The cytoplasmic tail of the rabies virus G protein is an essential domain controlling death/survival in human neuronal cells

Poster presentation

In vitro and in vivo evaluation of a single chain antibody fragment generated in planta with potent rabies neutralisation activity.

Rabies causes more than 60,000 human deaths annually in areas where the virus is endemic. Importantly, rabies is one of the few pathogens for which there is no treatment following the onset of clinical disease with the outcome of infection being death in almost 100% of cases. Whilst vaccination, and the combination of vaccine and rabies immunoglobulin treatment for post-exposure administration are available, no tools have been identified that can reduce or prevent rabies virus replication once clinical disease has initiated. The search for effective antiviral molecules to treat those that have already developed clinical disease associated with rabies virus infection is considered one of the most important goals in rabies research. The current study assesses a single chain antibody molecule (ScFv) based on a monoclonal antibody that potently neutralises rabies in vitro as a potential therapeutic candidate. The recombinant ScFv was generated in Nicotiana benthamiana by transient expression, and was chemically conjugated (ScFv/RVG) to a 29 amino acid peptide, specific for nicotinic acetylcholine receptor (nAchR) binding in the CNS. This conjugated molecule was able to bind nAchR in vitro and enter neuronal cells more efficiently than ScFv. The ability of the ScFv/RVG to neutralise virus in vivo was assessed using a staggered administration where the molecule was inoculated either four hours before, two days after or four days after infection. The ScFv/RVG conjugate was evaluated in direct comparison with HRIG and a potential antiviral molecule, Favipiravir (also known as T-705) to indicate whether there was greater bioavailability of the ScFv in the brains of treated mice. The study indicated that the approach taken with the ScFv/RVG conjugate may have utility in the design and implementation of novel tools targetting rabies virus infection in the brain

Toll-Like Receptor 3 (TLR3) Plays a Major Role in the Formation of Rabies Virus Negri Bodies

Human neurons express the innate immune response receptor, Toll-like receptor 3 (TLR3). TLR3 levels are increased in pathological conditions such as brain virus infection. Here, we further investigated the production, cellular localisation, and function of neuronal TLR3 during neuronotropic rabies virus (RABV) infection in human neuronal cells. Following RABV infection, TLR3 is not only present in endosomes, as observed in the absence of infection, but also in detergent-resistant perinuclear inclusion bodies. As well as TLR3, these inclusion bodies contain the viral genome and viral proteins (N and P, but not G). The size and composition of inclusion bodies and the absence of a surrounding membrane, as shown by electron microscopy, suggest they correspond to the previously described Negri Bodies (NBs). NBs are not formed in the absence of TLR3, and TLR3−/− mice—in which brain tissue was less severely infected—had a better survival rate than WT mice. These observations demonstrate that TLR3 is a major molecule involved in the spatial arrangement of RABV–induced NBs and viral replication. This study shows how viruses can exploit cellular proteins and compartmentalisation for their own benefit

Etude genetique et moleculaire de la glycoproteine du virus rabique CVS

CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Role of the glycoprotein thorns in anxious effects of rabies virus: Evidence from an animal study

International audienceRabies is a lethal infectious disease caused by rabies virus (RABV). Fear and anxiety are the distinguished symptoms in rabies patients. Fusion of RABV envelope glycoprotein (RVG) to host cell membrane initiates rabies pathogenesis via interacting with PDZ domain of signaling proteins. We assessed the anxiety-like behaviors, and hypothalamic-pituitary-adrenal axis (HPA) response to RVG infection. Contribution of PDZ binding motif (PBM) of RVG to the observed effects was also examined using a mutant form of RVG, ΔRVG, with deleted last four amino acids at PBM C-terminus. Lentiviral vectors containing RVG and/or ΔRVG genes were injected into the rat brain areas involved in anxiety including hypothalamus, dorsal hippocampus, and amygdala. RVG/ΔRVG neural expression was examined by fluorescent microscopy. Anxiety-like behaviors were assessed by elevated plus maze (EPM) and open field (OF) tasks. HPA response was evaluated via measuring corticosterone serum level by ELISA technique. RVG/ΔRVG were successfully expressed in neurons of the injected areas. RVG, but not ΔRVG, infection of hypothalamus and amygdala increased the time spent in EPM open arms, and OF total distance moved and velocity. RVG, but not ΔRVG, infection of hypothalamus and dorsal hippocampus increased corticosterone level. The anxiety-like behaviors and exploratory/locomotor activities of rats with RVG infection in hypothalamus, and amygdala are mediated by PBM of RVG. The HPA response to RVG infection of hypothalamus and dorsal hippocampus is dependent to PBM of RVG. Triggering anxiety-related signaling by PBM of RVG seems to be one of the mechanisms involved in anxiety behaviors seen in patients with rabies

Investigation of rabies virus glycoprotein carboxyl terminus as an in vitro predictive tool of neurovirulence. A 3R approach.

