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ABSTRACT. Objective. Rheumatoid arthritis (RA) is a chronic inflammatory polyarthritis; while the cause is unknown, it has been speculated that an infectious agent could be the trigger for the disease. Numerous attempts at isolating an agent have been unsuccessful. Our purpose was to identify a virus from diseased tissue from a patient with RA. Methods. Diseased tissue taken at the time of knee replacement surgery from a patient with RA was inoculated into several cell lines and observed for cytopathic effect. Cells from the tissue were also grown as explants and were examined for viruses. Synovial fluid drawn 4 years prior to the surgery and frozen at -70°C was also inoculated into cell lines. Following the development of a cytopathic effect and identification of the agent, sera from 50 patients with rheumatoid factor (RF)-negative RA were examined for IgM antibodies to the agent. Results. After many inoculations and numerous subpassages, measles virus was identified in 6 cell lines inoculated with either the minced tissue or synovial fluid. Six cell lines co-cultivated with one or more of 9 explants also showed the presence of measles virus. Measles virus was confirmed by immunofluorescence and by neutralization. Eleven of 50 (22%) sera samples from patients with RF-negative RA had IgM antibodies to measles virus recombinant nucleoprotein. Conclusion. There is an association between measles virus an

Isolation of Monoclonal Antibodies with Predetermined Conformational Epitope Specificity

Existing technologies allow isolating antigen-specific monoclonal antibodies (mAbs) from B cells. We devised a direct approach to isolate mAbs with predetermined conformational epitope specificity, using epitope mimetics (mimotopes) that reflect the three-dimensional structure of given antigen subdomains. We performed differential biopanning using bacteriophages encoding random peptide libraries and polyclonal antibodies (Abs) that had been affinity-purified with either native or denatured antigen. This strategy yielded conformational mimotopes. We then generated mimotope-fluorescent protein fusions, which were used as baits to isolate single memory B cells from rhesus monkeys (RMs). To amplify RM immunoglobulin variable regions, we developed RM-specific PCR primers and generated chimeric simian-human mAbs with predicted epitope specificity. We established proof-of-concept of our strategy by isolating mAbs targeting the conformational V3 loop crown of HIV Env; the new mAbs cross-neutralized viruses of different clades. The novel technology allows isolating mAbs from RMs or other hosts given experimental immunogens or infectious agents