The common antigenic determinants of the H antigens of salmonellae]

Salmonella H-antigens have common and specific antigenic determinants. Studies on the determination of common antigenic determinants of H-antigens (a; b; d; i; 1,2 and nt) has been carried out. The order of the distribution of H-antigens according to the decrease of these common antigenic determinants in size is presented: d greater than a greater than 1,2 greater than b greater than nt. These data broaden our knowledge of the structure of H-antigens; they are also necessary for obtaining specific antibodies and conjugate preparations used in the enzyme immunoassay.     

Antigenic characterization of flavivirus structural proteins separated by isoelectric focusing.

Isoelectrofocusing of nonionic-detergent-disrupted flaviviruses separated the envelope glycoprotein of 53,000 to 58,000 daltons and the nucleocapsid protein of 14,000 daltons. The envelope protein and nucleocapsid protein were isolated at isoelectric points of pI 7.8 and 10.3, respectively. The antigenic determinants of St. Louis encephalitis, Japanese encephalitis, and dengue virus envelope and nucleocapsid proteins were examined by solid-phase competition radioimmunoassay. By the appropriate selection of antiserum and competing proteins, it was possible to distinguish type-specific, complex-reactive and flavivirus group-reactive antigenic determinants. The envelope glycoproteins of St. Louis encephalitis, Japanese encephalitis, and dengue viruses were found to contain each of these three classes of antigenic determinants. Most of the determinants on the envelope protein were type specific, some were complex reactive, and a small fraction were flavivirus group reactive. The nucleocapsid protein contained only flavivirus group-reactive antigenic determinants.     

Expression of an onco-developmental antegen among avian species.

Rabbit antisera directed against an onco-developmental antigen on chicken red blood cells have been serologically dissected through specific adsorptions. It is now possible to detect 13 antigenic determinants with the fractionated antisera. The onco-developmental antigen referred to as chicken fetal-leukemic antigen (CFA) is fetal-specific in the white Leghorn chicken, being present on the embryonic but not adult peripheral red blood cells of non-being present on the embryonic but not adult peripheral red blood cells of non-leukemic birds. However, one or more of the onco-developmental antigenic determinants have been detected on adult peripheral red blood cells of non-Gallus avian species, as well as on red blood cells from two adult chicken varieties. For phylogenetic purposes, red blood cells from avian species were characterized for their combinations of CFA determinants. Comparisons among species revealed specific patterns of antigenic expression within phylogenetic groups. Several CFA determinants were restricted in their occurrence to species within a single family, and one determinant was found in all cases where CFA was expressed. The distribution of CFA determinants was used to determine immunological distances among four Galliform species. These distances agreed with the immunological relationships established using different serological markers.     

The ABO, Lewis and related blood group antigens; a review of structure and biosynthesis

Numerous studies have shown that the antigenic determinants of the ABO blood group system are closely related in biochemical terms to the antigenic determinants of the Hh, P, Lewis and Ii blood group systems. The blood group antigens of each of these systems are formed by the addition of specific sugars to an oligosaccharide precursor chain which may be bound through sphingosine to fatty acids (glycolipid) or through serine or threonine to a peptide chain (glycoproteins). The direct gene products of each of these blood group systems are the glycosyltransferase enzymes which catalyse the addition of the specific sugar thus conferring the specified blood group activity to the glycolipid or glycoprotein molecule. The antigenic determinants of the ABO and Lewis systems in addition to red cells also exist in the body secretions in soluble form when the relevant genes are expressed in the phenotype. The antigens expressed on both the red cells and in the secretions are determined by the interaction of Hh, Sese, ABO and Lele genes.     

The ABO, Lewis and related blood group antigens; a review of structure and biosynthesis

Abstract Numerous studies have shown that the antigenic determinants of the ABO blood group system are closely related in biochemical terms to the antigenic determinants of the Hh, P, Lewis and Ii blood group systems. The blood group antigens of each of these systems are formed by the addition of specific sugars to an oligosaccharide precursor chain which may be bound through sphingosine to fatty acids (glycolipid) or through serine or threonine to a peptide chain (glycoproteins). The direct gene products of each of these blood group systems are the glycosyltransferase enzymes which catalyse the addition of the specific sugar thus conferring the specified blood group activity to the glycolipid or glycoprotein molecule. The antigenic determinants of the ABO and Lewis systems in addition to red cells also exist in the body secretions in soluble form when the relevant genes are expressed in the phenotype. The antigens expressed on both the red cells and in the secretions are determined by the interaction of Hh, Sese, ABO and Lele genes.     

Localization of sequential antigenic determinants on bovine beta-casein with synthetic peptides and antisera from mouse, rabbit, and goat.

