Utilisation des primates non humains en recherche biomédicale

Les similitudes génétiques, anatomiques et physiologiques qui existent entre l'homme et les primates non humains font de ces animaux des modèles très précieux en recherche biomédicale. Après avoir présenté les différents domaines d'utilisation des primates non humains en recherche biomédicale, l'auteur s'est attaché à effectuer un bilan de l'ensemble des connaissances " pratiques " qu'il a jugé nécessaire d'avoir lors d'utilisation de primates non humains à des fins scientifiques : les contraintes réglementaires et éthiques, les conditions de maintenance en laboratoire, les risques sanitaires liés à la manipulation de ces animaux ou encore les conditions d'approvisionnement en primates non humains en France

Chikungunya Virus Neutralization Antigens and Direct Cell-to-Cell Transmission Are Revealed by Human Antibody-Escape Mutants

Chikungunya virus (CHIKV) is an alphavirus responsible for numerous epidemics throughout Africa and Asia, causing infectious arthritis and reportedly linked with fatal infections in newborns and elderly. Previous studies in animal models indicate that humoral immunity can protect against CHIKV infection, but despite the potential efficacy of B-cell-driven intervention strategies, there are no virus-specific vaccines or therapies currently available. In addition, CHIKV has been reported to elicit long-lasting virus-specific IgM in humans, and to establish long-term persistence in non-human primates, suggesting that the virus might evade immune defenses to establish chronic infections in man. However, the mechanisms of immune evasion potentially employed by CHIKV remain uncharacterized. We previously described two human monoclonal antibodies that potently neutralize CHIKV infection. In the current report, we have characterized CHIKV mutants that escape antibody-dependent neutralization to identify the CHIKV E2 domain B and fusion loop “groove” as the primary determinants of CHIKV interaction with these antibodies. Furthermore, for the first time, we have also demonstrated direct CHIKV cell-to-cell transmission, as a mechanism that involves the E2 domain A and that is associated with viral resistance to antibody-dependent neutralization. Identification of CHIKV sub-domains that are associated with human protective immunity, will pave the way for the development of CHIKV-specific sub-domain vaccination strategies. Moreover, the clear demonstration of CHIKV cell-to-cell transmission and its possible role in the establishment of CHIKV persistence, will also inform the development of future anti-viral interventions. These data shed new light on CHIKV-host interactions that will help to combat human CHIKV infection and inform future studies of CHIKV pathogenesis

A Cooperative Interaction between Nontranslated RNA Sequences and NS5A Protein Promotes In Vivo Fitness of a Chimeric Hepatitis C/GB Virus B

GB virus B (GBV-B) is closely related to hepatitis C virus (HCV), infects small non-human primates, and is thus a valuable surrogate for studying HCV. Despite significant differences, the 5′ nontranslated RNAs (NTRs) of these viruses fold into four similar structured domains (I-IV), with domains II-III-IV comprising the viral internal ribosomal entry site (IRES). We previously reported the in vivo rescue of a chimeric GBV-B (vGB/IIIHC) containing HCV sequence in domain III, an essential segment of the IRES. We show here that three mutations identified within the vGB/IIIHC genome (within the 3′NTR, upstream of the poly(U) tract, and NS5A coding sequence) are necessary and sufficient for production of this chimeric virus following intrahepatic inoculation of synthetic RNA in tamarins, and thus apparently compensate for the presence of HCV sequence in domain III. To assess the mechanism(s) underlying these compensatory mutations, and to determine whether 5′NTR subdomains participating in genome replication do so in a virus-specific fashion, we constructed and evaluated a series of chimeric subgenomic GBV-B replicons in which various 5′NTR subdomains were substituted with their HCV homologs. Domains I and II of the GBV-B 5′NTR could not be replaced with HCV sequence, indicating that they contain essential, virus-specific RNA replication elements. In contrast, domain III could be swapped with minimal loss of genome replication capacity in cell culture. The 3′NTR and NS5A mutations required for rescue of the related chimeric virus in vivo had no effect on replication of the subgenomic GBneoD/IIIHC RNA in vitro. The data suggest that in vivo fitness of the domain III chimeric virus is dependent on a cooperative interaction between the 5′NTR, 3′NTR and NS5A at a step in the viral life cycle subsequent to genome replication, most likely during particle assembly. Such a mechanism may be common to all hepaciviruses

