DETECTION AND ASSIGNMENT OF PROTEINS ENCODED BY RICE BLACK STREAKED DWARF FIJIVIRUS S7, S8, S9 AND S10

The proteins encoded by rice black streaked dwarf fijivirus (RBSDV) ge nomic segments 7-10 (S7-S10) were characterized. Open reading frames ( ORFs) from these segments were expressed as fusion proteins in Escheri chia coli. Antibodies raised against the expressed products were used as probes to determine whether the viral ORFs encode structural protei ns. In Western blots, antibodies to the expressed S8 and S10 products reacted with a core capsid (65 kDa) and a major outer capsid (56 kDa) protein, respectively, while none of the antibodies to S7 and S9 produ cts reacted with structural proteins. Antisera to RBSDV S7 ORF1 and S9 ORF1 each detected a single protein of the predicted size in total pr otein extracts from infected rice plants and viruliferous Laodelphax s triatellus. Immunoelectron microscopy revealed that antibodies to RBSD V S7 ORF1 and RBSDV S9 ORF1 reacted with tubular structures and viropl asm, respectively, in sections of both infected maize plants and virul iferous L. striatellus. Antisera to ORF2 of S7 and S9 failed to detect any proteins in the infected tissue using either Western blotting or immune-electron microscopic techniques.