Paramyxovirus membrane protein enhances antibody production to new antigenic determinants in the actin molecule: a model for virus-induced autoimmunity.

Paramyxovirus membrane (M) protein specifically binds to cellular actin but not to bovine serum albumin or myoglobin, as determined by affinity chromatography and enzyme-linked immunosorbent assay. The binding site for M protein on actin is different from the binding sites for antiactin antibodies. The interaction of M protein with actin resulted in production of antibodies to several new antigenic sites on the actin molecule. Five rabbits immunized with actin alone produced antibodies against the N-terminal sequence (residues 1 to 39). Another five rabbits immunized with a mixture of M protein and actin produced antibodies against a C-terminal fragment and a central region as well as the N-terminal fragment. By immunoblotting with proteolytic fragments of actin, the new antigenic sites were located between amino acid residues 40 to 113, 114 to 226, and 227 to 375. Antisera taken from some patients with recent measles virus infections demonstrated antiactin antibodies to sites other than the N-terminal fragment of actin (amino acids 1 to 39). The interaction of paramyxovirus M protein with actin and the subsequent production of antibodies to new antigenic sites may serve as a model for one of the mechanisms of virus-induced autoimmunity.     

Determination of antibody affinity by using antigenic and antibody immunosorbents

To determine the affinity of the active centers of antibodies, cellulose immunosorbents for antibodies and antigens have been used. The fixation of serum proteins on the sorbent, the interaction of fixed antibodies with a monovalent antigen and the graphic analysis of the results thus obtained allows one to assess not only the concentration of the effective active centers on the sorbent, but also all known characteristics of antibody affinity: the average association constant K0, the common association constant Kt, the geometric association constant Kg, the average association constants which determine the affinity of different antibody groups. The use of antigenic immunosorbent permits one to determine the value of the average internal association constant K0. The determination of antibody affinity in hyperimmune antiplague sera by means of immunosorbents and red blood cells coated with capsular antigen has resulted in obtaining similar values of affinity indices.     

Use of an affinity chromatography method for isolating monospecific Salmonella antibodies

Obtaining antibodies to individual components of Salmonella antigenic complex is highly important for investigations aimed at the study of the antigenic structure of bacteria, their serological identification and the development of diagnostic preparations. The method of obtaining antibodies by the oxidation of Salmonella antigens with sodium periodate and creating immunosorbents based on these antibodies with subsequent affinity chromatography has been developed. Monospecific antibodies thus obtained (O2, O4, O9) have been studied and used as monospecific preparations in the agglutination test, the immunofluorescence test and the immunosorbent assay. The development of methods for stabilizing these preparations, thus ensuring their wide practical use, may be of interest.     

Monoclonal antibodies specific for different regions of human apolipoprotein A-I. Characterization of an antibody that does not bind to a genetic variant of apoA-I (Glu----136 Lys)

Three monoclonal mouse hybridoma antibodies, designated 2AI, 4AI, and 5AI, specific for human plasma apolipoprotein A-I (apoA-I) were characterized. In an enzyme-linked immunosorbent assay (ELISA) each of the antibodies reacted with purified apoA-I and with A-I in normal human serum. Immunoblotting of apoA-I subjected to isoelectric focusing revealed that the three antibodies reacted with all the charge isomorphs of apoA-I and with proapoA-I. Using a solid phase competitive displacement assay, the antigenic determinant for antibody 5AI could be localized to cyanogen bromide fragment 3 of apoA-I (residues 113-148), while the epitope for antibody 4AI resided in cyanogen bromide fragment 4. Dot blot experiments and data obtained by the competitive displacement assay revealed that antibody 2AI reacts with high affinity with CNBr fragment 2 but that it also reacts with lower affinity with fragments 1 and 4. The antibody 5AI did not bind to a genetic variant of apoA-I (Glu----136 Lys), demonstrating that the substitution of a single amino acid in human apoA-I can cause the loss of an antigenic determinant.     

