Toward a Scalable Purification Protocol of GaLV-TR-Pseudotyped Lentiviral Vectors

International audienceLentiviral vectors (LV) that are used in research and development as well as in clinical trials are in majority vesicular stomatitis virus G glycoprotein (VSVg) pseudotyped. The predominance of this pseudotype choice for clinical gene therapy studies is largely due to a lack of purification schemes for pseudotypes other than VSVg. In this study, we report for the first time the development of a new downstream process protocol allowing high-yield production of stable and infectious gibbon ape leukemia virus (GaLV)-TR-LV particles. We identified critical conditions in tangential flow filtration (TFF) and chromatographic steps for preserving the infectivity/functionality of LV during purification. This was carried out by identifying for each step, the critical parameters affecting LV infectivity, including pH, salinity, presence of stabilizers, temperature, and by defining the optimal order of these steps. A three-step process was developed for GaLV-TR-LV purification consisting of one TFF and two chromatographic steps (ion-exchange chromatography and size exclusion chromatography) permitting recoveries of >27% of infectious particles. With this process, purified GaLV-pseudotyped LV enabled the transduction of 70% human CD34(+) cells in the presence of the Vectofusin-1 peptide, whereas in the same conditions nonpurified vector transduced only 9% of the cells (multiplicity of infection 20). Our protocol will allow for the first time the purification of GaLV-TR-LV that are biologically active, stable, and with sufficient recovery in the perspective of preclinical studies and clinical applications. Obviously, further optimizations are required to improve final vector yields

JANNUS: A multi-irradiation platform for experimental validation at the scale of the atomistic modelling

International audienceThe joint Accelerators for Nanosciences and NUclear Simulation project was started in 2002 in the frame of collaboration between CEA and CNRS. Due to the scientific skills developed for a long time, two experimental sites have been considered: (1) at Saclay, three electrostatic accelerators are being coupled, a new 3 MV Pelletron machine equipped with a multi-charged ion source, a 2.5 MV single ended Van de Graaff and a 2.25 MV tandem and (2) at Orsay, a 2 MV tandem and a 190 kV ion implanter are being coupled together with a 200 kV transmission electron microscope to allow simultaneous co-irradiation and observation. A brief review is first presented on multi-irradiation facilities available in the world. Then, a technical description of the new experimental facilities being installed is given. The main experiments we intend to carry out using mono, dual or triple irradiation configurations in different nuclear application fields and especially in the fusion domain will be further presented. (C) 2009 Elsevier B.V. All rights reserved

JANNUS: experimental validation at the scale of atomic modelling

Ion irradiation is well suited to simulate neutron irradiation because primary knock-on atoms (PKA) produced by neutron collisions are self ions of the target. As the main difference, the energy spectrum of ion-produced PKAs is somewhat broader than in the case of fast neutrons. Studies of the combined effects of target damaging, ion implantation effects, helium and hydrogen production, and the occurrence of nuclear reactions should be performed by co-irradiation experiments (dual or triple beam irradiation). The JANNUS project (Joint Accelerators for Nanosciences and NUclear Simulation) was started in 2002 in the frame of a collaboration between CEA (Commissariat a l'Energie Atomique) and CNRS-IN2P3 (Centre National de la Recherche Scientifique-Institut National de Physique Nucleaire et de Physique des Particules). Two experimental sites are involved. At Saclay, three electrostatic accelerators are being coupled: a new 3 MV Pelletron (TM) machine equipped with an ECR multi-charged ion source, a 2.5 MV single ended Van de Graaff and a 2.25 MV General Ionex tandem. At Orsay, the 2 MV tandem ARAMIS and the 190 kV ion implanter IRMA are being coupled with a 200 kV TECNAI (TM) transmission electron microscope to allow simultaneous co-irradiation and observation. This paper will first discuss both advantages and limitations of the use of ion beam irradiation to simulate neutron irradiation. A technical description of both set-ups is then presented, and some details will be given concerning multi-irradiation facilities running worldwide. The main application fields of JANNUS will be further detailed

Influence of ball-milling and annealing conditions on nanocluster characteristics in oxide dispersion strengthened steels

International audienc

Influence of ball-milling and annealing conditions on nanocluster characteristics in oxide dispersion strengthened steels

International audienc

Chemical reactivity and ion beam irradiation behaviour of perovskite- and zirconolite-nuclear ceramics type

International audienceOxide ceramics of two neighboring families: perovskite A(II)B(IV)O-3 and zirconolite A(II)B(IV)C(IV)(2)O-7 have been synthesized by a classical solid route. Substitution of divalent cation (Ca) by trivalent cation (Nd) was tested on zirconolite compositions. Then, the ceramic pellets were submitted to aqueous leaching tests at 90 degrees C in deionized water. Some of them were previously ion irradiated with 150 keV Xe+ within a fluence range 5 x 10(13)-1 x 10(15) cm(-2) in order to study the effect of ion damaging on their intrinsic chemical reactivity. X-ray diffraction (XRD), electron microprobe analysis (EMA), scanning electron microscopy (SEM) and ion beam analysis (IBA) methods were used to characterize the evolution of the crystallinity level and the surface chemical composition of the ceramics after each step (synthesis, irradiation, leaching). The alteration mechanism of unirradiated titanate ceramics appears to be not uniform at the sample surface. Chemical durability of zirconolite is shown to be dependent both on the pH of the aqueous solution and the ceramic composition. Surface hydration only concerns a very thin layer, typically 200 nm and the hydrogen content does not go beyond 1-2 at.%. No differences have been detected in the leaching behaviour of unirradiated or irradiated perovskite samples. (c) 2006 Elsevier B.V. All rights reserved