Antigenic characterization of potato virus X with monoclonal antibodies

1 Laboratory of Immunodiagnostics, Järva-Jaani Collective Farm, 202823 Paide Rajoon, Estonian S.S.R. 2 Department of Molecular Genetics, Institute of Chemical Physics and Biophysics, Academy of Sciences of the Estonian S.S.R., 200026 Tallinn, Akadeemia 23, Estonian S.S.R. 3 Estonian Biocenter, 202400 Tartu, Kingissepa 14/16, Estonian S.S.R. and 4 Institute of Organic Chemistry, Department of Bioorganic Chemistry, Academy of Sciences of the Ukrainian S.S.R., Kiev 94, Ukrainian S.S.R., U.S.S.R. A panel of mouse monoclonal antibodies (MAbs) against potato virus X (PVX) was obtained and three of these which had high affinity to the antigen were characterized in detail. These three antibodies defined two epitopes on PVX and recognized native virus, viral coat protein and denatured viral coat protein in various immunological assays. Two of the MAbs and rabbit anti-PVX polyclonal antibodies bound to the 68 amino acid N-terminal peptide of the PVX coat protein. This implies that the N terminus of the PVX coat protein is exposed at the virus surface and forms a highly immunogenic antigenic determinant. In double antibody sandwich (DAS) ELISA, MAbs and their horseradish peroxidase conjugates reacted with PVX at 10 to 20 ng/ml. Monoclonal antibodies to PVX reacted with virus in potato leaves and tubers and detected the virus in DAS ELISA in various combinations, including in combination with polyclonal antibodies. Keywords: PVX, antigenic determinants, MAbs Received 21 April 1988; accepted 28 April 1988.