- Volume 76, Issue 4, 1995

Virus particles were reassembled in vitro from tomato aspermy virus strain V (V-TAV) RNA and a mixture of subunits prepared from V-TAV and 35S-labelled cucumber mosaic virus strain T (T-CMV). Immunodiffusion tests showed that the reassembled particles reacted with polyclonal antisera raised against both V-TAV and T-CMV. Radioactivity was found in the precipitin line formed between the reassembled particles and antiserum raised against T-CMV as well as in the precipitin line formed between the reassembled particles and antiserum raised against V-TAV. This shows that 35S-labelled T-CMV protein subunits were incorporated with V-TAV protein subunits into the same particles. Thus, coat proteins of V-TAV and T-CMV can coassemble and form mixed-subunit capsids in vitro.

The complete nucleotide sequence of rice ragged stunt virus genome segment 9 (S9) was determined. The S9 segment is 1132 nucleotides long and has a long open reading frame starting from the first AUG codon at nucleotide position 14–16 and terminating at a UAG codon located at 1028–1030, which could encode a polypeptide with an M r of 38 600 (P9). The encoded polypeptide has no sequence homology to polypeptides of any other plant reoviruses published previously. An immunological study demonstrated that P9 was the smallest of the structural proteins. The P9 polypeptide was expressed as a fusion protein with maltose binding protein in Escherichia coli. Antisera to purified virions and to the fusion protein reacted with both the bacterially expressed polypeptide and the smallest polypeptide of the purified virus in immunoblotting analyses.