IMPORED - Intravital imaging of polymicrobial respiratory diseases

Respiratory infections are one the leading causes of morbidity and mortality worldwide. Amongst the major respiratory pathogens, influenza virus and Streptococcus pneumoniae (the pneumococcus), have a health impact that is also responsible for thousands of millions of public money lost every year. Typically, scientific studies have focused on infections with single pathogens. However, it has been demonstrated that, in some cases, co-infection with a particular combination of pathogens results in a more severe clinical outcome compared with infection with either pathogen alone. Nevertheless, the mechanisms by which influenza co-infection may facilitate pneumococcal secondary infections remain unclear.This proposal regards the investigation of the host-pathogen interactions upon co-infection with influenza virus and S. pneumoniae, using state-of-the-art molecular techniques (microbiome analysis, microarray analysis) and intravital microscopy methods (2-photon microscopy) in the mouse model. To this end, two aims are proposed. The first aim of the project is to characterise the molecular mechanisms that lead to the transition from normal microbiota to an infected state in the upper respiratory tract, taking into account the host-pathogen interactions that lead to infection. We will use the well-studied association between influenza virus and Streptococcus pneumoniae infections to inform our investigation of their interaction with the upper respiratory tract microbiome and the host response. We will develop a predictive model of how the transcriptome and microbiome signature of the host may be affected in response to a challenge (for instance an influenza infection) so that we can analyse the possibility that this perturbation could lead to a secondary, more dangerous, disease such as pneumococcal infection.In the second aim we will examine in vivo the effects that the molecular mechanisms identified in the previous aim have in the establishment of a pneumococcal secondary infection. We will develop an intravital 2-photon microscopy model of the mouse trachea and different fluorescent strains of influenza and pneumococcus will be produced to visualize their interaction with the host tissue. This technique will allow us the monitor the dynamics of the co-infection in real time.