Etude des déterminants de la réplication du virus GB-B en culture cellulaire et in vivo (développement d'un modèle d'étude du virus de l'hépatite C)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Utilisation des primates non humains en recherche biomédicale

Les similitudes génétiques, anatomiques et physiologiques qui existent entre l homme et les primates non humains font de ces animaux des modèles très précieux en recherche biomédicale. Après avoir présenté les différents domaines d utilisation des primates non humains en recherche biomédicale, l auteur s est attaché à effectuer un bilan de l ensemble des connaissances pratiques qu il a jugé nécessaire d avoir lors d utilisation de primates non humains à des fins scientifiques : les contraintes réglementaires et éthiques, les conditions de maintenance en laboratoire, les risques sanitaires liés à la manipulation de ces animaux ou encore les conditions d approvisionnement en primates non humains en France.TOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE-EN Vétérinaire (315552301) / SudocSudocFranceF

Protective antibody threshold of RTS,S/AS01 malaria vaccine correlates antigen and adjuvant dose in mouse model

Abstract Mouse models are useful for the early down-selection of malaria vaccine candidates. The Walter Reed Army Institute of Research has optimized a transgenic Plasmodium berghei sporozoite challenge model to compare the efficacy of Plasmodium falciparum circumsporozoite protein (CSP) vaccines. GSK’s RTS,S vaccine formulated in the adjuvant AS01 can protect malaria-naïve individuals against malaria. We report that the RTS,S/AS01 vaccine induces high level sterile protection in our mouse model. Down titration of the antigen at a constant AS01 dose revealed a potent antigen dose-sparing effect and the superiority of RTS,S/AS01 over a soluble CSP antigen. RTS,S-mediated protective immunity was associated with a threshold of major repeat antibody titer. Combined titration of the antigen and adjuvant showed that reducing the adjuvant could improve antibody boosting post-3rd vaccination and reduce the threshold antibody concentration required for protection. Mouse models can provide a pathway for preclinical assessment of strategies to improve CSP vaccines against malaria

Immunogenicity of an AS01-adjuvanted respiratory syncytial virus prefusion F (RSVPreF3) vaccine in animal models

Abstract Respiratory syncytial virus (RSV) causes a high disease burden in older adults. An effective vaccine for this RSV-primed population may need to boost/elicit robust RSV-neutralizing antibody responses and recall/induce RSV-specific T cell responses. To inform the selection of the vaccine formulation for older adults, RSVPreF3 (RSV fusion glycoprotein engineered to maintain the prefusion conformation) with/without AS01 adjuvant was evaluated in mice and bovine RSV infection-primed cattle. In mice, RSVPreF3/AS01 elicited robust RSV-A/B-specific neutralization titers and RSV F-specific polyfunctional CD4+ T cell responses exceeding those induced by non-adjuvanted RSVPreF3. In primed bovines, RSVPreF3/AS01 tended to induce higher pre-/post-vaccination fold-increases in RSV-A/B-specific neutralization titers relative to non-adjuvanted and Alum-adjuvanted RSVPreF3 formulations, and elicited higher RSV F-specific CD4+ T cell frequencies relative to the non-adjuvanted vaccine. Though AS01 adjuvanticity varied by animal species and priming status, RSVPreF3/AS01 elicited/boosted RSV-A/B-specific neutralization titers and RSV F-specific CD4+ T cell responses in both animal models, which supported its further clinical evaluation as prophylactic candidate vaccine for older adults

Translational activities of 3′NTR mutant replicons in cB76.1/Huh7 cells

a<p>Replicon RNAs containing 3′NTR mutations or deletions correspond to those depicted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004419#pone-0004419-g005" target="_blank">Fig. 5A</a>, but encode firefly luciferase (F-Luc) in place of neomycine phosphotransferase. Luc-RepDΔIII and LucD-GAA control RNAs are described in the legend of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004419#pone-0004419-g002" target="_blank">Fig. 2</a>.</p>b<p>F-Luc RLU activities were determined 4 hours after transfection of equal amounts (5 µg) of replicon RNAs into cB76.1/Huh7 cells, and expressed relatively to Luc-RepD set at 100% after normalization with respect to total protein quantities assayed (mean±SD from two independent transfections, each monitored in duplicate wells).</p