Characterization of a Replicating Mammalian Orthoreovirus with Tetracysteine-Tagged μNS for Live-Cell Visualization of Viral Factories.

Within infected host cells, mammalian orthoreovirus (MRV) forms viral factories (VFs), which are sites of viral transcription, translation, assembly, and replication. The MRV nonstructural protein μNS comprises the structural matrix of VFs and is involved in recruiting other viral proteins to VF structures. Previous attempts have been made to visualize VF dynamics in live cells, but due to current limitations in recovery of replicating reoviruses carrying large fluorescent protein tags, researchers have been unable to directly assess VF dynamics from virus-produced μNS.

Mammalian Orthoreovirus Factories Modulate Stress Granule Protein Localization by Interaction with G3BP1.

Mammalian orthoreovirus (MRV) infection induces phosphorylation of translation initiation factor eIF2α, which promotes the formation of discrete cytoplasmic inclusions, termed stress granules (SGs). SGs are emerging as a component of the innate immune response to virus infection, and modulation of SG assembly is a common mechanism employed by viruses to counter this antiviral response. We previously showed that MRV infection induces SGs early and then interferes with SG formation as infection proceeds.

Efficient assembly of ribosomes is inhibited by deletion of bipA in Escherichia coli.

Unlabelled: The bacterial BipA protein belongs to the EF-G family of translational GTPases and has been postulated to be either a regulatory translation factor or a ribosome assembly factor. To distinguish between these hypotheses, we analyzed the effect of bipA deletion on three phenotypes associated with ribosome assembly factors: cold sensitivity, ribosome subunit distribution, and rRNA processing. We demonstrated that a ΔbipA strain exhibits a cold-sensitive phenotype that is similar to, and synergistic with, that of a strain with a known ribosome assembly factor, deaD.