Hepatitis C virus (HCV) is a leading cause of liver disease and liver cancer. Nearly 170 million worldwide are chronically infected with HCV, and current treatment options are effective for only half of the infected. HCV persistence is mediated by the ability of the virus to evade the host innate immune response. While HCV RNA is sensed as foreign by the host cell cytosolic receptor RIG-I, the downstream signaling induced by this detection is suppressed by HCV NS3/4A protease cleavage of MAVS, the RIG-I signaling adaptor. MAVS is localized to mitochondria and peroxisomes, and I have recently found that it is also localized to mitochondrial- associated ER membranes (MAM), which link mitochondria and peroxisomes together into synapses during RIG-I activation. Further, I have found that the HCV NS3/4A protease targets these sites via the NS4A subunit of the protease complex for cleavage of MAVS on the MAM, and not the mitochondria. This data strongly implicates MAVS with MAM localization as the signaling active molecule that drives the innate immune response towards HCV. This proposal will explore the hypothesis that molecules targeted to the MAM during RIG-I pathway activation induce the formation of a MAVS signaling complex by using biochemical and proteomic studies that identify MAM-recruited molecules during the host innate immune response. In addition, the spatial-temporal regulation of NS4A targeting of the NS3/4A protease complex to the MAM for MAVS cleavage and immune evasion will be determined by identifying both the host cell factors and viral components that guide this targeting. These studies will provide valuable insights into the mechanism that activates the switch between the role of NS3/4A in HCV replication and innate immune control. Moreover, they will form the basis for studies to understand how MAM-targeting of MAVS by NS3/4A supports persistent HCV infection. These studies will determine how the MAM organizes both innate immune signaling and the HCV innate immune evasion program. A detailed understanding of these processes will have implications for therapeutic and vaccine design strategies to limit infection by HCV and other RNA viruses that are sensed by the RIG-I pathway.

Public Health Relevance

With more than 170 million people chronically infected worldwide, HCV infection is a global epidemic that results in liver disease and liver cancer. The proposed studies aim to understand the HCV-immune interactions that result in persistent infection in the liver. They will provide insights to develop novel therapeutic and vaccine approaches that could be used to treat or prevent HCV persistence and disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Career Transition Award (K22)
Project #
1K22AI100935-01
Application #
8352240
Study Section
Microbiology and Infectious Diseases B Subcommittee (MID)
Program Officer
Koshy, Rajen
Project Start
2013-12-15
Project End
2015-11-30
Budget Start
2013-12-15
Budget End
2014-11-30
Support Year
1
Fiscal Year
2014
Total Cost
$161,360
Indirect Cost
$11,360
Name
Duke University
Department
Genetics
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705
Beachboard, Dia C; Horner, Stacy M (2016) Innate immune evasion strategies of DNA and RNA viruses. Curr Opin Microbiol 32:113-9
Vazquez, Christine; Horner, Stacy M (2015) MAVS Coordination of Antiviral Innate Immunity. J Virol 89:6974-7
Horner, Stacy M (2015) Insights into antiviral innate immunity revealed by studying hepatitis C virus. Cytokine 74:190-7
Horner, Stacy M; Naggie, Susanna (2015) Successes and Challenges on the Road to Cure Hepatitis C. PLoS Pathog 11:e1004854
Horner, Stacy M; Wilkins, Courtney; Badil, Samantha et al. (2015) Proteomic analysis of mitochondrial-associated ER membranes (MAM) during RNA virus infection reveals dynamic changes in protein and organelle trafficking. PLoS One 10:e0117963
Aligeti, Mounavya; Roder, Allison; Horner, Stacy M (2015) Cooperation between the Hepatitis C Virus p7 and NS5B Proteins Enhances Virion Infectivity. J Virol 89:11523-33
Gokhale, Nandan S; Vazquez, Christine; Horner, Stacy M (2014) Hepatitis C Virus. Strategies to Evade Antiviral Responses. Future Virol 9:1061-1075
Horner, Stacy M (2014) Activation and evasion of antiviral innate immunity by hepatitis C virus. J Mol Biol 426:1198-209