EVALUATION OF ENZYME-LINKED IMMUNOSORBENT ASSAYS FOR THE DETECTION OFCYMBIDIUM MOSAIC-VIRUS IN ORCHIDS

Indirect enzyme-linked immunosorbent assay (ELISA) and double antibody sandwich (DAS) ELISA using polyclonal antibodies (PAb), egg yolk immu noglobulin G (IgY), rabbit antisera (IgG) or monoclonal antibodies (MA b) alone, or any two in combination, were compared for the detection o f Cymbidium mosaic virus (CyMV) in orchids. An indirect ELISA using Ig G, IgY or MAb was able to detect 50-100 ng of purified virus and 2-8-f old dilution of infected leaf extract. Detection of purified CyMV by D AS-ELISA using IgY as the detecting antibody gave 4-16 times higher se nsitivity than that using IgG on either MAb or PAb coated microplates. The DAS-ELISA using MAb as the coating antibody and IgY as the detect ing antibody was shown to be the most sensitive, being able to detect 6.25 ng of purified virus and 1024-fold dilution of an infected leaf e xtract.