Both ELISA and Visual Examination METHOD NARR: Wild Solanum species were inoculated by carborundum-spatula technique with diluted sap from Nicotiana previously infected with PVX and PVY. Visual inspections every 7 days and ELISA at the end of 3rd and 6th weeks. In latent host-virus relations back-inoculation to indicator plants was carried out. Visual observations include specific sets of symptoms. Specific ELISA scores not noted. AUTHOR EXPLANATION: Addresses local vs. systemic susceptibility and hypersensitive response.