The long-term goal of our research program is to understand mechanisms of human metapneumovirus (HMPV) immunity and pathogenesis and facilitate vaccine development. HMPV is a leading cause of severe lower respiratory infection (LRI) in children and adults worldwide. There is no licensed vaccine against HMPV. Recurrent infections with HMPV and other respiratory viruses such as respiratory syncytial virus (RSV) occur throughout life. Consequently, HMPV and RSV cause severe illness in older adults and persons with underlying conditions such as asthma, immune compromise, and chronic cardiopulmonary disease. Limited induction of CD8+ T cell (TCD8) memory by respiratory viruses may be a contributing factor to reinfection and presents an obstacle to the development of effective vaccines. RSV, influenza, and parainfluenza viruses have been shown to induce TCD8 with impaired cytolytic function and IFN? secretion, but the mechanism of this inhibition was unknown. Similar antigen unresponsiveness termed TCD8 exhaustion is associated with chronic viral infections and cancer. A key mediator of exhausted TCD8 is programmed cell death-1 (PD-1), a negative regulator of T cell activation implicated in maintaining peripheral tolerance and preventing autoimmunity. PD-1 and other inhibitory receptors including LAG-3 are therapeutic targets in chronic infections and cancer. A recognized adverse effect in these patients is respiratory inflammation, likely due to over-activated TCD8. We discovered that HMPV, influenza, and other respiratory viruses induce TCD8 impairment mediated initially by the PD-1 pathway. However, our preliminary data suggest that other inhibitory receptors, including LAG-3, are involved in maintaining lung TCD8 impairment in later stages of exhaustion. We hypothesize that respiratory viruses activate an orchestrated network of inhibitory pathways, which limit the acute TCD8 response and immunopathology, but also limit the induction of effective memory TCD8. These inhibitory pathways are likely natural immunoregulatory responses to limit lung inflammation, but which also limit effective host response and memory. Elucidating these mechanisms would increase understanding of poor immune memory against respiratory viruses and help guide vaccine development.
In Specific Aim 1, we will test the hypothesis that PD-L1 has distinct functions on different cell types in the lung.
In Aim 2, we will define the contribution of other inhibitory receptor pathways to late TCD8 impairment.
In Specific Aim 3, we will test the hypothesis that lung TCD8 impairment programming can be bypassed using non-replicating virus-like particle (VLP) vaccines with local inhibitory receptor blockade. This work will elucidate mechanisms of TCD8 impairment and define the contribution of TCD8 immunoregulatory pathways in the memory response to vaccination and viral respiratory infections. The findings will guide HMPV vaccine development and identify biomarkers of effective TCD8 responses to vaccines. The results of these experiments will be applicable to other respiratory pathogens as well as relevant to respiratory complications of inhibitory receptor blockade therapy.

Public Health Relevance

The goal of this project is to define mechanisms of host immunity to human metapneumovirus (HMPV). HMPV is a leading cause of lung infections worldwide; we found that HMPV and other respiratory viruses induce CD8+ T cell impairment through PD-1 and other inhibitory receptors. The knowledge gained from these experiments will be essential to develop safe and effective vaccines for HMPV and will increase our understanding of how interactions between respiratory viruses and the immune system contribute to disease and protection.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Immunity and Host Defense (IHD)
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Kim, Sonnie
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University of Pittsburgh
Internal Medicine/Medicine
Schools of Medicine
United States
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Hilmes, Melissa A; Daniel Dunnavant, F; Singh, Sudha P et al. (2017) Chest radiographic features of human metapneumovirus infection in pediatric patients. Pediatr Radiol 47:1745-1750
Erickson, John J; Rogers, Meredith C; Tollefson, Sharon J et al. (2016) Multiple Inhibitory Pathways Contribute to Lung CD8+ T Cell Impairment and Protect against Immunopathology during Acute Viral Respiratory Infection. J Immunol 197:233-43
Hastings, Andrew K; Amato, Katherine R; Wen, Sherry C et al. (2016) Human metapneumovirus small hydrophobic (SH) protein downregulates type I IFN pathway signaling by affecting STAT1 expression and phosphorylation. Virology 494:248-56
Gilchuk, Pavlo; Hill, Timothy M; Guy, Clifford et al. (2016) A Distinct Lung-Interstitium-Resident Memory CD8(+) T Cell Subset Confers Enhanced Protection to Lower Respiratory Tract Infection. Cell Rep 16:1800-9
Hastings, Andrew K; Gilchuk, Pavlo; Joyce, Sebastian et al. (2016) Novel HLA-A2-restricted human metapneumovirus epitopes reduce viral titers in mice and are recognized by human T cells. Vaccine 34:2663-70
Wen, Sherry C; Williams, John V (2015) New Approaches for Immunization and Therapy against Human Metapneumovirus. Clin Vaccine Immunol 22:858-66
Cox, Reagan G; Mainou, Bernardo A; Johnson, Monika et al. (2015) Human Metapneumovirus Is Capable of Entering Cells by Fusion with Endosomal Membranes. PLoS Pathog 11:e1005303
Schuster, Jennifer E; Khuri-Bulos, Najwa; Faouri, Samir et al. (2015) Human Metapneumovirus Infection in Jordanian Children: Epidemiology and Risk Factors for Severe Disease. Pediatr Infect Dis J 34:1335-41
Erickson, John J; Lu, Pengcheng; Wen, Sherry et al. (2015) Acute Viral Respiratory Infection Rapidly Induces a CD8+ T Cell Exhaustion-like Phenotype. J Immunol 195:4319-30
Wen, Sherry C; Schuster, Jennifer E; Gilchuk, Pavlo et al. (2015) Lung CD8+ T Cell Impairment Occurs during Human Metapneumovirus Infection despite Virus-Like Particle Induction of Functional CD8+ T Cells. J Virol 89:8713-26

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