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Updated: May 9, 2026
An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
MPO interacts with hRSV particles, contributing to the virucidal effects of NETs against clinical and laboratory hRSV
Leonardo da Silva Pinto1, Ronaldo Silva Alves Junior2, Bruno Rafael Pereira Lopes2
1São Paulo State University (UNESP), School of Sciences, Humanities and Languages, Assis, Brazil.
Abstract:
Human Respiratory syncytial virus (hRSV) mainly affects immunosuppressed patients requiring hospitalization. No specific treatment is financially accessible, and available vaccines do not cover all risk groups. During hRSV infection, there is a robust neutrophilic influx into the airways. hRSV-activated neutrophils release substantial neutrophil extracellular traps (NETs) in lung tissue, comprising DNA, histones, cytosolic, and granular proteins. NETs form mucus buildup in the lungs, compromising respiratory capacity and neutralizing viral particles. Understanding responsible NETs molecules requires improvement. We evaluated NETs interacting with hRSV particles and their contribution to anti-hRSV NET effects. Immunoblotting, immunoprecipitation, and peptide sequencing assays confirmed hRSV binding to a 50-75 kDa NET protein, Myeloperoxidase (MPO). MPO, a microbicide enzyme in NETs, interacts with hRSV, likely at F0 protein (site IV) on the viral surface. Additionally, MPO (32 μM) and NETs (0.4 μg/mL) reduced in vitro replication of clinical (hRSV A and B) and laboratory (Long) hRSV isolates by approximately 30 %, reversible by selective MPO inhibitor (PF-06281355; 48 μM). Thus, MPO contributes to virucidal NET effects on diverse hRSV strains, enhancing comprehension of NETs' role in infection and aiding treatment strategies for respiratory diseases.
Insights
Human Respiratory Syncytial Virus (hRSV) infection involves neutrophil extracellular traps (NETs). Myeloperoxidase (MPO) within NETs shows antiviral properties, reducing hRSV replication and aiding new treatment strategies.
Area of Science:
- Immunology
- Virology
- Respiratory Medicine
Background:
- Human Respiratory Syncytial Virus (hRSV) poses a significant threat, particularly to immunocompromised individuals, with limited accessible treatments and vaccines.
- Neutrophil extracellular traps (NETs), composed of DNA and proteins, are released during hRSV infection and contribute to lung pathology and viral neutralization.
- The specific molecules within NETs responsible for anti-hRSV effects require further elucidation.
Purpose of the Study:
- To investigate the interaction between NETs and hRSV particles.
- To identify NET components contributing to anti-hRSV activity.
- To assess the therapeutic potential of identified NET molecules against hRSV.
Main Methods:
- Immunoblotting, immunoprecipitation, and peptide sequencing were employed to identify hRSV-binding proteins within NETs.
- In vitro assays were conducted to evaluate the impact of Myeloperoxidase (MPO) and NETs on hRSV replication.
- The effect of a selective MPO inhibitor was assessed to confirm MPO's role.
Main Results:
- Myeloperoxidase (MPO), a 50-75 kDa protein found in NETs, was confirmed to bind to hRSV, likely at the F0 protein (site IV).
- Both MPO (32 μM) and NETs (0.4 μg/mL) demonstrated a significant reduction (approximately 30%) in the in vitro replication of various hRSV strains.
- This antiviral effect was reversible by a selective MPO inhibitor (PF-06281355; 48 μM), confirming MPO's contribution.
Conclusions:
- Myeloperoxidase (MPO) is a key virucidal component of NETs that effectively targets diverse hRSV strains.
- Understanding MPO's role in NETs enhances our comprehension of the immune response during hRSV infection.
- Targeting MPO presents a promising avenue for developing novel therapeutic strategies against hRSV and other respiratory viral diseases.
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