Localization of rubella virus core particles in vero cells

Rubella virus (RV) infection induces a variety of morphological changes in the host cell including the modification of lysosomes to produce "replication complexes" and the alteration of mitochondrial morphology and distribution. The morphogenesis of RV was further characterized with particular emphasis on the localization of RV core particles. Thin-section electron microscopy (TSEM) studies indicated that RV core-like particles, measuring approximately 33 nm in diameter, were found associated with RV replication complexes. Immunogold-labeling electron microscopy (EM) using monoclonal antibodies to RV capsid proteins confirmed that these particles were viral cores. RV core particles were also detected in association with mitochondria as observed by TSEM and immunogold-labeling EM using monoclonal antibodies to capsid or polyclonal antibodies to RV virions. The results of this study indicate that the localization of RV core particles in relation to replication complexes is similar to that found for the alphaviruses. However, the association of RV core particles with mitochondria appears unique within the family Togaviridae.