Isolation, Purification, and Serology of Rice Tungro Bacilliform and Rice Tungro Spherical Viruses. Pepito Q. Cabauatan, International Rice Research Institute, P. O. Box 933, Manila, Philippines. Hiroyuki Hibino, International Rice Research Institute, P. O. Box 933, Manila, Philippines. Plant Dis. 72:526-528. Accepted for publication 24 November 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0526.

Rice seedlings were inoculated by rice green leafhoppers (Nephotettix virescens) that had fed on rice plants infected with both rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). Rice tungro spherical virus-infected plants were identified and selected using antiserum to rice waika virus which is very closely related, if not identical to, RTSV. Rice tungro spherical virus 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. Rice tungro bacilliform virus and RTSV were purified separately from their respectively infected plants by heating sap 1 hr at 40 C, 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 diameter. Both fractions had UV absorption spectra typical of nucleoprotein. Rabbit antisera obtained had titers of 1/2,560 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.