Presented at the Neonatal Society 2015 Summer Meeting.
Watson AS, Spalluto CM, Whitwell HJ, Staples KJ, Wilkinson TMA, Madsen J, Clark HW
University of Southampton
Background: Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and hospitalisation of infants in developed countries. Surfactant proteins A and D (SP-A and SP-D) are important innate immune molecules present throughout the airways, particularly in pulmonary surfactant which covers the alveolar epithelium. SP-A and SP-D bind carbohydrates on the surface of pathogens to enhance their neutralisation, agglutination and clearance. Moreover they are important modulators of the inflammatory immune response. The aim of this work was to delineate the interaction of SP-A and SPD with RSV and their capacity to prevent infection of human cells.
Methods: Immortalised human bronchial epithelial cells (AALEB) were infected for 2 hours with a clinical strain of RSV A, which had either been incubated with or without different concentrations of SP-A or SP-D. The virus was left to replicate for 24 hours. RSV infection and replication was determined using RT-qPCR.
Results: Pre-incubation of RSV with both SP-A and SP-D reduced levels of infection of AALEB cells in a dose dependent manner. Pre-incubation with 10μg/ml of SP-A decreased infection of RSV by 57.8% (n=3, P<0.01). Pre-incubation with 10μg/ml of SP-D decreased infection of RSV by 53.7% (n=3, P<0.01). The capacity of SP-A and SP-D to bind RSV attachment (G) and fusion (F) proteins is currently being investigated. Recombinant forms of SP-A and SP-D are also being used to investigate the importance of their oligomeric structure in preventing infection.
Conclusion: Both SP-A and SP-D prevented infection of AALEB cells with RSV A. This may explain the susceptibility of premature neonates with surfactant deficiency to RSV bronchiolitis. Recombinant versions of SP-A and SP-D may have therapeutic potential for the protection of susceptible premature neonates to infection with RSV.
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