Use of Direct Antigen Coating and Protein A Coating ELISA Procedures for Detection of Three Peanut Viruses.

Direct antigen coating (DAC) and protein A coating (PAC) forms of indirect enzyme-linked immunosorbent assay (ELISA) were standardized and compared with the double-antibody sandwich (DAS) form of direct ELISA for their usefulness in the detection of three peanut viruses: peanut mottle virus (PMV), tomato spotted wilt virus (TSWV), and Indian peanut clump virus (IPCV). PMV was detectable in peanut seeds and pea tissue at a 1:10,000 dilution in buffer with the DAC and at a 1:1,000 dilution with the PAC procedures. With the DAS procedure, PMV was detectable in pea tissue at a 1:1,000 dilution and in peanut seed at a 1:100 dilution. TSWV was detectable in peanut leaves at a 1:1,000 dilution with the DAC method and at 1:100 with the PAC and DAS methods. IPCV was detectable in peanut leaves at a 1:100 dilution by the DAC, PAC, and DAS methods. Sensitivity of DAC and PAC methods was, therefore, comparable to that of the DAS procedure under the short incubation period (1–2 hr at 35 C) conditions employed in the experiments.