Method of purification of glucose oxidase by means of affinity chromatography on immunoabsorbent]

The possibility to purify glucose oxidase from Penicillium vitale on immunosorbent containing specific antibodies to the enzyme covalently bound with Sepharose 4B is studied. The method of affinity chromatography was applied, beside routine methods of fractionating blood serum proteins, to isolate specific antibodies from antiserum of rabbits immunized with glucose oxidase. Immobilized on Sepharose glucose oxidase was used as biospecific sorbent. Specific antibodies to the enzyme were isolated using chromatograpy of gamma-globulins mixture followed by protein desorption from the column with 1 M NaC1 and 3% glucose. Antibodies were immobilized by their covalent binding to activated Sepharose. The immunosorbent obtained was used to purify low active preparation of glucose oxidase by means of affinity chromatography under conditions worked out for the antibodies isolation. The enzyme was eluted from the column with 1 M NaC1 (pH 3.0) containing 3% glucose. 5-Fold purified enzyme preparation was isolated.     

Efficacy of protein A-HRP in an immunological study of black rockfish (Sebastes schlegeli Higendorf) humoral immune responses

The efficacy of protein A-horse radish peroxidase (HRP), as compared to that of mouse polyclonal antibody raised against purified Ig, in detection of black rockfish (Sebastes schlegeli Higendorf) immunoglobulin (Ig) was examined. Protein A affinity chromatography successfully purified Ig from black rockfish serum; the purified-Ig could be visualised as two protein bands (MW 70 and 25kDa) following resolution with sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. In SDS-PAGE immunoblot profiles of the purified-Ig, the mouse polyclonal antibody recognised both the light chain and heavy chains of rockfish Ig, whereas protein A-HRP immunostained only the heavy chain of rockfish Ig. These results suggest that protein A-HRP may be used to detect rockfish antibody-antigen complexes in immunoassays. In a 2-DE immunoblot assay for exploring antigenic profiles of Lactococcus garvieae KG9408, protein A-HRP successfully detected specific antibodies to antigenic proteins of L. garvieae in the rockfish Ig. In addition, enzyme linked immunosorbent assay (ELISA) showed a high correlation between the results obtained for positivity of L. garvieae when protein A-HRP and the mouse polyclonal antibody-was used to analyse samples from 25 diseased rockfish. These results collectively indicate that protein A-HRP has a high affinity for Ig, and may be useful for new investigations into the humoral immune responses of rockfish.     

Molecular and antigenic nature of isolated Sm

The Sm antigen was isolated and purified from calf thymus nuclear extract by affinity chromatography. The affinity columns were made with serum antibodies from an SLE patient or an anti-Sm monoclonal antibody derived from a hybridoma cell line. Proteins eluted from these two columns had m.w. of 58,000 and 35,000 by SDS polyacrylamide gel electrophoresis. The natural conformation of this antigen appears to be 95,000 in m.w. with the 58,000 particle containing the Sm antigenic determinant. The affinity column-purified antigen detected by the human anti-Sm antibodies is also recognized by anti-Sm antibodies in murine lupus serum, as shown by solid-phase radioimmunoassay. This study 1) demonstrates the molecular and antigenic nature of the Sm antigen and 2) compares the anti-Sm binding capabilities of antibody populations present in sera from SLE patients and from MRL lpr/lpr mice.     

