Effect of neutrophil extracellular traps in the inhibition of human respiratory syncytial virus infection/replication

Abstract

Worldwide, it is estimated 12 million cases of severe lower respiratory tract infection, including respiratory syncytial virus (HRSV) which contributes to the development of bronchiolitis, pneumonia, obstructive pulmonary infections. Neutrophils are the predominant phagocytes in these infections, contributing to the elimination of pathogens by classical microbicidal mechanisms. Neutrophils produce extracellular traps (NETs), consisting of genomic DNA associated with nuclear/granular proteins that capture and eliminate different microorganisms. These structures are generated from different stimuli, including hRSV. The presence of NETs was detected in lung tissue of infected individuals hRSV but their importance in infection by this virus has not yet been elucidated. The objective of this study is to investigate whether the NETs have effect on the infection/replication of hRSV virus. For this purpose, in vitro and in silico approaches will be used. NETs generated under the PMA stimulation will be tested in different antiviral protocols (pretreatment, virucidal, post-treatment) targeting Hep-2 cells infected or not by hRSV virus. In addition, same groups will receive NETs + Palivizumab (monoclonal anti-RSV antibody). The cell protection (or inhibition of infection/replication) will be measured by the salt MTT assays. Promising results (e 50% cell protection) are analyzed using plaque reduction assays. The determination of CC50 and EC50 values will enable to calculate the Selectivity Index, which indicates how promising it is the antiviral NETs activity. Finally, a possible interaction between NETs and F protein from hRSV will be evaluated by molecular docking studies. The results obtained with the development of this design will help in the understanding of beneficial or pathogenic involvement of neutrophils during the immune response in hRSV infection. (AU)