Chikungunya virus (CHIKV) is an emerging mosquito-borne alphavirus responsible for recent major outbreaks of polyarthralgia in countries of the Indian Ocean region. This important human pathogen causes an acute febrile illness characterized by a maculopapular rash and incapacitating arthralgia, which can evolve to chronic arthritis. CHIKV, like other alphaviruses, is transmitted through the bite of an infected mosquito. The virus is currently endemic in Africa, India, and Southeast Asia, but it has recently spread to new areas with attack rates as high as 75 percent. Due to the high prevalence of the CHIKV insect vectors in many parts of the world, the potential for CHIKV to cause significant epidemics in uninfected regions remains high. Little is known about how this virus interacts with the host and the factors that govern tissue tropism. Receptor engagement plays an essential role in viral replication and thus influences the course and outcome of viral disease. To understand the host range, tissue tropism, and virulence of this pathogen, it is critical to elucidate molecular mechanisms of CHIKV attachment and cell entry. Identifying the attachment molecules to which CHIKV binds is a critical step in obtaining a more comprehensive analysis of the envelope-receptor interactions in CHIKV pathobiology. In addition, understanding key determinants of receptor utilization may provide insight into the factors that facilitate transmission between vector and host. This application investigates the viral and cellular determinants of CHIKV cell entry and will further an understanding of mechanisms by which CHIKV enters host cells.
In Specific Aim 1, we will determine the role of N-linked glycosylation sites in the viral envelope proteins in viral replication. Wild-type and glycosylation-site mutant viruses will be produced in mammalian and mosquito cells. The utilization and type of glycosylation at each site will be determined. Cell binding, infectivity, and replication of mutant viruses will be assessed.
In Specific Aim 2, the role of cell-surface glycans in CHIKV replication will be investigated. Types of glycans to which CHIKV binds will be identified by glycan array, and their role in virus binding and cell entry will be analyzed.
In Specific Aim 3, host proteins that mediate viral entry will be identified using proteomic and genomic strategies. Candidate receptors will be analyzed for their role in facilitating virus infection. These studies will provide valuable insights into mechanisms of CHIKV cell entry and further elucidate virus-host interactions at a critical stage of viral replication. Moreover, findings from these studies will provide new insights into the tissue tropism and pathophysiology of CHIKV, which may illuminate new strategies for therapeutic intervention.

Public Health Relevance

Chikungunya virus has caused recent epidemics in which an estimated 2-7 million people in Africa and Asia were infected, and due to the prevalence of mosquito vectors, there exists a serious health threat to naive areas, including the United States. Although Chikungunya virus infection causes a debilitating rheumatic disease that can persist for weeks to months, no licensed vaccines or antiviral therapies are available. The proposed research will enhance an understanding of the viral and host determinants that mediate Chikungunya virus entry, which may foster development of new antivirals that act by blocking this key step in viral infection.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Postdoctoral Individual National Research Service Award (F32)
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Special Emphasis Panel (ZRG1-F13-C (20))
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Repik, Patricia M
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Vanderbilt University Medical Center
Schools of Medicine
United States
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Silva, Laurie A; Dermody, Terence S (2017) Chikungunya virus: epidemiology, replication, disease mechanisms, and prospective intervention strategies. J Clin Invest 127:737-749
Smith, Scott A; Silva, Laurie A; Fox, Julie M et al. (2015) Isolation and Characterization of Broad and Ultrapotent Human Monoclonal Antibodies with Therapeutic Activity against Chikungunya Virus. Cell Host Microbe 18:86-95
Ashbrook, Alison W; Burrack, Kristina S; Silva, Laurie A et al. (2014) Residue 82 of the Chikungunya virus E2 attachment protein modulates viral dissemination and arthritis in mice. J Virol 88:12180-92
Silva, Laurie A; Khomandiak, Solomiia; Ashbrook, Alison W et al. (2014) A single-amino-acid polymorphism in Chikungunya virus E2 glycoprotein influences glycosaminoglycan utilization. J Virol 88:2385-97