Major Immunogenic Protein Research Articles

Heterogeneity of Trichomonas vaginalis and discrimination among trichomonal isolates and subpopulations with sera of patients and experimentally infected mice

The antibody response in trichomoniasis patients was examined with a variety of methodologies including enzyme-linked immunosorbent assays, indirect immunofluorescence, immunoblotting, and radioimmunoprecipitation-electrophoresis-autoradiography. Based on enzyme-linked immunosorbent assay recognition of trichomonal isolates, sera from patients with trichomoniasis were categorized into reactive class I (IA, IB, and IC) and nonreactive class II sera. A diminished ability to precipitate antibody-binding trichomonad membrane proteins by the whole cell radioimmunoprecipitation assay was noted from class IA to class II sera. The antigenic distinctions among various Trichomonas vaginalis isolates appeared due to high-molecular-weight protein antigens detected by class IA sera in a whole cell radioimmunoprecipitation assay. The heterogeneity in antigenic patterns was confirmed among the isolates with sera from experimental animals. Also, live T. vaginalis cells appear to have only a few of the entire repertoire of major immunogenic surface proteins accessible to antibody binding. Immunoblotting demonstrated that the high-molecular-weight proteins responsible for trichomonal isolate heterogeneity are present in all isolates. The data suggest that trichomonads of a given isolate express only a subset of internally synthesized protein antigens on their surface. Importantly, the presence of these protein antigens on T. vaginalis membranes correlated with antibody production in subcutaneously challenged mice. Finally, indirect immunofluorescence studies with highly reactive, pooled sera from either patients or mice revealed a subpopulation of nonstaining trichomonads. These data support the view that heterogeneity among T. vaginalis is dependent upon the surface disposition of highly immunogenic protein antigens. Strategies may now be developed not only for studying potential vaccine reagents, but also for examining possible antigenic phenotypic variations in this experimental model.

Monoclonal antibody-mediated immunoprecipitation of proteins from cell, infected with marek's disease virus or turkey herpesvirus

The major immunogenic viral proteins of Marek's disease virus (MDV) and turkey herpesvirus (HVT) share antigenic determinants. The polyacrylamide gel electrophoresis pattern of five viral polypeptides immunoprecipitated with homologous convalescent chicken plasma was identical with the pattern obtained after immunoprecipitation with heterologous convalescent chicken plasma. A panel of monoclonal antibodies was used to identify MDV and HVT polypeptides. Sixteen monoclonal antibodies were positive in an immunofiuorescence assay. However, only eight monoclonal antibodies immunoprecipitated a total of seven distinct viral proteins from MDV- and HVT-infected cells. Six of these monoclonals immunoprecipitated multiple viral proteins. None of the monoclonal antibodies recognized the common A antigen of MDV or HVT. Monoclonal antibodies immunoprecipitated three glycoproteins (100,000, 60,000, and 49,000 Da) that comigrate in polyacrylamide gels with three of the five common polypeptides obtained with the convalescent chicken plasma. In addition, a 79,000-Da protein was common to all MDV- and HVT-infected cells. Competition immunoprecipitation and peptide mapping by limited proteolysis confirmed that the three glycoproteins and the 79,000-Da protein contain MDV-HVT common epitopes. MDV-specific antigenic determinants were detected on the three remaining viral proteins (41,000, 38,000, and 24,000 Da).

Structure of the FMDV translation initiation site and of the structural proteins.

A cDNA clone of Foot and Mouth Diseases Virus (FMDV), strain C1, has been sequenced. The limits of the structural genes were defined by comparison with the available protein data. We identified two potential translation initiation sites for the viral polyprotein separated by 84 nucleotides. We suggest that these two initiation sites could be used to express two proteins differing only at the N-terminal, P16 and P20a. This model is supported by the fact that antiserum against a bacterially synthesized polypeptide corresponding to the anterior region of the polyprotein precipitates specifically both P16 and P20a. Comparison of the C1 sequence with two other serotypes, O1K and A10 revealed variability in the major immunogenic structural protein, VP1, and also in two other capsid proteins, VP2 and VP3. P16/P20a, VP4, and the N-terminal part of the precursor of the nonstructural genes, P52, are rather conserved between the different FMDV strains.

Sj23, the target antigen in Schistosoma japonicum adult worms of an immunodiagnostic hybridoma antibody.

An IgG2a mouse hybridoma-derived antibody (designated I.134) has been identified which binds to Schistosoma japonicum adult worms and which has immunodiagnostic potential (for detection of antibody) in schistosomiasis japonica in the Philippines. The target epitope of this hybridoma antibody is contained in a 23 000 molecular weight protein of adult worms as analysed by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis of immunoprecipitates and a gel overlay technique. This adult worm antigen has been labelled biosynthetically using 35S-methionine as well as exogenously using lactoperoxidase-catalysed radioiodination and the Bolton and Hunter reagent with intact worms. As anticipated, the low molecular weight protein antigen (designated Sj23) appears to be one of several major immunogenic proteins of worms which induce antibodies in infected Philippine patients.