Formation of an RNA heterodimer upon heating of nodavirus particles

Flock House virus is a small icosahedral insect virus of the family Nodavir idae. Its genome consists of two positive-sense RNA molecules, which are be lieved to be encapsidated into a single viral particle. However, evidence t o support this claim is circumstantial. Here we demonstrate that exposure o f nodavirus particles to heat causes the two strands of viral RNA to form a stable complex, directly establishing that both RNAs are copackaged into o ne virion. The physical properties of the RNA complex, the effect of heat o n the particles per se, and the possible relevance of these findings to the nodavirus life cycle are presented.