Fate of rubella genome ribonucleic acid after immune and nonimmune virolysis in the presence of ribonuclease.

To determine whether rubella virion ribonucleic acid (RNA) becomes accessible to nuclease attack after immune lysis of the viral envelope, virions containing radioactively labeled RNA were examined in three ways with the following results. (i) Incubation of purified virus with heat-inactivated rubella convalescent human serum and guinea pig complement resulted in an increase in acid-soluble RNA. Antibody was required; the reaction was temperature dependent and was blocked by ethylenediaminetetraacetic acid. When exogenous nuclease was added prior to lysis, radioactivity in virions was reduced to 15% of that in unlysed control pellets (ii) Sucrose gradient sedimentation profiles of RNA released from lysed and unlysed virions under controlled conditions showed that the nuclease content of serum-virus mixtures was sufficient to eliminate all RNA of genome size, although degradation was not complete. (iii) Virions were also lysed by unheated human immune sera in the absence of guinea pig complement and by some, but not all, unheated antibody-negative sera.