All ETDs from UAB

Advisory Committee Chair

Colleen B Jonsson

Advisory Committee Members

Casey D Morrow

Peter E Prevelige

Elizabeth S Sztul

Tim M Townes

Document Type

Dissertation

Date of Award

2009

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Old World and New World hantaviruses, family Bunyaviridae, mature intracellularly within cellular compartments. Although it is generally accepted they assemble and bud in the Golgi apparatus the site remains controversial for New World hantaviruses, because some studies have raised the possibility of their maturation at the plasma membrane. Furthermore, the site of assembly hantaviruses still remains undetermined. The nucleocapsid (N) protein has been proposed to play a key role in facilitating assembly. To gain insight into the assembly pathways of Old World hantaviruses, we examine the intracellular trafficking of the Hantaan (HTN) virus N protein. We show progressive redistribution of the HTN virus N protein in Vero E6 cells from the cell periphery to the perinuclear region during infection. Using confocal microscopy, we show that the HTN virus N protein specifically targets the endoplasmic reticulum-Golgi intermediate compartment (ERGIC). We did not observe colocalization of N protein with actin microfilaments, suggesting that targeting is actin independent and may use other cytoskeletal structures. Interestingly, expression of HTN virus N protein also targeted to the perinuclear region independent of other viral components, which suggests the N protein may contain an intrinsic signal sufficient for subcellular targeting. Herein, we show that the region of amino acids 270-300 may function to influence perinuclear targeting. Hantaviruses cause two human diseases, hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. Although pathogenesis is believed to be immunologically mediated, the underlying mechanism is unknown. Numerous reports have shown elevated levels of proinflammatory and inflammatory cytokines in human sera from patients infected with hantaviruses. We show a direct relationship between the HTN virus N protein and modulation of apoptosis. Interestingly, we observed elevated caspase-7, and -8, but not -9 activity in cells expressing N protein mutants lacking amino acids 270-330. We also observed that the HTN virus N protein is capable of circumventing the immune signaling pathway of the tumor necrosis factor receptor (TNF-R) by interfering with the nuclear import of nuclear factor kappa B (NF-ĸB).

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