CHARACTERIZATION OF MONOCLONAL-ANTIBODIES TO CONIDIAL ANTIGENS OF PYRICULARIA-GRISEA

Xia, J. Q., Lee, F. N., Kim, K. S., and Spiegel, F. W. 1993. Characterization of monoclonal antibodies to conidial antigens of Pyricularia grisea. Experimental Mycology 17, 170-181. Several monoclonal antibodies (MAbs) prepared against crushed conidia of Pyricularia grisea Sacc. Race IB-49 were characterized by using various immunological analyses. The epitope recognized by MAb 4G11 was present in conidia at high density, in hyphae at low density, and absent in liquid culture medium. MAb 11C6 reacted strongly with hyphae and weakly with conidial antigens. In Western blot analysis, MAb 4G11 bound two major proteins, a 63-kDa protein in crushed conidial suspensions and a 20-kDa protein in saline mycelial washings. Both proteins were present in sonicated mycelial suspensions. The MAb 4G11 also recognized several minor proteins from saline conidial washings with Mr ranging between 23 and 31 kDa. Immunoelectron microscopy demonstrated binding of MAb 4G11 to the cytoplasm of conidial cells and the walls of hyphae. It is hypothesized that the 63-kDa protein was synthesized in the fungal cytoplasm and then excreted as a smaller polypeptide. The epitopes recognized by MAbs 8H1 and 3E4 were located mainly in conidial cytoplasm and expressed on the surfaces of growing points of germ tubes, whereas the epitope to MAb 11C6 was present in both the cell wall and the cytoplasm of hyphae and conidia. © 1993 Academic Press. All rights reserved.