Characteristics of Monoclonal Antibodies to Lucerne Transient Streak Sobemovirus and Their Use in Epitope Localization

Murine monoclonal antibodies (mAbs) to lucerne transient streak sobemovirus (LTSV) were used as probes for examining the virion capsid organization. A panel of nine mAbs from approximately 100 hybridomas were chosen for this study. All of these mAbs interacted effectively with sites on intact capsid and isolated coat protein subunits (i.e. metatopes) in ELISA and Western blots. Only one of these mAbs reacted with virions in gel diffusion test producing a visible precipitin band. Competitive binding assays showed that these mAbs recognized the same or very similar metatopes. None of the mAbs neutralized LTSV virion infectivity but rabbit polyclonal antibodies drastically reduced infectivity. Treatment of virions with EDTA (swollen LTSV). protein crosslinking reagents or sodium dodecyl sulphate caused no detectable alterations in their reactivities with these mAbs, The binding sites for monoclonal and polyctonal antibodies were located on denatured 5.5 kDa fragments resulting from partial trypsinization of LTSV coat protein and 8 kDa fragments formed with chymopapain proteolysis. These results indicate that these LTSV epitopes are of linear (or sequential) configuration and are located on the exposed, structurally stable domain of the virion capsid.