International audienceIn the field of live viral vaccines production, there is an unmet need for in vitro tests complying a 3R approach (Refine, Replace and Reduce the use of animal experimentation) to replace the post-licensing safety tests currently assayed in animals. Here, we performed a pilot study evaluating whether virulence of rabies virus, RABV, can be forecast by an in vitro test of neurite outgrowth. The rationale to use neurite outgrowth as a read-out for this test is based on the salient property of the cytoplasmic domain of the G-protein (Cyto-G) of virulent RABV strains - not of attenuated RABV strains - to stimulate neurite outgrowth in vitro. We observed that neurite elongation triggered by the Cyto-Gs encoded by different RABV field isolates correlate with the distinct virulence scores obtained in a mouse model of experimental rabies. Our results cast the idea that it could be feasible to predict RABV virulence by testing the in vitro property of a RABV strain to promote neurite outgrowth without the use of animal experimentation

1H, 13C and 15N resonance assignments of the PDZ of microtubule-associated serine/threonine kinase 205 (MAST205) in complex with the C-terminal motif from the rabies virus glycoprotein.

International audienceMost of microbes hijack the cellular machinery to their advantage by interacting with specific target of the host cell. Glycoprotein of rabies virus is a key factor controlling the homeostasis of infected neuronal cells and proteins belonging to the human microtubule associated serine threonine kinase family have been identified as potential cellular partners. As a first step towards its structural study, we have assigned the backbone and side chain nuclei resonances of the PDZ domain (PSD-95, Discs Large, ZO-1) of MAST205 in complex with the C-terminal residues of the glycoprotein of rabies virus. The BMRB accession code is 155972

Comparison of G protein sequences of South African street rabies viruses showing distinct progression of the disease in a mouse model of experimental rabies

International audienceRabies is a fatal zoonotic disease and infections generally lead to a fatal encephalomyelitis in both humans and animals. In South Africa, domestic (dogs) and the wildlife (yellow mongoose) host species maintain the canid and mongoose rabies variants respectively. In this study, pathogenicity differences of South African canid and mongoose rabies viruses were investigated in a murine model, by assessing the progression of clinical signs and survivorship. Comparison of glycoprotein gene sequences revealed amino acid differences that may underpin the observed pathogenicity differences. Cumulatively, our results suggest that the canid rabies virus may be more neurovirulent in mice than the mongoose rabies variant

Recombinant Nucleoprotein-Based Enzyme-Linked Immunosorbent Assay for Detection of Immunoglobulin G Antibodies to Crimean-Congo Hemorrhagic Fever Virus

The full-length nucleoprotein of Crimean-Congo hemorrhagic fever virus (CCHFV; 482 amino acid residues) was expressed as a His-tagged recombinant protein (His-CCHFV rNP) in the baculovirus system. The His-CCHFV rNP was efficiently expressed in insect cells and purified by Ni(2+) column chromatography. Using this substrate, an immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) was developed. We evaluated the sensitivity and specificity of the IgG ELISA, using serum samples previously determined to be antibody positive or negative by immunofluorescence tests on CCHFV-infected Vero E6 cells. We found very good correlation between the two tests: 87% for the positive sera (13 of 15) and 99% for the negative sera (107 of 108). These results indicate that the new IgG ELISA using His-CCHFV rNP has high sensitivity and specificity for detecting CCHFV antibodies. The CCHF patients' sera with high titers reacted only with the NP fragment containing amino acid residues between 201 and 306 in Western blotting. It is known that amino acid homologies are high in this region among various isolates. Thus, it is expected that this ELISA can detect antibodies not only for Chinese strains of CCHFV but also for other strains circulating in the world. These results suggest that the IgG ELISA system developed with the recombinant CCHFV NP is a valuable tool for diagnosis and epidemiological investigations of CCHFV infections