Dissertation/Thesis Abstract

The Function of Reovirus Non-structural Protein σ1s In Viral Replication and Dissemination
by Phillips, Matthew, Ph.D., University of Arkansas for Medical Sciences, 2018, 206; 10812406
Abstract (Summary)

Viruses must be able to traffic from initial sites of infection to secondary sites to cause disease. Mammalian orthoreovirus (reovirus) requires non-structural protein σ1s to disseminate via the blood. However, it is unknown how σ1s facilitates hematogenous dissemination. We have found that σ1s supports effective T1L reovirus replication in multiple cell types, including SV-40 immortalized endothelial cells (SVECs). In SVECs, σ1s is dispensable for viral RNA synthesis and protein stability but functions to support optimal viral protein expression, suggesting that σ1s functions at the level of viral protein synthesis. In contrast, T3D reovirus is less dependent on σ1s. While both T3D and T1L σ1s promote viral protein expression and replication in the T1L genetic background, reoviruses with the T3D genetic background do not need σ1s for initial rounds of replication and protein expression in SVECs. Although σ1s does not function as a type-I interferon (IFN-I) antagonist, removal of IFN-I signaling rescues σ1s-null reovirus replication, but only partially rescues viral protein expression. This indicates that σ1s contributes to reovirus resistance of IFN-I responses, but there is an IFN-I-independent mechanism by which σ1s supports viral protein expression. In C57BL/6 mice, σ1s is required for T1L dissemination after oral inoculation as only the WT virus can be recovered at high titers. However, in IFN-I ?/? receptor subunit 1 knockout mice ( IFNAR1-/-) σ1s-null titers in secondary organs are comparable to the WT virus, suggesting that IFN-I responses act as a barrier to σ1s-null reovirus dissemination. Finally, we used the IFN-I sensitivity of the σ1s-null reovirus to dissect pathways of reovirus dissemination using Cre-lox technology to delete IFNAR1 in lymphatic endothelial cells (LEC). In parental mouse strains and littermate controls, σ1s is required for reovirus dissemination after oral inoculation. However, in LEC-specific IFNAR1 knockout mice, comparable titers of σ1s-null and WT reovirus are recovered in secondary organs. This suggests that LECs are a major cell type that mediate reovirus dissemination. These studies provide new insights into the function of σ1s during reovirus replication and dissemination and highlight new avenues for studies of mechanisms by which reoviruses spread in the host.

Indexing (document details)
Advisor: Boehme, Karl W.
Commitee: Forrest, Craig, Kelley, Thomas, Liu, Jia, Zhang, Xuming
School: University of Arkansas for Medical Sciences
Department: Microbiology and Immunology
School Location: United States -- Arkansas
Source: DAI-B 79/10(E), Dissertation Abstracts International
Subjects: Virology
Keywords: Dissemination, Non-structural, Reovirus, Replication, Translation, Viremia
Publication Number: 10812406
ISBN: 9780438037496
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