The arthropod-vectored alphavirus eastern equine encephalitis virus (EEEV) is one of the most virulent viruses endemic to the United States (US), causing devastating disease and mortality in a high percentage of infected humans and equines. Due to its extreme neurovirulence, widespread distribution in the eastern US and potential for use as a bioweapon, it is categorized as a Select Agent virus and NIH Category B Priority Pathogen. Yet, no antiviral drugs or licensed human vaccines are available to combat this virus and it is critically understudied. The virus-receptor interaction represents a target fo antiviral therapeutics and can be used in rational design of vaccine vectors. Heparan sulfate (HS) is a sulfated polysaccharide identified as an attachment receptor for multiple alphavirus and flavivirus laboratory strains but its relevance to viruses in nature is in question because its use as a receptor is possibly an artifact of adaptation to in vitro growth. To address this question, we compared the E2 attachment protein amino acid sequence between a HS binding EEEV laboratory strain and over 60 EEEV strains, including viruses sequenced directly from unamplified field samples of animal tissues. This analysis confirmed that HS is a receptor for naturally circulating EEEV. By mutagenesis of the EEEV attachment protein eliminating the HS binding phenotype, we determined that HS binding was responsible for multiple unique aspects of EEEV disease in vertebrates including extreme neurovirulence, limited spleen replication and suppression of cytokines/chemokines involved in innate and adaptive immune responses. This suggests that HS binding promotes EEEV replicative fitness in vivo. The experiments in this application will investigate the role of HS binding in EEEV disease and tissue targeting in vertebrate and mosquito hosts identifying points in the arbovirus replication/transmission cycle vulnerable to therapeutic intervention and provide the basis for the rational design of anti-EEEV vaccines.

Public Health Relevance

Eastern equine encephalitis virus (EEEV) is a highly human-virulent arthropod-vectored alphavirus endemic throughout the eastern United States. No antiviral drugs or licensed vaccines are available for EEEV or other encephalitic alphaviruses. The virus-receptor interaction represents an important target for antiviral therapeutics and can be used in refinement of vaccine vectors. We have determined that heparan sulfate (HS) is a receptor for naturally circulating EEEV strains. The experiments in this application will investigate the role of HS binding in EEEV disease and tissue targeting in animal hosts which will guide future testing of antiviral drugs and provide the basis for the rational design of anti-EEEV vaccines.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01AI095436-03
Application #
8608475
Study Section
Virology - B Study Section (VIRB)
Program Officer
Repik, Patricia M
Project Start
Project End
Budget Start
Budget End
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Genetics
Type
Schools of Medicine
DUNS #
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Bhalla, Nishank; Sun, Chengqun; Metthew Lam, L K et al. (2016) Host translation shutoff mediated by non-structural protein 2 is a critical factor in the antiviral state resistance of Venezuelan equine encephalitis virus. Virology 496:147-65
Hyde, Jennifer L; Chen, Rubing; Trobaugh, Derek W et al. (2015) The 5' and 3' ends of alphavirus RNAs--Non-coding is not non-functional. Virus Res 206:99-107
Trobaugh, Derek W; Ryman, Kate D; Klimstra, William B (2014) Can understanding the virulence mechanisms of RNA viruses lead us to a vaccine against eastern equine encephalitis virus and other alphaviruses? Expert Rev Vaccines 13:1423-5
Sun, Chengqun; Gardner, Christina L; Watson, Alan M et al. (2014) Stable, high-level expression of reporter proteins from improved alphavirus expression vectors to track replication and dissemination during encephalitic and arthritogenic disease. J Virol 88:2035-46
Trobaugh, Derek W; Gardner, Christina L; Sun, Chengqun et al. (2014) RNA viruses can hijack vertebrate microRNAs to suppress innate immunity. Nature 506:245-8
Gardner, Christina L; Choi-Nurvitadhi, Jo; Sun, Chengqun et al. (2013) Natural variation in the heparan sulfate binding domain of the eastern equine encephalitis virus E2 glycoprotein alters interactions with cell surfaces and virulence in mice. J Virol 87:8582-90
Gardner, Christina L; Burke, Crystal W; Higgs, Stephen T et al. (2012) Interferon-alpha/beta deficiency greatly exacerbates arthritogenic disease in mice infected with wild-type chikungunya virus but not with the cell culture-adapted live-attenuated 181/25 vaccine candidate. Virology 425:103-12