Purification and serology of rice tungro spherical and rice tungro bacilliform viruses.

Abstract

Rice seedlings were inoculated by rice green leafhoppers (Nephotettix virescens) that had fed on rice plants infected with both RTBV and RTSV. RTSV-infected plants were identified and selected using antiserum to rice waika virus which is very closely related, if not identical to, RTSV. RTSV was propagated by inoculating rice seedlings using leafhoppers. To multiply RTBV, seedlings were inoculated by leafhoppers that had fed first on plants infected with both RTBV and RTSV, second on anti-RTSV immunoglobulin through membrane, and then on RTBV-infected plants. RTBV and RTSV were purified separately from their respectively infected plants by heating sap for 1 h at 40C, by driselase treatment, and by polyethylene glycol precipitation, differential centrifugations and sucrose density gradient centrifugation. Purified RTBV fractions contained bacilliform particles 30-35 nm in width and 160-220 nm in length. Purified RTSV fractions contained isometric particles 30 nm in diam. Both fractions had UV absorption spectra typical of nucleoprotein. Rabbit antisera obtained had titres of 1/2560 for RTBV and 1/640 for RTSV by the ring-interface precipitin test. The latex test and ELISA specifically detected RTBV and RTSV in leaf extracts. The antisera were virus-specific.