Production of monoclonal antibodies to African cassava mosaic virus and differences in their reactivities with other whitefly-transmitted geminiviruses

Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, U.K. A panel of murine monoclonal antibodies (MAbs), selected by indirect ELISA, was prepared to an isolate (ACMV-JI) of the type strain of African cassava mosaic virus. Of the ten MAbs purified from ascitic fluids, four out of the five tested gave stronger reactions with ACMV-JI in double antibody sandwich ELISA (DAS-ELISA) than did rabbit polyclonal antibody. Six of the ten MAbs gave a precipitin reaction in immunodiffusion tests and nine trapped ACMV-JI particles in immunosorbent electron microscopy. Rabbit polyclonal antibody to ACMV reacted in DAS-ELISA not only with ACMV-JI and the Kenya coast strain of ACMV (ACMV-C) but also with five other geminiviruses known or suspected to have the whitefly Bemisia tabaci as a vector, though not with three geminiviruses that have leafhopper or unknown vectors. Of the ten MAbs studied in detail, four did not react with ACMV-C in indirect ELISA and only two reacted strongly. This supports other evidence that ACMV-C is a distinctive strain of ACMV and not merely a minor variant. The other whitefly-transmitted geminiviruses (bean golden mosaic, euphorbia mosaic, mung bean yellow mosaic and tomato golden mosaic viruses) and Australian tomato leaf curl virus reacted with two to five MAbs but each virus had a different pattern of reactivity. In contrast, solanum apical leaf curling virus, and the leafhopper-transmitted beet curly top and maize streak viruses, did not react with any of the MAbs. The results of competitive binding tests, when combined with the patterns of reaction of individual MAbs with different viruses, indicated that the MAbs were specific for nine distinct epitopes. Two MAbs reacted with all five whitefly-transmitted viruses, suggesting that the epitopes detected by these MAbs may be important for transmission by B. tabaci . Individual MAbs seem suitable for detecting and identifying ACMV, for distinguishing between ACMV-JI and ACMV-C, and for quantitative assays of other whitefly-transmitted geminiviruses. Keywords: ACMV, monoclonal antibodies, geminiviruses Present address: Queensland Department of Primary Industries, Meiers Road, Indooroopilly, Queensland 4068, Australia. Received 25 July 1986; accepted 3 September 1986.