Morphogenesis of Aura Virus

Abstract

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.

A new Aura virus isolate in Brazil shows segment duplication in the variable region of the nsP3 gene

“…In addition, the virions seen in the TEM presented an average size of 55.0 nm (Fig. 1 ) in accordance with a previous report on AURAV [ 12 ].…”

“…In their work, AURAV was titrated in BHK-21 cells through plaque assay [ 14 ]. On the other hand, Lascano et al [ 12 ] carried out a study on the morphogenesis of Aura virus particles in CEF and the brains of newborn mice infected through intracerebral inoculation. Newborn mice intracerebral inoculation was also used for virus titration in this later case [ 12 ].…”

Viroplasm and large virus-like particles in the dinoflagellateGymnodinium uberrimum

“…The extensive Golgi network in Gymnodinium uberrimum associated with the viroplasm and VLPs suggests that membranes and other products of this complex may provide viral precursor material and participate in the process of VLP assembly. The Golgi apparatus has already been implicated in this process in the formation of Aura virus (LAscANO et al 1969). Furthermore, nerve cells infected with equine encephalomyelitis virus exhibit an increased number of Golgi complexes and depletion of polysomes (GA~cIA-TAMAYO 1971); similar qualitative observations were made for Gymnodinium uberrimum in this report.…”

Acid Phosphatase Activity in Mouse Brain Infected with Venezuelan Equine Encephalomyelitis Virus

“…Viroplasmic foci, similar to those observed in the nerve cells of VEE-inoculated newborn mice, have been rarely reported in cells infected by an arbovirus (8,15); however, masses of viroplasm were recently described in tissue-cultured cells infected with VEE virus (4). The development of Eastern equine encephalitis virus (11) and Semliki Forest virus (5) in mouse brain has been recently described; these observations are similar to my results; in spite of this, no masses of viroplasm in the cytoplasm of nerve cells were demonstrated.…”

“…Previous light microscopic studies have revealed acid phosphatase activity in tissue culture cells infected with several viruses (2). Augmentation of acid hydrolytic enzymes was considered to be a defensive reaction of the cells to digest viral proteins (8). Acid phosphatase activity in the endoplasmic reticulum and perinuclear cistern of nerve cells in VEE virus infection suggested increased production of this enzyme in the ribosomes.…”