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

Minerva (MYRRHA Phase 1) RFQ Beam Commissioning

International audienceThe MYRRHA project aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. Phase 1 of the project will realize a 100 MeV, 4 mA superconducting linac with the mission of ensuring the ADS requirements in terms of reliability and fault tolerance. As part of the reliability optimization program the integrated prototyping of the MINERVA injector is ongoing. The front-end of the injector is composed of an ECR proton source, a 2.6 m long LEBT (low energy beam transport line) and a four-rod RFQ accelerating the beam to 1.5 MeV. The present contribution focuses on the current beam tests on the RFQ, including beam matching, RF conditioning, assessment of the cavities’ performances and accelerated beam characterisation

MYRRHA-MINERVA Injector Status and Commissioning

International audienceThe MYRRHA project at SCK•CEN, Belgium, aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. MYRRHA’s linac is designed to be fault tolerant thanks to redundancy implemented in parallel at low energy and serially in the superconducting linac. Phase 1 of the project, named MINERVA, will realise a 100 MeV, 4 mA superconducting linac with the mission of demonstrating the ADS requirements in terms of reliability and of fault tolerance. As part of the reliability optimisation program the integrated prototyping of the MINERVA injector is ongoing at SCK•CEN in Louvain-la-Neuve, Belgium. The injector test stand aims at testing sequentially all the elements composing the front-end of the injector. This contribution will highlight the beam dynamics choices in MINERVA’s injector and their impact on ongoing commissioning activities

Individual rotavirus-like particles containing 120 molecules of fluorescent protein are visible in living cells

39 ref.International audienceRotaviruses are large, complex icosahedral particles consisting of three concentric capsid layers. When the innermost capsid protein VP2 is expressed in the baculovirus-insect cell system it assembles as core-like particles. The amino terminus region of VP2 is dispensable for assembly of virus-like particles (VLP). Coexpression of VP2 and VP6 produces double layered VLP. We hypothesized that the amino end of VP2 could be extended without altering the auto assembly properties of VP2. Using the green fluorescent protein (GFP) or the DsRed protein as model inserts we have shown that the chimeric protein GFP (or DsRed)-VP2 auto assembles perfectly well and forms fluorescent VLP (GFP-VLP2/6 or DsRed-VLP2/6) when coexpressed with VP6. The presence of GFP inside the core does not prevent the assembly of the outer capsid layer proteins VP7 and VP4 to give VLP2/6/7/4. Cryo-electron microscopy of purified GFP-VLP2/6 showed that GFP molecules are located at the 5-fold vertices of the core. It is possible to visualize a single fluorescent VLP in living cells by confocal fluorescent microscopy. In vitro VLP2/6 did not enter into permissive cells or in dendritic cells. In contrast, fluorescent VLP2/6/7/4 entered the cells and then the fluorescence signal disappear rapidly. Presented data indicate that fluorescent VLP are interesting tools to follow in real time the entry process of rotavirus and that chimeric VLP could be envisaged as “nanoboxes” carrying macromolecules to living cells

Virus-like particles as a vaccine delivery system: myths and facts.

Vaccines against viral disease have traditionally relied on attenuated virus strains or inactivation of infectious virus. Subunit vaccines based on viral proteins expressed in heterologous systems have been effective for some pathogens, but have often suffered from poor immunogenicity due to incorrect protein folding or modification. In this chapter we focus on a specific class of viral subunit vaccine that mimics the overall structure of virus particles and thus preserves the native antigenic conformation of the immunogenic proteins. These virus-like particles (VLPs) have been produced for a wide range of taxonomically and structurally distinct viruses, and have unique advantages in terms of safety and immunogenicity over previous approaches. With new VLP vaccines for papillomavirus beginning to reach the market place we argue that this technology has now 'come-of-age' and must be considered a viable vaccine strategy