Production, characterization, and uses of monoclonal antibodies against porcine reproductive and respiratory syndrome virus 3' untranslated region and nucleoprotein RNA binding proteins.

Previous studies in our laboratory of interactions between the 3' untranslated region of porcine reproductive and respiratory syndrome virus (PRRSV) and MARC 145 cell cytoplasmic proteins have identified 11 RNA binding proteins. Here, we report the production and characterization of monoclonal antibodies (MAbs) against a 67-kD RNA binding protein of MARC 145 tissue cultured cells. Of the MAbs produced, 11 were reactive in ELISA with 67-kD protein. Immunoprecipitation tests showed that six clones precipitated a protein of 67 kD, and one clone recognized a multiple protein bands of 45, 37, and 27 kD. Western blotting showed that these clones detected two proteins of 67 and 55 kD. Indirect fluorescent antibody staining of testing of PRRSV-infected cells with these MAbs revealed diffuse cytoplasmic staining and intense perinuclear staining to one side of the nucleus. The presence of the double membrane vesicles in the same region in PRRSV-infected alveolar macrophages suggests that these RNA binding proteins might have a role in their formation.