Screening antivirals with a mCherry-expressing recombinant bovine respiratory syncytial virus: a proof of concept using cyclopamine

Bovine respiratory syncytial virus (BRSV) is a pathogenic pneumovirus and a major cause of acute respiratory infections in calves. Although different vaccines are available against BRSV, their efficiency remains limited, and no efficient and large-scale treatment exists. Here, we developed a new reverse genetics system for BRSV expressing the red fluorescent protein mCherry, based on a field strain isolated from a sick calf in Sweden. Although this recombinant fluorescent virus replicated slightly less efficiently compared to the wild type virus, both viruses were shown to be sensitive to the natural steroidal alkaloid cyclopamine, which was previously shown to inhibit human RSV replication. Our data thus point to the potential of this recombinant fluorescent BRSV as a powerful tool in preclinical drug discovery to enable high throughput compound screening

Paradigms of Lung Microbiota Functions in Health and Disease, Particularly, in Asthma

Improvements in our knowledge of the gut microbiota have broadened our vision of the microbes associated with the intestine. These microbes are essential actors and protectors of digestive and extra-digestive health and, by extension, crucial for human physiology. Similar reconsiderations are currently underway concerning the endogenous microbes of the lungs, with a shift in focus away from their involvement in infections toward a role in physiology. The discovery of the lung microbiota was delayed by the long-held view that the lungs of healthy individuals were sterile and by sampling difficulties. The lung microbiota has a low density, and the maintenance of small numbers of bacteria seems to be a critical determinant of good health. This review aims to highlight how knowledge about the lung microbiota can change our conception of lung physiology and respiratory health. We provide support for this point of view with knowledge acquired about the gut microbiota and intestinal physiology. We describe the main characteristics of the lung microbiota and its functional impact on lung physiology, particularly in healthy individuals, after birth, but also in asthma. We describe some of the physiological features of the respiratory tract potentially favoring the installation of a dysbiotic microbiota. The gut microbiota feeds and matures the intestinal epithelium and is involved in immunity, when the principal role of the lung microbiota seems to be the orientation and balance of aspects of immune and epithelial responsiveness. This implies that the local and remote effects of bacterial communities are likely to be determinant in many respiratory diseases caused by viruses, allergens or genetic deficiency. Finally, we discuss the reciprocal connections between the gut and lungs that render these two compartments inseparable

Transcriptomic Analysis of Host Immune and Cell Death Responses Associated with the Influenza A Virus PB1-F2 Protein

Airway inflammation plays a major role in the pathogenesis of influenza viruses and can lead to a fatal outcome. One of the challenging objectives in the field of influenza research is the identification of the molecular bases associated to the immunopathological disorders developed during infection. While its precise function in the virus cycle is still unclear, the viral protein PB1-F2 is proposed to exert a deleterious activity within the infected host. Using an engineered recombinant virus unable to express PB1-F2 and its wild-type homolog, we analyzed and compared the pathogenicity and host response developed by the two viruses in a mouse model. We confirmed that the deletion of PB1-F2 renders the virus less virulent. The global transcriptomic analyses of the infected lungs revealed a potent impact of PB1-F2 on the response developed by the host. Thus, after two days post-infection, PB1-F2 invalidation severely decreased the number of genes activated by the host. PB1-F2 expression induced an increase in the number and level of expression of activated genes linked to cell death, inflammatory response and neutrophil chemotaxis. When generating interactive gene networks specific to PB1-F2, we identified IFN-γ as a central regulator of PB1-F2-regulated genes. The enhanced cell death of airway-recruited leukocytes was evidenced using an apoptosis assay, confirming the pro-apoptotic properties of PB1-F2. Using a NF-kB luciferase adenoviral vector, we were able to quantify in vivo the implication of NF-kB in the inflammation mediated by the influenza virus infection; we found that PB1-F2 expression intensifies the NF-kB activity. Finally, we quantified the neutrophil recruitment within the airways, and showed that this type of leukocyte is more abundant during the infection of the wild-type virus. Collectively, these data demonstrate that PB1-F2 strongly influences the early host response during IAV infection and provides new insights into the mechanisms by which PB1-F2 mediates virulence

Bacteria isolated from lung modulate asthma susceptibility in mice

Asthma is a chronic, non-curable, multifactorial disease with increasing incidence in industrial countries. This study evaluates the direct contribution of lung microbial components in allergic asthma in mice. Germ-Free and Specific-Pathogen-Free mice display similar susceptibilities to House Dust Mice-induced allergic asthma, indicating that the absence of bacteria confers no protection or increased risk to aeroallergens. In early life, allergic asthma changes the pattern of lung microbiota, and lung bacteria reciprocally modulate aeroallergen responsiveness. Primo-colonizing cultivable strains were screened for their immunoregulatory properties following their isolation from neonatal lungs. Intranasal inoculation of lung bacteria influenced the outcome of allergic asthma development: the strain CNCM I 4970 exacerbated some asthma features whereas the pro-Th1 strain CNCM I 4969 had protective effects. Thus, we confirm that appropriate bacterial lung stimuli during early life are critical for susceptibility to allergic asthma in young adults

