-positive IgM-RF. The cumulative data suggest that 13-22% of RF express both the kappa III-6B6.6 and VH4-LC1 CRI. These findings document that RF autoantibody activity requires specific VL-VH pairing, and that a subset of idiotypically related VH4 heavy chains is commonly expressed in disease-associated monoclonal IgM-RF.

An improved conjugation method for controlled covalent coupling of synthetic peptides to proteins using glutaraldehyde in a dialysis method

Controlled and efficient conjugation of synthetic peptides to proteins, for use in immunization or in assay procedures, is a prerequisite for the immunological applications of synthetic peptides. This study describes a new method of conjugating synthetic peptides to proteins in such a way that no homopolymers of synthetic peptides or proteins occur. To achieve this, the protein is first activated with glutaraldehyde and subsequently excess glutaraldehyde is removed. Then coupling of the synthetic peptide to the activated protein occurs while subsequently the surplus reactive glutaraldehyde groups on the protein are blocked with lysine. Excess free peptide and lysine is then removed by dialysis. This improvement not only results in better defined conjugates when compared to classical glutaraldehyde coupling, but also in the consumption of smaller amounts of synthetic peptide during conjugate formation. When used for immunization we obtained similar and sometimes even better responses with the glutaraldehyde based conjugates than with succinimidyl (MBS) conjugates of the same peptides. The performance of the modified conjugates in ELISA procedures, immunization and immunocytochemistry suggests that they are superior to conjugates formed by classical glutaraldehyde coupling.

Immunological cross-reactivity to laboratory-produced HPV-11 virions of polysera raised against bacterially derived fusion proteins and synthetic peptides of HPV-6b and HPV-16 capsid proteins

Polysera raised in rabbits to bacterially derived fusion proteins and synthetic peptides of the L1 and L2 ORFs of HPV-6b and -16 were tested for cross-reactivity to laboratory-produced infectious HPV-11 virions. The polysera were analyzed in a series of five different immunological assays including immunoperoxidase staining of the koilocytotic nuclei in sections of formalin-fixed, paraffin-embedded as well as fresh frozen sections of HPV-11 experimental condylomas generated in the athymic nude mouse xenograft system, ELISA, Western blots, and neutralization of infectious HPV-11 virions. ELISA and Western blot assays were used to determine whether the polysera identified external or internal epitopes on HPV-11 virions, and whether there was cross-reactivity to BPV-1 or laboratory-produced CRPV virions. Seven of a total of 12 sera were positive for reactivity to HPV-11 in one or more assays, but none of the reactivity was directed to external epitopes on the intact virions as determined by ELISA. None of the L1 products generated group-specific antigen (GSA) antisera including a synthetic peptide spanning the GSA site. The combination of assays clearly demonstrated that apparent false positive and false negative reactivities of different antisera were obtained for each assay system tested. Thus, no single assay could be used reliably to determine the true antiviral reactivity of a given polysera.

Structural characterization of human monoclonal cold agglutinins: evidence for a distinct primary sequence-defined VH4 idiotype

Cold agglutinins that bind the developmentally regulated I red cell determinant occur naturally among human monoclonal IgM proteins. These autoantibodies are known to use light chains that derive mainly from the minor kappa III (kappa III) variable region subgroup. The kappa III subgroup is also highly expressed in monoclonal rheumatoid factors. However, while most monoclonal rheumatoid factors use structurally homologous heavy chains that derive from the VH1 family, information regarding the structure of the cold agglutinin heavy chains remains fragmentary. We demonstrate here that the kappa III cold agglutinin autoantibodies exclusively use heavy chains that derive from the VH4 family. Furthermore, these autoantibody heavy chains all express the same primary sequence-defined idiotype, corresponding to the second hypervariable region. These data indicate that cold agglutinins use a remarkably homogeneous subset of heavy chain variable regions. Moreover, unique patterns of preferential VH and VL pairing clearly distinguish the anti-I cold agglutinins from all other known monoreactive autoantibodies.

Peptide component vaccine engineering: targeting the AIDS virus

Most of the successful vaccines developed to date induce protective immunity resembling that produced by natural infection. HIV infection does not induce protective immunity. Thus, previously successful approaches based on live- or killed-virus preparations may not yield an effective and safe AIDS vaccine and many feel that a more highly engineered vaccine will be required. Synthetic peptides represent extremely powerful tools for vaccine research and construct optimization. The theory and practice of vaccine engineering using synthetic peptide components is reviewed with special emphasis on progress towards development of a vaccine for AIDS.

Development and characterization of monoclonal antibodies with specificity for metallic radioisotope chelators linked to antibodies and other proteins

Monoclonal antibodies with specificity for the diethylenetriaminepentaacetic acid (DTPA) portion of the GYK-DTPA (glycyl-tyrosyl-lysine-DTPA) linker structure used to chelate metals to immunoglobulins have been prepared. A significant proportion of these antibodies were lambda light chain isotype. Competition assays demonstrated that DTPA, rather than GYK, was the binding site of the antibodies tested. These monoclonal antibodies should be useful reagents for use in assays specific for the presence of the common linker structure used to chelate metallic radioisotopes to monoclonal antibodies. The antibodies tested did not discriminate between chelated and unchelated DTPA.

Development and application of synthetic peptides as vaccines

Vaccination against bacterial and viral diseases has been one of the major achievements in medicine and immunology since the beginning of this century. Extensive vaccination programs have been able to control or, in the case of smallpox, virtually wipe out some of the most dangerous infectious diseases e.g. poliomyelitis, measles, whooping cough, diphtheria and tetanus. However, as this success has been limited mainly to the developed, affluent countries, infectious diseases still remain the worlds largest health problem. Furthermore, vaccines against human parasites are non-existent. Recent advances in immunology and molecular biology including recombinant DNA technology have provided the basis for new approaches to vaccine development.