Affinity chromatography of human anti-dextran antibodies isolation of two distinct populations

Affinity chromatography is a very efficient method for antibody purification. Two affinity chromatography supports were prepared to analyze the specificity of anti-dextran antibodies. Silica beads were grafted with native dextran or with functionalized dextran. The anti-dextran antibodies present in some human sera were analyzed by enzyme-linked immunosorbent assay method. These antibodies play an important role in severe dextran-induced anaphylactic reactions in humans by forming immune complexes with clinical dextran. The results indicated that two distinct populations of anti-dextran antibodies were purified from human serum, using dextran-coated silica beads. Elution from this support with an oligo-dextran of 4000 g/mol allowed the isolation of one population that only recognized native dextran as antigen. Functionalized dextran coated on dextran silica beads led to the purification, with a glycine-HCl buffer, of another subclass of antibodies that recognized substituted dextran derivatives. Furthermore, these antibodies could be useful tools for in vitro and in vivo investigations using dextran derivatives as bio-active polysaccharides.     

Isolation of high-affinity antibodies from hyperimmune serum

A group of high-affinity antibodies has been isolated from horse hyperimmune antiplague serum with the use of antigenic immunosorbent. High-affinity antibodies have proved to be homogeneous, which is indicated by the rectilinear character of the graph of the inverse values of the free antigen concentration.     

Isolation, purification and characterization of surface antigens of the bovine filarial parasite Setaria digitata for the immunodiagnosis of bancroftian filariasis

The surface antigens of the bovine filarial parasite Setaria digitata were isolated by EDTA extraction and purified by affinity chromatography using sepharose bound human filarial (Wuchereria bancrofti) antibodies obtained from chronic human filarial sera. The purified and crude antigens were used in enzyme-linked immunosorbent assay (ELISA) for the detection of serum antibodies in bancroftian filariasis. The purified antigen showed sensitive and specific reactions in ELISA for the detection of antibodies in filarial sera and showed least cross reactivity with other parasitic infections. The crude and purified antigens showed about 18 and 6 peptide bands respectively in SDS-PAGE and about 11 and 6 antigenic bands respectively in enzyme-linked immunoelectrotransfer blot (EITB). The purified antigen was observed to be glycoprotein in nature. It was possible to identify the stage-specific infection in human filariasis by using the crude and purified antigens in EITB.     

Antigenic determinants of blood serum proteins detected in the structure of hepatitis B surface antigen by the method of affinity chromatography]

Tropism of the antigen of hepatitis B to the antibodies against normal serum proteins was revealed by the method of affine chromatography; this pointed to the possibility of the presence in the HBs-antigen structure of some antigenic determinants of the serum proteins or to the association of serum proteins with the HBs-antigen. A change of the isoelectric spectrum of the HBs-antigen and its tropism in affine chromatography to the antibodies against serum proteins possibly depended both on the nonhomogeneity of the antigenic determinants included into the composition of the antigen, and on the presence of the HBs-antigen--HBs-antibody or HBs-antigen--serum proteins complexes.     

Immunological crossreactivity to the catabolite control protein CcpA from Bacillus megaterium is found in many Gram-positive bacteria

Abstract The catabolite control protein CcpA from Bacillus megaterium was overproduced as a fusion protein to a 6xhis affinity tag and purified to homogeneity. Polyclonal antibodies of high affinity and specificity were raised against the purified protein. The serum did not crossreact with purified Lac repressor despite the fact that CcpA and LacI belong to the same protein family. Using this antiserum we identified proteins that share antigenic determinants with CcpA in many Gram-positive bacteria, including bacilli, staphylococci, streptococci, lactic acid bacteria, and some actinomycetes.     