The antigenic determinants of bovine beta-casein (beta-CN) were localized by using twenty overlapping peptides encompassing the entire sequence of beta-CN and anti-beta-CN antisera from outbred mouse, rabbit and goat. The profile of the reactions was characteristic to the species, the dominant antigenic regions being 80-95, 143-158 and 195-209 in mouse, 1-16 in rabbit and 100-115 in goat. Regions 1-16, 100-115, 121-136 and 143-158 were antigenic in all three species. The number of antigenic regions recognized by goat was much fewer than that by mouse and rabbit, possibly because of the homology between bovine and goat beta-CN. A mixture of the twenty peptides could absorb about 50-60% of beta-CN specific antibodies from each species. Furthermore, the mouse and rabbit anti-beta-CN antibodies were also specific to the phosphorylated regions. We therefore conclude that the major antigenic determinants on beta-CN would be largely sequential and include the phosphorylated sites.     

Primate retroviruses: envelope glycoproteins of endogenous type C and type D viruses possess common interspecies antigenic determinants.

The major 70,000- to 80,000-molecular-weight envelope glycoproteins of the squirrel monkey retrovirus, Mason-Pfizer monkey virus, and M7 baboon virus and the related endogenous feline virus, RD114, were isolated and immunologically characterized. Immunoprecipitation and competition immunoassay analysis revealed these viral envelope glycoproteins to possess several distinct classes of immunological determinants. These include species-specific determinants, group-specific antigenic determinants unique to endogenous primate type C viruses, and group-specific determinants for type D viruses such as Mason-Pfizer monkey virus and squirrel monkey retrovirus. In addition, a class of broadly reactive antigenic determinants shared by envelope glycoproteins of both type C viruses of the baboon/RD114 group and type D viruses of the Mason-Pfizer monkey virus/squirrel monkey virus group are described. Other mammalian oncornaviruses tested, including isolates of nonprimate origin and representative type B viruses, lacked these determinants. The demonstration of antigenic determinants specific to envelope glycoproteins of type C and type D primate viruses indicates either that these viruses are evolutionarily related or that genetic recombination occurred between their progenitors. Alternatively, endogenous type D oncornaviruses may be replication defective, and acquisition of endogenous type C viral genetic sequences coding for envelope glycoprotein determinants may be necessary for their isolation as infectious virus.     

Cloning and characterization of the Leishmania (Viannia) braziliensis Hsp70 gene. Diagnostic use of the C-terminal fragment rLb70(513-663)

Cross-reactions between Leishmania braziliensis and Trypanosoma cruzi caused by common antigenic determinants hinder the specific diagnosis of cutaneous and mucocutaneous leishmaniasis (CL and MCL). Therefore, the usefulness of the 70-kDa heat shock protein (Hsp70) from L. braziliensis for differential serodiagnosis was investigated. The single-copy gene encoding Hsp70, consisting of 663 amino acids, was isolated from a genomic DNA library. The antigenicity data show that Hsp70 is an immunodominant antigen highly recognized (84%) by sera of patients with CL and MCL and to a lesser extent by chagasic patients (18.75%). Antigenic mapping of the 5 overlapping fragments into which the protein was split showed that the main antigenic determinants are located in the carboxy-terminal end. The linear antigenic determinants that show cross-reactions with chagasic sera are located in the fragment rLb70(352-518). The carboxy-terminal fragment rLb70(513-663) presents 70% sensitivity and 100% specificity, so it could be a potential candidate for specific serodiagnosis of CL and MCL caused by L. braziliensis.     

M467: a murine IgA myeloma protein that binds a bacterial protein. I. Recognition of common antigenic determinants on Salmonella flagellins.

We have studied the binding of M467, an IgA murine myeloma protein, to flagellin from seven species of Salmonella. It was found that M467 was reacting with antigenic determinants that were common to all the flagellins studied. These determinants were not related to serotypic antigens. Electronmicrographs of unreduced M467 showed a variety of polymeric species bound to flagella in a manner that could produce immobilization as well as agglutination and precipitation through cross-linking of antigenic determinants. Immunodiffusion in agar gel revealed that M467 was recognizing more than one group of peptide determinants on the flagellins studied. Passive hemagglutination inhibition and a solid phase radioimmunoassay provided evidence that there were differences in binding avidities between M467 and the various Salmonella flagellins studied. It was concluded that M467 is binding more than one specific group of antigenic peptide determinants on flagellin molecules. Flagellin from four of the seven species of Salmonella studied were deficient in one or more of these determinants.     

