Characterization of Respiratory Microbiota in Susceptibility to Viral Respiratory Infections

The role of the nasopharyngeal mucosal microbiota has recently been emphasized in respiratory diseases. The hypothesis that respiratory infections are linked to an imbalance of the nasopharyngeal microbiota has recently emerged and some studies show a link between the respiratory microbiota, the susceptibility to viral respiratory infections and the severity induced. In a preliminary work on the respiratory microbiota from 225 patients and 48 controls, the investigators found a decrease in the richness and biodiversity of the nasopharyngeal microbiota in patients with a respiratory viral infection as well as an enrichment of their respiratory flora in pathogenic bacteria. Interestingly, these recent years, the development of qPCR for virus diagnosis showed a substantial proportion of asymptomatic carriers of viruses suggesting that the nasopharyngeal microbiota may play a critical role in the genesis and clinical expression of viral respiratory infection, challenging Koch's postulate. The principal objectives of this study are to compare the respiratory microbiota between symptomatic patients with respiratory viral infection and asymptomatic carrier of virus. The aim is to determine the existence of respiratory microbiota profiles associated with the occurrence of viral respiratory infections influencing the clinical expression of virus and to determine the role of the respiratory microbiota in the occurrence of bacterial superinfection which will justify an early antibiotic treatment. The investigators will include 35 symptomatic patients with viral respiratory infection harboring positive qPCR for respiratory virus (influenza A or B, RSV, rhinovirus, metapneumovirus), 35 asymptomatic patients with positive qPCR for respiratory virus and 30 healthy subjects (controls). A pharyngeal and a nasal swabs will be performed for each patient. All the samples will be analyse by culturomics and metagenomic. Culturomic is a high-throughput culture strategy based on the multiplication of culture conditions coupled with the rapid identification of bacteria by MALDI-TOF (Matrix-Assisted Laser Desorption / Ionization-Time-Of-Flight) mass spectrometry.Metagenomics is an high throughput sequencing and will be performed using Miseq ( Illumina technology) targeting the V3-V4 hypervariable regions of the 16S RNA gene. The precise characterization of the respiratory microbiota in patients with viral respiratory infections is still incomplete. Our work is original because it will combine innovative and complementary techniques of culturomics and metagenomics for the exhaustive study of the respiratory microbiota associated with respiratory viral disease.