| Properties of particles in sap |
TIP: 45-50 . LIV: 10 days (at 4
Centigrade). DEP: log10 minus 3-4 (in sap from rice leaves). Infectivity of
sap not changed by treatment with di-ethyl ether. Leaf sap contains many
virions. |
| Purification method |
| |
| Particle morphology |
Virions isometric; not enveloped; 70
nm in diameter; angular in profile; with a conspicuous capsomere arrangement.
|
| Physical properties |
Two sedimenting components in
purified preparations; sedimentation coefficient 510 S. Density 1.26 g cm-3
in CsCl (T), or 1.38 g cm-3 in CsCl (M1), or 1.43 g cm-3 in CsCl (M2), or 1.46
g cm-3 in CsCl (B). A260/A280 ratio 1.4. |
| Biochemical properties |
Virions contain 20 % nucleic acid; 80 % protein. |
Genome consists of RNA; double-stranded;
linear. Total genome size 25.13 kb (pairs). Genome of 12 parts (named S1-12);
largest genome part 4.354 kb (pairs); the 2nd largest 3.385 kb (pairs);
the 3rd largest 3.195 kb (pairs); the 4th largest 2.468 kb (pairs); the 5th
largest 2.57 kb (pairs); the 6th largest and other parts 1.699 kb (pairs);
also 1.696, 1.424, 1.305, 1.319, 0.887 and 0.828 kb pairs). Genomic nucleic
acid isolated by Kimura et al. Base composition 21.8-22.8 % G; 27.8-28.4 % A;
21.4-21.6 % C; 28-28.2 % U. Base composition of ds genome 42.3-48.1 %
(G + C). 5กไ terminus of RNA has an unusual type; shows the sequence of GGCA
or GGUA. Infectivity lost when deproteinised with phenol or detergent. Poly
A region absent. |