The Antigenicity of Lipoxygenase from Various Plant Sources

Lipoxygenase enzymes isolated from soya bean, potato and egg-plantare antigenic, and precipitate with their specific antibodies.All three enzymes have common determinants, since there is cross-reactionamong them. Each of the enzymes is strongly inhibited by antibodiesof soya bean and potato lipoxy-genase. Some of the determinantsare heat stable (to 100 °C) and can compete after heat treatmentwith the same determinants of the natural enzyme for the sameantibody. The peptides which carry the determinant to whichthe antibody is bound, causing inhibition of enzymatic activityof soya bean and egg-plant lipoxygenase, have been isolated. It is likely that the active site is not identical with anyof the antigenic determinants, but it is certainly close toone or several of them. Thus the specific antibody causes sterichindrance of the active site.     

Location of attachment moiety on Mycoplasma pneumoniae

Mycoplasma pneumoniae initiates infection in the human host by attachment to respiratory epithelium. The organism attaches by a specialized terminal structure. Monoclonal antibodies to an organism surface protein (P1) inhibited attachment to respiratory epithelium and were localized to the tip structure by a ferritin antibody label. The P1 protein was degraded by trypsin treatment to smaller polypeptides that possessed the same antigenic determinants as the larger P1 protein when reacted with the specific monoclonal antibody, and evidence has been provided for the existence of multiple antigenic determinants on the attachment protein.     

Detection of structural differences between nuclear and mitochondrial glutamate dehydrogenases by the use of immunoadsorbents.

Structural differences between crystalline mitochondrial and nuclear glutamate dehydrogenases from ox liver have been detected by immunological techniques. Antisera prepared against each enzyme precipitate both glutamate dehydrogenases; upon immunodiffusion, the antiserum against the nuclear enzyme gives a line of incomplete identity with the two antigens, whereas the antiserum against the mitochondrial enzyme gives a line of complete identity. Fractionation of the antibodies contained in each antiserum by means of an immunoadsorbent, to which the nuclear or the mitochondrial enzyme has been covalently linked, shows that nuclear glutamate dehydrogenase (GDH) contains specific antigenic determinants as well as determinants common to the mitochondrial enzyme, whereas the latter appears to have no antigenic portions which are not present in the nuclear antigen, in accord with the results of immunodiffusion. The antibodies against determinants common to both enzymes precipitate and inhibit them, whereas the specific anti-nuclear GDH antibodies precipitate but do not inhibit the nuclear antigen.     

The structure of an antigenic determinant in a protein

The immunogenic and antigenic determinants of a synthetic peptide and the corresponding antigenic determinants in the parent protein have been elucidated. Four determinants have been defined by reactivity of a large panel of antipeptide monoclonal antibodies with short, overlapping peptides (7-28 amino acids), the immunizing peptide (36 amino acids), and the intact parent protein (the influenza virus hemagglutinin, HA). The majority of the antipeptide antibodies that also react strongly with the intact protein recognize one specific nine amino acid sequence. This immunodominant peptide determinant is located in the subunit interface in the HA trimeric structure. The relative inaccessibility of this site implies that antibody binding to the protein is to a more unfolded HA conformation. This antigenic determinant differs from those previously described for the hemagglutinin and clearly demonstrates the ability of synthetic peptides to generate antibodies that interact with regions of the protein not immunogenic or generally accessible when the protein is the immunogen.     

Recombination among Protein II genes of Neisseria gonorrhoeae generates new coding sequences and increases structural variability in the Protein II family

Expression of Neisseria gonorrhoeae Protein II (P.II) is subject to phase variation and antigenic variation. The P.II proteins made by one strain possess both unique and conserved antigenic determinants. To study the mechanism of antigenic variation, we cloned several P.II genes, using as probes a panel of monoclonal antibodies (MAbs) specific for unique determinants. The DNA sequences of three P.II genes showed that they shared a conserved framework, with two short hypervariable (HV) regions being responsible for most of the differences among them. We demonstrated that unique epitopes recognized by the MAbs were at least partially encoded by one of the HV regions. Moreover, we found that reassortment of the two HV regions among P.II genes occurs, generating increased structural and antigenic variability in the P.II protein family.     

Synthesis,characterization and immunochemical evaluation of cephalosporin antigenic determinants

Lack of knowledge of the exact chemical structure of cephalosporin antigenic determinants has hindered clinical interpretation of adverse reactions to these drugs and delayed understanding of the mechanisms involved in the specific recognition and binding of IgE molecules to these antigenic determinants. We further resolve the relationship between structure and activity of proposed antigenic chemicals, including the rational design and synthesis of these haptenic structures. Comparative RAST inhibition studies of the synthesized molecules revealed that they were recognized by IgE antibodies induced by cephalosporin antibiotics. Thus, these data indicate that recognition is mainly directed to the acyl side chain and to the beta-lactam fragment that remains linked to the carrier protein in the cephalosporin conjugation course.     