Antigen-antibody interaction. The immunodominant region of EDP208 pili

The EDP208 pilus contains a major antigenic determinant in the N-terminal dodecapeptide, as shown by E. A. Worobec, A. K. Taneja, R. S. Hodges, and W. Paranchych ((1983) J. Bacteriol. 153, 955-961). This peptide was chemically synthesized, coupled to bovine serum albumin with N-hydroxysuccinimidyl p-azido-benzoate, and used in immunoblot and enzyme-linked immunosorbent assays to show it was capable of reacting with anti-EDP208 pilus antibodies. Antibodies raised against the synthetic peptide conjugate were also capable of reacting with whole pili in these assays. To further examine the specific residues responsible for the antigenicity of this site, several peptide analogs were chemically synthesized. The relative affinity of these peptides for anti-EDP208 pilus antibodies was determined by a competitive enzyme-linked immunosorbent assay using the Fab fragment of anti-EDP208 pilus immunoglobulin G. From these results we established that the antigenic region of this peptide was the N-terminal pentapeptide, N-acetyl-Thr-Asp-Leu-Leu-Ala, and the key residues responsible for the antibody-antigen interaction are the N-acetyl-Thr1, Leu3, and Leu4. Hydrophobic interactions involving the methyl of the acetyl group and the leucine side chains make the largest contributions to the antigen-antibody interaction, while a lesser contribution is made by the Thr1 hydroxyl. The side chains of Asp2 and Ala5 contribute only weakly to the stabilization of the antigen-antibody complex.     

Production and characterization of four monoclonal antibodies against porcine pancreatic colipase

Four monoclonal antibodies directed against porcine colipase have been generated by hybridization of myeloma cells with spleen cells of BALB/c immunized mice. Antibodies were screened by binding to immobilized colipase in a solid-phase assay. Monoclonal antibodies were purified by affinity chromatography on colipase coupled to Sepharose. All monoclonal antibodies are of the IgG1 class with high affinity for the antigen. The dissociation constant of the complex formed in solution between porcine colipase and antibody varied from 1.1 X 10(-10) M to 1.8 X 10(-8) M. Epitope specificity was studied for each antibody and in pairs with an enzyme-linked immunosorbent assay (ELISA). Results indicate that the four monoclonal antibodies react with at least three different antigenic regions of colipase. Finally, three monoclonal antibodies were found to be potent inhibitors of colipase activity. Antiporcine monoclonal antibodies appear to be suitable probes for studying the lipid affinity site of the protein cofactor of pancreatic lipase.     

Mapping antibody binding sites on cytochrome c with synthetic peptides: Are results representative of the antigenic structure of proteins?

Crystallographic work on antigen-antibody complexes has revealed that extensive surface areas of proteins may interact with antibodies. On the other hand, most experimental approaches to locate and define antigenic determinants of protein antigens rely on the linear sequence of the polypeptide chain. Hence the question arises whether mapping of antibody binding sites by analysis of the reactivity of anti-protein antibodies with synthetic peptides can provide a representative picture of the antigenic structure of a protein antigen. We have addressed this question using yeast iso-1 cytochrome c as a protein antigen against which antisera were raised in rabbits. The reaction of the antisera with 103 synthetic hexapeptides covering the entire sequence of cytochrome c was tested by the pepscan procedure in which peptides are coupled to polyethylene rods and tested by ELISA. For the assay, anti-cytochrome c antibodies were fractionated by affinity chromatography on native yeast iso-1 cytochrome c and on apo-cytochrome c; the latter is a random coil. It was found that only antibodies retained by the apo-cytochrome c affinity column react with synthetic peptides. These antibodies comprise a small fraction, probably less than 2%, of all cytochrome c-specific antibodies. The majority of antigenic determinants, which seem to consist of strongly conformation-dependent topographic epitopes, could not be uncovered by the peptide approach. Epitope mapping with short peptides seems of limited usefulness in the case of small, globular, and conformationally stable proteins like cytochrome c.     

Immunogenicity of modified by dextran recombinant fragment of Bac protein of group B streptococci

