FEATURES ON THE SURFACE OF THE TOBACCO RATTLE TOBRAVIRUS PARTICLE THAT ARE ANTIGENIC AND SENSITIVE TO PROTEOLYTIC DIGESTION

The particle proteins of tobraviruses and tobamoviruses share six sequ ence motifs, two of which are also present in furoviruses and hordeivi ruses. Analyses of four different polyclonal antisera to tobacco rattl e tobravirus by Pepscan revealed that the C-terminal region of the par ticle protein was immunodominant. The N-terminal region and a central region (residues 110-121) were more weakly immunogenic. These results suggest that these regions are exposed externally on the assembled vir us particle. Papain digestion showed that the C terminus can be remove d without apparent structural damage to the particle. The external loc ation of the C-terminal region along the sides of the particle could e xplain some transmission properties of the rod-shaped viruses.