Immunochemical characteristics of the subunits of cholera enterotoxin and of thermolabile Escherichia coli enterotoxins of various origins

Antigenic determinants of subunits A and B of cholera enterotoxin (CT), heat-labile enterotoxin from the human E. coli strain (hLT) and heat-labile enterotoxin from the porcine E. coli strain (pLT) were analysed by Ouchterlony double gel-diffusion test against antisera to B subunits of three toxins and antisera to three holotoxins. The results have shown the existence of the following antigenic determinants: in subunits B-1. antigenic determinants, common for B subunits of all three enterotoxins-B(chp); 2. group antigenic determinants, common for B subunits of two toxins in the pair-B(ch), B(hp); 3. antigenic determinants, unique for B subunits of each CT, hLT, pLT-(B(c), B(h), B(p); in subunits A.-1. antigenic determinants, common for A subunits of all three enterotoxins-A.(chp); 2. group antigenic determinants, common for A subunits of two enterotoxins (hLT and pLT/-A(hp); 3. antigenic determinants, unique for A subunit of CT-A(c). On the basis of these results antigenic formulas for subunits of CT, hLT, pLT were proposed.     

Cell Recognition: Antigenic Determinants of Plant Organs and Their Cultured Callus Cells

We present evidence that plant cells, like animal cells, may be typed according to their specific cellular determinants. Stems, leaves, pistils, and anthers of sweet cherry, Prunus avium , and their derived callus cells in culture have been examined by immunological methods to determine both to what extent parental characteristics are retained by the callus cells and the relationship between callifrom different organs. For the organs, some antigenic determinants were shared while others were unique to a particular organ. Callus cells derived from different organs share some common determinants, while others are specific. Although the callus cells from a particular organ retained their antigenic individuality, they also expressed a wider range of determinants than their parental tissues. Parental antigens were still expressed in callus cells after four subcultures. In suspension culturès of leaf and pistil callus, the organ-specific antigens were present in the culture filtrate and were associated with the protein rather than polysaccharide fractions.     

Phage antibodies for the immunochemical characterization of Herbaspirillum seropedicae Z78 glycopolymers

Microbial carbohydrate antigens are targets of the immune systems of hosts. In this context, it is of interest to obtain data that will permit judgment of the degree of heterogeneity, chemical makeup, and localization of the antigenic determinants of the Herbaspirillum surface glycopolymers. A sheep single-chain antibody-fragment phage library (Griffin.1, UK) was used to obtain miniantibodies to the exopolysaccharides (EPS-I and EPS-II), capsular polysaccharides (CPS-I and CPS-II) and lipopolysaccharide (LPS) of Herbaspirillum seropedicae Z78. To infer about the presence or absence of common antigenic determinants in the cell-surface polysaccharides of H. seropedicae Z78, we ran a comparative immunoassay using rabbit polyclonal and phage recombinant antibodies to the surface glycopolymers of H. seropedicae Z78. We isolated and purified the exopolysaccharides (EPS-I and EPS-II), capsular polysaccharides (CPS-I and CPS-II), and lipopolysaccharide (LPS) of Herbaspirillum seropedicae Z78. Using rabbit polyclonal antibodies, we found that these cell-surface polysaccharides were of a complex nature. EPS-I, EPS-II, CPS-I, CPS-II, and LPS contained common antigenic determinants. CPS-I, CPS-II, and LPS also contained individual antigenic determinants composed of rhamnose, N-acetyl-d-glucosamine, and N-acetyl-d-galactosamine—sugars responsible for cross-reactions with miniantibodies. The anti-LPS miniantibodies were more specific for the core region of the LPS, in which rhamnose was the most abundant sugar, than they were specific for its O portion. The miniantibodies we isolated can be useful reagents not only in basic biochemical research but also in clinical diagnostic and therapeutic applications.     

Actinobacillus Pleuropneumoniae Serotype 5, Subtypes a and b: Cross Protection Experiments

Vaccination of pigs with a killed culture of A. pleuropneumoniae serotype 5, strain K17 (subtype a) afforded a high degree of protection against challenge with strains L20 and T928 (subtype b). The reverse experiment showed that strain L20 gave good protection against challenge with strain K17 whereas strain T928 did not afford an acceptable protection against challenge with this strain. The considerable cross immunity shown to exist between strains K17 and L20 indicates a high degree of homogeneity of the antigenic determinants of the two strains involved in induction of protective immunity and suggest that antibodies to capsular subtype specific determinants may not play a significant role in the specific defence against A. pleuropneumoniae strains belonging to serotype 5. The finding that a vaccine prepared from strain T928 did not afford an acceptable protection against challenge with strain K17 indicates a variable expression among serotype 5 strains of the antigenic determinants which induce protective immunity against A. pleuropneumoniae infection.