The complete nucleotide sequence of genome segment 8 (S8) of Nilaparvata lugens reovirus (NLRV) was determined. It consisted of 1802 nucleotides containing a long open reading frame (562 amino acids), which was expressed in Escherichia coli as a fusion protein. The expressed S8 product, a 62K protein, was detected by Western blotting using IgG directed against intact NLRV particles. This result indicates that S8 encodes the major outer capsid protein of NLRV. The protein exhibited 18.6% amino acid sequence identity with the predicted translation product of S10 of rice black-streaked dwarf virus.