Preparation and characterization of polyclonal antibody against resting spores of Olpidium virulentus , fungal vector of lettuce big-vein disease

Research on Olpidium virulentus , the vector of the serious lettuce big-vein disease, is difficult because its resting spores persist in soil and retain virus for years and the fungus is not culturable. We developed protocols to obtain purified, viable resting spores from infected roots using an enzymatic treatment and two-step density gradient centrifugation and to generate a polyclonal antibody against these spores. The antibody was species-specific in a direct immunostaining assay and in western blots produced two specific bands (ca. 30.5, 29.0 kDa) against resting spores. The detection limit for resting spores in an indirect ELISA was 200 spores/100 μL.