Opportunity to increase of immunogenicity of recombinant polypeptide P6 constructed on the basis of surface protective Bac protein by its chemical conjugation with dextran (D) 40 was studied. 3 preparations with different quantity of protein and polysaccharide components were obtained. Their testing with standard serum showed that antigenic determinants of the polypeptide were preserved although partly enclosed and structure of antigenic determinants did not significantly changed. On the model of subcutaneous immunization of mice it has been shown that two preparations--P6D2 and P6D3--have improved immunological characteristics. Conjugation of polypeptide P6 with dextran let to increase of immune response to P6 and affinity of P6-specific antibodies. Injection of nonconjugated P6 and dextran mixture showed that free dextran is not immunogenic and it suppress synthesis of P6-specific antibodies without effect on their affinity. Intranasal administration of nonconjugated P6 did not lead to P6-specific IgG in serum. After conjugation with dextran polypeptide P6 was recognized as an antigen and stimulated production of small quantity of antibodies. Technological process of chemical binding of protein antigen with polysaccharides, which let to regulate protein and polysaccharide components ratio, can be the effective method to increase immunogenicity of recombinant polypeptides.     

Antigen-antibody complex dissociation in affinity chromatography

Different methods of the elution of antibodies from an immunosorbent column have been studied, the serological activity and affinity of eluted antibodies have been evaluated in the enzyme immunoassay. The activity of conjugates (peroxidase-labeled antibodies) has been shown to depend not only on the serological activity and affinity of antibodies, but also on the method of binding antibodies with the enzyme.     

Nuclear glutamate dehydrogenase: unique antigenic determinants and determinants common to the mitochondrial enzyme

An antiserum against glutamate dehydrogenase from ox liver nuclei precipitates both the nuclear and the mitochondrial enzymes, with different equivalence zones. The antibodies of this serum have been fractionated by means of an immunoadsorbent to which mitochondrial glutamate dehydrogenase is covalently linked. After the affinity chromatography, the unretained antibodies had virtually lost the ability to precipitate the mitochondrial enzyme, whereas the retained portion, after elution, precipitated both glutamate dehydrogenases. These findings suggest that nuclear glutamate dehydrogenase contains specific antigenic determinants as well as determinants common to the mitochondrial enzyme, and that only the antibodies against the latter determinants have been selectively removed by the affinity chromatography.     

Immunochemical quantification of procion red HE-3B used as ligand in affinity chromatography.

The quantification of Procion Red HE-3B used as a ligand in affinity chromatography for proteins is reported. It's based on an enzyme-linked immunosorbent assay using antibodies against the dye. Polyclonal antibodies were classically prepared after conjugation of the dye on KLH and injection into rabbits. The development of the assay was based on the competitive inhibition between hemoglobin-dye complex and free dye. The sensitivity of this method was about 1000-times higher than a classical spectrophotometric assay, and was modulated by some chemical substituents attached on the native dye. It was demonstrated that the assay was applicable to the determination of dye traces that may be released from dye affinity sorbents. Moreover, the quantification of the dye was successfully applied to proteins that are being purified from a dye affinity column.     

Coexpression of cancer-associated carbohydrate antigens,Tn and sialyl Tn

The expression of cancer-associated antigens, Tn and sialyl Tn, was examined using monoclonal antibodies, MLS 128 and MLS 102, recognizing these two antigens, respectively. A cell lysate from a human carcinoma cell line, LS 180 cells, was analysed by Western blotting using these two antibodies. Three glycoprotein bands were discernible with each antibody, of which two, corresponding to 250 and 210 kDa, were reactive with both the antibodies. LS 180 cells were metabolically labelled with³H-glucosamine and then the lysate from these cells was applied to two immunoaffinity columns. Sixty-five per cent of the Tn antigenic glycoproteins, based on radioactivity, bound to the MLS 102 affinity column. On the other hand, 45% of the sialyl Tn antigenic glycoproteins bound to the MLS 128 affinity column. These results indicate that some Tn and sialyl Tn antigens were expressed on the same polypeptide chains.The presence of non-sialylated GalNAc residues on the polypeptide chain with many Sia-GalNAc residues appears to be due to the incapability of three consecutive moieties of GalNAc-Ser/Thr to accept sialic acid.Abbreviations PSMF phenylmethylsulfonyl fluoride - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - GalNAc N-acetylgalactosamine - Sia sialic acid