Mechanisms of Flavivirus Antagonism of Innate Immune Signaling in Human Dendritic Cells Public
Bowen, James R (2017)
Published
Abstract
West Nile virus (WNV) is a neurotropic flavivirus that remains a leading cause of mosquito-borne encephalitis in the United States. Zika virus (ZIKV), which is closely related to WNV, is an emerging mosquito-borne flavivirus that has sparked a global public health crisis due to a causal linkage to severe neonatal birth defects. Previous work has suggested that dendritic cells (DCs) are important cellular targets during infection with related flaviviruses, including dengue, yellow fever, and Japanese encephalitis viruses. However, the contributions of human DCs during WNV or ZIKV infection remains poorly understood. Here, we utilized primary human cells to demonstrate that monocyte-derived DCs (moDCs) support productive viral replication following infection with WNV and ZIKV. Using a systems biology approach, STAT5 was identified as a regulator of DC activation that was not activated during WNV or ZIKV infection. Consequently, molecules involved in antigen presentation and T cell activation were minimally induced during WNV and ZIKV infection, and functionally, WNV-infected moDCs dampened allogeneic T cell proliferation. Mechanistically, WNV and ZIKV blocked tyrosine phosphorylation of STAT5, and to a lesser extent STAT1 and STAT2, through impairment of Tyk2 and JAK1 activation. ZIKV, but not WNV, also selectively blocked type I IFN protein translation, without affecting the up-regulation of other antiviral proteins. Combined, our studies use primary human cells to reveal novel mechanisms used by WNV and ZIKV to subvert DC activation during productive infection within human moDCs.
The mechanisms and cell types involved in transplacental transmission of ZIKV are poorly understood. Here, we utilized primary human cells isolated from villous tissue of full-term placentae to demonstrate that ZIKV productively replicates within primary human placental macrophages, known as Hofbauer cells (HCs). ZIKV also infected cytotrophoblasts, although viral replication was delayed and more limited. ZIKV infection of HCs promoted up-regulation of T cell co-stimulatory molecules, production of pro-inflammatory cytokines, type I IFN secretion, and strong antiviral gene expression. Combined, our findings support a mechanism of transplacental transmission where ZIKV gains access to the developing fetus by directly infecting placental cells and disrupting the placental barrier.
Table of Contents
TABLE OF CONTENTS Distribution agreement
i
Approval sheetii
Abstract coveriii
Abstractiv
Cover pagev
Acknowledgementsvi
Table of Contentsvii
List of Figures and Tablesx
Abbreviationsxii
Chapter 1: Introduction1
Part 1. Neurotropic flaviviruses 1A) West Nile virus
1 a) WNV disease in humans 2 b) WNV pathogenesis 3 c) WNV immunity 4B) Zika virus
5a) ZIKV is causally linked to birth defects during congenital infection
7 b) Transplacental transmission of ZIKV 8c) ZIKV targets neuroprogenitor cells in the fetal brain
10 d) ZIKV immunity 11Part 2. Innate immune signaling during WNV and ZIKV infection
14A) RIG-I like receptor signaling
15
a) MAVS is critical for host control of WNV infection
b) Non-redundant roles of RIG-I and MDA5 during WNV infection
c) RLR signaling during ZIKV infection
B) TLR and MyD88-dependent signaling
16
18
19
20
a) MyD88-dependent signaling restricts WNV replication within the CNS
b) IL-1 signaling promotes WNV clearance from the CNS
20
21
c) TLR signaling through MyD88 plays a minor role in control of WNV infection
22
d) TLR-3 plays a CNS-intrinsic role during WNV infection
e) TLR-3 signaling limits neuroprogenitor growth during ZIKV infection
23
24
C) Type I interferon signaling
a) Type I IFN signaling restricts WNV infection
b) Deficiency in type I IFN signaling as a mouse model for ZIKV infection
25
25
25
D) Type III interferon signaling
a) Type III IFN signaling regulates BBB permeability during WNV infection
b) Type III IFN signaling protects human placental trophoblasts from ZIKV infection
26
27
27
Part 3. Systems biology approaches unravel the host antiviral response
28A) The antiviral landscape
28
B) Organism level
30
a) Host genetics impacts Influenza A Virus pathogenesis
32
b) Modeling determinants of symptomatic West Nile Virus infection
33
c) Development of an improved small animal pathogenesis model for Ebola Virus infection
34
C) Tissue level
36
a) Transcriptomics uncovers determinants of West Nile virus tissue tropism
36
b) Transcriptomics enhances our understanding of severe Influenza A virus infection
37
c) Transcriptomics defines human antiviral immunity to Dengue Virus
40
D) Cell level
41 a) Single cell transcriptomics 41b) Single cell RNAseq reveals bimodal expression of immune response genes in dendritic cells
42c) Single cell analysis reveals subversion of type I IFN production in infected and bystander cells during rotavirus infection
43 d) Outlook for the coming age of single cell analysis 45E) Conclusion- Systems biology as a tool to chart the antiviral landscape
46Chapter 2: Systems biology reveals West Nile virus antagonism of STAT5 signaling during infection of human dendritic cells
50
A) Abstract
51
B) Author Summary
52
C) Introduction
53
D) Results
55
E) Discussion
68
F) Experimental procedures
75
G) Figures and legends
82
H) Tables and legends
106
Chapter 3: Zika virus antagonizes type I interferon responses during infection of human dendritic cells
107
A) Abstract
108
B) Author Summary
109
C) Introduction
110
D) Results
113
E) Discussion
130
F) Experimental procedures
138
G) Figures and legends
146
H) Tables and legends
173
Chapter 4: Zika virus infects human placental macrophages
178
A) Abstract
179
B) Introduction
179
C) Results
181
D) Discussion
188
E) Experimental procedures
191
F) Figures and legends
195
G) Tables and legends
207
Chapter 5: General discussion and future directions
211
References
228
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