Immunomodulation de la sensibilité néonatale au VRS par des bactéries primo-colonisatrices du poumon

National audienc

Caractérisation de la muqueuse pulmonaire et des réponses immunitaires innées associées à l'infection au début de la vie par le Virus Respiratoire Syncytial

Respiratory syncytial virus (RSV) is the main etiologic agent of bovine bronchopneumonia (bovine RSV) and infant bronchiolitis (human RSV). RSV infection can cause severe lower respiratory tract disease in infants, unlike in adults where it is usually asymptomatic and confined to the upper respiratory tract.The infant susceptibility to RSV infection is intrinsically linked to the physiological, immunological and microbiological characteristics of the lung mucosa during the perinatal period. Mucosal immunity and pulmonary microbiota in the perinatal period are players in animal health that are not yet well documented in the literature.Understanding these characteristics of the neonatal lung and the external factors that regulate them could pave the way for new prophylactic strategies.Therefore, I have developed research projects aimed at describing the immunological characteristics and influence of the lung microbiota in the perinatal period to understand the pathophysiological mechanisms triggered by RSV infection in young people and to propose immuno-intervention strategies to modulate the immune response to RSV.Le vírus respiratoire syncytial (VRS) est l’agent étiologique principal des broncho-pneumonies bovines (VRS bovin) et des bronchiolites du nourrisson (VRS humain). L’infection VRS peut provoquer des atteintes sévères des voies respiratoires inférieures chez les jeunes, contrairement à l’adulte où elles sont généralement asymptomatiques et cantonnées aux voies respiratoires supérieures.La sensibilité du nourrisson à une infection VRS est intrinsèquement liée aux caractéristiques physiologiques, immunologiques et microbiologiques de la muqueuse pulmonaire en période périnatale.L’immunité mucosale et le microbiote des poumonsen période périnatale sont des acteurs de la santé animale encore peu détaillés dans la littérature.La compréhension de ces caractéristiques des poumons des nouveau-nés et des facteurs externes qui les régulent pourrait ouvrir la voie à de nouvelles stratégies prophylactiques en faveur de la santé des jeunes. Aussi, j’ai développé des projets de receherche qui visent à décrire les caractéristiques immunologiques et l’influence du microbiote pulmonaires en période périnatale pour comprendre les mécanismes physiopathologiques déclenchés lors de l’infection du jeune par le VRS afin de proposer des stratégies d’immuno-intervention pour moduler la réponse immunitaire anti-VRS

Caractérisation de la muqueuse pulmonaire et des réponses immunitaires innées associées à l'infection au début de la vie par le Virus Respiratoire Syncytial

Respiratory syncytial virus (RSV) is the main etiologic agent of bovine bronchopneumonia (bovine RSV) and infant bronchiolitis (human RSV). RSV infection can cause severe lower respiratory tract disease in infants, unlike in adults where it is usually asymptomatic and confined to the upper respiratory tract.The infant susceptibility to RSV infection is intrinsically linked to the physiological, immunological and microbiological characteristics of the lung mucosa during the perinatal period. Mucosal immunity and pulmonary microbiota in the perinatal period are players in animal health that are not yet well documented in the literature.Understanding these characteristics of the neonatal lung and the external factors that regulate them could pave the way for new prophylactic strategies.Therefore, I have developed research projects aimed at describing the immunological characteristics and influence of the lung microbiota in the perinatal period to understand the pathophysiological mechanisms triggered by RSV infection in young people and to propose immuno-intervention strategies to modulate the immune response to RSV.Le vírus respiratoire syncytial (VRS) est l’agent étiologique principal des broncho-pneumonies bovines (VRS bovin) et des bronchiolites du nourrisson (VRS humain). L’infection VRS peut provoquer des atteintes sévères des voies respiratoires inférieures chez les jeunes, contrairement à l’adulte où elles sont généralement asymptomatiques et cantonnées aux voies respiratoires supérieures.La sensibilité du nourrisson à une infection VRS est intrinsèquement liée aux caractéristiques physiologiques, immunologiques et microbiologiques de la muqueuse pulmonaire en période périnatale.L’immunité mucosale et le microbiote des poumonsen période périnatale sont des acteurs de la santé animale encore peu détaillés dans la littérature.La compréhension de ces caractéristiques des poumons des nouveau-nés et des facteurs externes qui les régulent pourrait ouvrir la voie à de nouvelles stratégies prophylactiques en faveur de la santé des jeunes. Aussi, j’ai développé des projets de receherche qui visent à décrire les caractéristiques immunologiques et l’influence du microbiote pulmonaires en période périnatale pour comprendre les mécanismes physiopathologiques déclenchés lors de l’infection du jeune par le VRS afin de proposer des stratégies d’immuno-intervention pour moduler la réponse immunitaire anti-VRS

La muqueuse pulmonaire chez le nouveau-né : un environnement particulier à comprendre pour prévenir des bonchiolites au VRS

National audienc

Signatures cytokiniques innées et compétence immunitaire chez le veau

National audienc

Detection of influenza viruses by Toll-like receptors: major interactions in the control of responses to flu shots

National audienc