Morphogenesis of aura virus.

Aura virus, a member of the Western equine-encephalitis-Whataroa subgroup of group A arboviruses, was studied by electron microscopy in suckling mouse brain and chick embryo cultured cells. Virus precursors, budding particles, and complete virus particles were first detected 10 hr after infection in chick embryo cells and 24 hr after inoculation in mouse brain. Virus precursors were generally seen aligned along cytomembranes, and were less frequently seen closely associated with viroplasm-like foci, tubular aggregates, or scattered in the cytoplasmic matrix without an apparent connection to any other structure. The assembly of mature virus was observed to take place by a budding process of the virus precursor from the plasma membrane into the extracellular space, and from the cytoplasmic membranes into the lumina of vacuoles and cisternae. It was demonstrated that the endoplasmic reticulum participates in the assembly of intracellular virions. Indirect evidence was found to indicate that the Golgi complex may also form mature virus. Aura virions had a size, shape, and structure similar to those of the previously described group A arboviruses.