Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 119260
Immuno-capillary zone electrophoresis (I-CZE) is a technique that combines the specificity afforded by serological assays with the sensitivity, rapidity, and automation in detection provided by capillary zone electrophoresis. Cymbidium mosaic potexvirus (CymMV) and odontoglossum ringspot tobamovirus (ORSV) were detected in their purified forms as well as in the crude saps of infected Nicotiana benthamiana leaves and Oncidium orchid flowers. The two orchid virus-antibody complexes were resolved via the combined actions of electrophoretic migration and electro-osmotic flow along a buffer-filled, uncoated fused-silica capillary. The I-CZE fractions collected from both CymMV- and ORSV-antibody complex peaks, as well as the RNA purified from them, retained their infectivity upon inoculation onto Chenopodium quinoa. I-CZE assays were able to detect as little as 10 fg each of both CymMV and ORSV in their purified forms as well as in the crude saps of infected N. benthamiana and Oncidium orchid. As multiple samples can be analyzed rapidly, I-CZE offers an ideal diagnostic technique for routine mass-indexing programs such as virus-free certification, breeding for virus-resistant cultivars, plant quarantine, and germ plasm screening. This is the first report of the application of I-CZE for the detection of plant viruses.