Abstract
Potato leafroll virus (PLRV) antigen was easily detected by enzyme-linked immunosorbent assay (ELISA) in potato foliage which had been collected in commercial fields or grown in a greenhouse. ELISA values were highest in newly expanded leaves and gradually declined with growth. When infected tubers were planted, viral antigen generally could be detected by ELISA before the development of symptoms on potato foliage. The pattern of results of ELISA tests using field-grown potato plants closely corresponded to the pattern of symptom development on potato plants. Since we were able to eliminate the non-specific background of the extracts from healthy green sprouts and tubers by heating for 10min at 50C, ELISA can be employed for PLRV-indexing using green sprouts or tubers. The ELISA values for leaf material desiccated over silica gel remained relatively constant throughout one month of storage and PLRV antigen was readily detected in dried samples. In comparative studies by ELISA and immunosorbent electron microscopy (ISEM), no obvious differences in ability to detect the PLRV antigen were observed. PLRV antigen (in purified preparations) could be accurately detected at even nanogram levels by both immunolological methods.
