Transcriptomic analysis of neonatal vs. adult lung early responses to RSV reveals key roles for DC and type I IFN in controlling immunopathologic imprinting

International audienc

Neonatal Nasal Vaccination with the Nucleoprotein of the Respiratory Syncytial Virus Elicits Virus-protective but Airway-pathogenic Th2-biased Immunity that can be Modulated by the Choice of Adjuvants

There is still no licensed vaccine against human respiratory syncytial virus (RSV) which causes severe bronchiolitis in yound children. The nucleoprotein N, a major component of the RSV nucleocapsid, is remarkably conserved among RSV subtypes and is recognized as a target of protective T cell responses. We reported a method to produce recombinant N assembling in homogenous rings composed of 10-11 N subunits.Intranasal vaccination of adult BALB/c mice with N-rings and detoxified E.coli enterotoxin LT(R192G) as adjuvant (provided by J. Clements, USA), proved protective against an RSV challenge, without causing significant lung inflammatory reactions. In the present study, we evaluated the vaccine potential of N-rings in 5 to 7 day-old BALB/c pups: a single intranasal administration of N-rings with LT(R192G) provided a significant reduction of the viral load after an RSV challenge at five weeks of age. However, neonatal vaccination also generated an enhanced lung infiltration by eosinophils following the RSV challenge. Analysis of antibody subclasses and cytokines produced after an RSV challenge or a boost administration of the vaccine suggested that neonatal vaccination induced a long lasting Th2 biased local immune memory. This early Th2 bias could be prevented by adding CpG-ODN to the vaccine formulation, but then the protection against virus replication was also reduced. In conclusion, protective vaccination against RSV can be achieve in neonates but requires an appropriate combinations of adjuvant

A Novel Subnucleocapsid Nanoplatform for Mucosal Vaccination against Influenza Virus That Targets the Ectodomain of Matrix Protein 2

International audienceIn this study, subnucleocapsid nanorings formed by the recombinant nucleoprotein (N) of the respiratory syncytial virus were evaluated as a platform to anchor heterologous antigens. The ectodomain of the influenza virus A matrix protein 2 (M2e) is highly conserved and elicits protective antibodies when it is linked to an immunogenic carrier, making it a promising target to develop universal influenza vaccines. In this context, one or three M2e copies were genetically linked to the C terminus of N to produce N-M2e and N-3M2e chimeric recombinant nanorings. Mice were immunized intranasally with N-M2e or N-3M2e or with M2e or 3M2e control peptides. N-3M2e-vaccinated mice showed the strongest mucosal and systemic antibody responses. These mice presented a reduced viral load and minor weight loss, and all survived upon challenge with influenza virus A/PR8/34 (H1N1) (PR8). We compared the intranasal route to the subcutaneous route of N-3M2e immunization. Only the intranasal route induced a strong local IgA response and led to the protection of mice upon challenge. Finally, we demonstrated that the induction of anti-M2e antibodies by N-3M2e is not impaired by preexisting anti-N immunity. Overall, these results show that the N nanoring is a potent carrier for mucosal delivery of vaccinal antigens

A novel proteic nano-platform for antigens: application to musocal influenza vaccination.

absen

Lung neonatal responses to respiratory syncytial virus reveal deficiencies in dendritic cells and type I interferon in a mouse model of airway enhanced disease

International audienc

Flt3 ligand improves the innate response to respiratory syncytial virus and limits lung disease upon RSV reexposure in neonate mice

Respiratory syncytial virus (RSV) causes severe bronchiolitis in infants worldwide. The immunological factors responsible for RSV susceptibility in infants are poorly understood. Here, we used the BALB/c mouse model of neonatal RSV infection to study the mechanisms leading to severe disease upon reexposure to the virus when adults. Two major deficiencies in neonatal lung innate responses were found: a poor DCs mobilization, and a weak engagement of the IFNI pathway. The administration of Flt3 ligand (Flt3-L), a growth factor that stimulates the proliferation of hematopoietic cells, to neonates before RSV-infection, resulted in increased lung DC number, and reconditioned the IFNI pathway upon RSV neonatal infection. Besides, neonates treated with Flt3-L were protected against exacerbated airway disease upon adult reexposure to RSV. This was associated with a reorientation of RSV-specific responses toward Th1-mediated immunity. Thus, the poor lung DCs and IFNI responses to RSV in neonates may be partly responsible for the deleterious long-term consequences revealed upon adult reexposure to RSV, which could be prevented by Flt3-L treatment. These results open new perspectives for developing neonatal immuno-modulating strategies to reduce the burden of bronchiolitis

Age-related differences in the lung tissue susceptibility to Respiratory Syncytial Virus

International audienceThe high incidence of acute lower respiratory tract infections (ALRI) in infants likely relates to the immaturity of the neonatal pulmonary immune system. Respiratory syncytial virus (RSV), a paramyxovirus, is the most frequently encountered virus in severe ALRI, during early infancy. The immune mechanisms associated with this higher susceptibility are still largely unknown. Our objective was to assess age-related differences in the lung susceptibility to RSV in lambs as a model for the veterinary (calves) and human pathology: lambs are susceptible to bovine RSV, and preterm lambs develop more severe ALRI, just like preterm infants. Besides lamb is a widely-used model for studies concerning respiratory deficiencies of preterm infants, as infant and lamb have a similar pulmonary development. We collected samples of tracheal, lung and mediastinal lymph node tissue from either preterm lambs or from 1 week to 9 month-old lambs. We first looked at Toll-Like Receptors (TLR) and Protease-Activated Receptors (PAR) mRNA expression, as early mediators of inflammation and antiviral defenses. Depending on the tissue, we found differential mRNA expression for both PAR and TLR, whereas age variations were mainly observed for TLR3, 7 and 9 expressions. Because TLR are mostly expressed by dendritic cells (DC), we next characterized conventional DC subsets in the lung by FACS according to age. Thus, we demonstrated age-related differences on major receptors involved in antiviral defenses. To prove that it contributes to newborn susceptibility to RSV, we are now developing a model of lung explants culture to analyze gene expression during RSV infection

Evaluation dans l'espèce cible d'une nouvelle stratégie vaccinale contre le virus respiratoire syncytial bovin, basée sur des assemblages nanoparticulaires de la protéine de nucléocapside

National audienc

Evaluation dans l'espèce cible d'une nouvelle stratégie vaccinale contre le virus respiratoire syncytial bovin, basée sur des assemblages nanoparticulaires de la protéine de nucléocapside

National audienc