Immunoprecipitation of a 50-kDa protein: a candidate receptor component for tomato spotted wilt tospovirus (Bunyaviridae) in its main vector, Frankliniella occidentalis

A 50-kDa protein that binds to viral particles in solid-phase assays and th at is recognized by anti-idiotypic antibodies made against anti-viral glyco proteins G1/G2 (anti-Ids) has been proposed as a receptor candidate for tom ato spotted wilt tospovirus (TSWV) in its main thrips vector, Frankliniella occidentalis Pergande (Bandla et al., 1998. Phytopathology 88, 98-104). He re we show the immunoprecipitation of the 50-kDa protein by anti-Ids and by an anti-G1/G2-TSWV conjugate - a new immunoprecipitation method. In additi on, we show that anti-Ids made against anti-G1 (anti-IdG1) block virus repl ication in an insect tissue replication assay. The results indicate that (a ) the TSWV-50-kDa protein interaction occurs in solution: as it must do in vivo; (b) G1 is a viral attachment protein; and (c) the 50-kDa protein is a candidate host factor essential for TSWV entry. These results provide addi tional support for the role of the 50-kDa thrips protein as a viral recepto r. Additionally these experiments provide the basis for testing saturable b inding and represent an important step toward the first cloning and identif ication of a cellular receptor for a plant virus. (C) 2000 Elsevier Science B.V. All rights reserved.