Induction of innate immunity in lungs with virus-like nanoparticles leads to protection against influenza and Streptococcus pneumoniae challenge

Nanoparticles composed of the coat protein of a plant virus (papaya mosaic virus; PapMV) and a single-stranded RNA (ssRNA) trigger a strong innate immune stimulation in the lungs of the animals a few hours following instillation. A rapid recruitment of neutrophils, monocytes/macrophages and lymphocytes follows. This treatment was able to provide protection to an influenza challenge that lasts at least 5 days. Protection could be recalled for longer periods by repeating the instillations once per week for more than 10 weeks. The treatment also conferred protection to a lethal challenge with Streptococcus pneumoniae – the major cause of bacterial pneumonia. Finally, we also showed that the nanoparticles could be used to treat mice infected with influenza and significantly decrease morbidity. These data strengthen the potential for using PapMV nanoparticles as non-specific inducers of the innate immune response in lungs during viral pandemics or to combat bioterrorist attack.From the Clinical EditorIn this study, virus-like nanoparticles were utilized to induce innate immune responses in a mouse model. They were also demonstrated to provide enhanced immune responses during actual pneumonia and ongoing viral infection. Strategies like this may become very helpful in human applications, including bioterrorism countermeasures.

Graphical AbstractNanoparticles made of the coat protein (CP) of the papaya mosaic virus (PapMV) and a synthetic RNA are able to trigger innate immunity in the lung of animals treated by the intranasal route (I.N.). This stimulation leads to the induction of the antiviral and the anti-bacterial mucosal response in lungs. Therefore, treated animals with PapMV nanoparticles are protected to a lethal challenge with influenza virus (flu) or Streptococcus pneumoniae (major cause of bacterial pneumoniae).Figure optionsDownload high-quality image (84 K)Download as PowerPoint slide