Biology subjects

Moureau, G.

Publications and source records attributed to Moureau, G..

6 recordsLinked to original sources

bioRxiv2024

In vivo rescue of arboviruses directly from subgenomic DNA fragments

Reverse genetic systems are mainly used to study RNA viruses and rescue recombinant strains in cell culture. Here, we provide proof-of-concept for direct in vivo viral generation using the Infectious Subgenomic Amplicons method. So far, this procedure allowed to rescue in vitro RNA viruses, by the transfection of several overlapping subgenomic DNA fragments encoding the entire virus genome. We adapted and optimized this technique to generate a pathogenic tick-borne encephalitis virus strain in mice. To define optimal protocol parameters, we injected intramuscularly different amounts of DNA fragments associated, or not, to electroporation. The injection of only 1{micro}g of DNA fragments combined with electroporation resulted in an infection rate of 100%. Then, these parameters were applied to rescue another flavivirus and an alphavirus. This method provides a novel and efficient strategy for in vivo viral generation, which is typically achieved by injecting infectious clones. Furthermore, as part of the development of DNA- launched live attenuated vaccines, this approach, which also has the advantage of not injecting vector DNA, may simplify the generation of attenuated strains in vivo.

microbiology↗

bioRxiv2021

Pre-clinical evaluation of antiviral activity of nitazoxanide against Sars-CoV-2

To address the emergence of SARS-CoV-2, multiple clinical trials in humans were rapidly started, including those involving an oral treatment by nitazoxanide, despite no or limited pre-clinical evidence of antiviral efficacy. In this work, we present a complete pre-clinical evaluation of the antiviral activity of nitazoxanide against SARS-CoV-2. First, we confirmed the in vitro efficacy of nitazoxanide and tizoxanide (its active metabolite) against SARS-CoV-2. Then, we demonstrated nitazoxanide activity in a reconstructed bronchial human airway epithelium model. In a SARS-CoV-2 virus challenge model in hamsters, oral and intranasal treatment with nitazoxanide failed to impair viral replication in commonly affected organs. We hypothesized that this could be due to insufficient diffusion of the drug into organs of interest. Indeed, our pharmacokinetic study confirmed that concentrations of tizoxanide in organs of interest were always below the in vitro EC50. These preclinical results suggest, if directly applicable to humans, that the standard formulation and dosage of nitazoxanide is not effective in providing antiviral therapy for Covid-19.

pathology↗

bioRxiv2021

SARS-CoV-2 20I/501Y.V1 variant in the hamster model

Late 2020, SARS-CoV-2 Alpha variant from lineage B.1.1.7 emerged in United Kingdom and gradually replaced the G614 strains initially involved in the global spread of the pandemic. In this study, we used a Syrian hamster model to compare a clinical strain of Alpha variant with an ancestral G614 strain. The Alpha variant succeeded to infect animals and to induce a pathology that mimics COVID-19. However, both strains replicated to almost the same level and induced a comparable disease and immune response. A slight fitness advantage was noted for the G614 strain during competition and transmission experiments. These data do not corroborate the epidemiological situation observed during the first half of 2021 in humans nor reports that showed a more rapid replication of Alpha variant in human reconstituted bronchial epithelium.

microbiology↗

bioRxiv2020

Preclinical evaluation of Imatinib does not support its use as an antiviral drug against SARS-CoV-2

Following the emergence of SARS-CoV-2, the search for an effective and rapidly available treatment was initiated worldwide based on repurposing of available drugs. Previous reports described the antiviral activity of certain tyrosine kinase inhibitors (TKIs) targeting the Abelson kinase 2 against pathogenic coronaviruses. Imatinib, one of them, has more than twenty years of safe utilization for the treatment of hematological malignancies. In this context, Imatinib was rapidly evaluated in clinical trials against Covid-19. Here, we present the pre-clinical evaluation of Imatinib in multiple models. Our results indicated that Imatinib and another TKI, the Masitinib, exhibit an antiviral activity in VeroE6 cells. However, Imatinib was inactive in a reconstructed bronchial human airway epithelium model. In vivo, Imatinib therapy failed to impair SARS-CoV-2 replication in a golden Syrian hamster model despite high concentrations in plasma and in the lung. Overall, these results do not support the use of Imatinib and similar TKIs as antivirals in the treatment of Covid-19.

microbiology↗

bioRxiv2020

Favipiravir and severe acute respiratory syndrome coronavirus 2 in hamster model

Despite no or limited pre-clinical evidence, repurposed drugs are massively evaluated in clinical trials to palliate the lack of antiviral molecules against SARS-CoV-2. Here we used a Syrian hamster model to assess the antiviral efficacy of favipiravir, understand its mechanism of action and determine its pharmacokinetics. When treatment was initiated before or simultaneously to infection, favipiravir had a strong dose effect, leading to dramatic reduction of infectious titers in lungs and clinical alleviation of the disease. Antiviral effect of favipiravir correlated with incorporation of a large number of mutations into viral genomes and decrease of viral infectivity. The antiviral efficacy observed in this study was achieved with plasma drug exposure comparable with those previously found during human clinical trials and was associated with weight losses in animals. Thereby, pharmacokinetic and tolerance studies are required to determine whether similar effects can be safely achieved in humans.

microbiology↗

bioRxiv2018

Exploratory re-encoding of Yellow Fever Virus genome: analysis of in vitro and in vivo replicative phenotypes

Virus attenuation by genome re-encoding is a pioneering approach for generating effective live-attenuated vaccine candidates. Its core principle is to introduce a large number of synonymous substitutions into the viral genome to produce stable attenuation of the targeted virus. Introduction of large numbers of mutations has also been shown to maintain stability of the attenuated phenotype by lowering the risk of reversion and recombination of re-encoded genomes. Identifying mutations with low fitness cost is pivotal as this increases the number that can be introduced and generates more stable and attenuated viruses. Here, we sought to identify mutations with low deleterious impact on the in vivo replication and virulence of yellow fever virus (YFV). Following comparative bioinformatic analyses of flaviviral genomes, we categorized synonymous transition mutations according to their impact on CpG/UpA composition and secondary RNA structures. We then designed 17 re-encoded viruses with 100-400 synonymous mutations in the NS2A-to-NS4B coding region of YFV Asibi and Ap7M (hamster-adapted) genomes. Each virus contained a panel of synonymous mutations designed according to the above categorisation criteria. The replication and fitness characteristics of parent and re-encoded viruses were compared in vitro using cell culture competition experiments. In vivo laboratory hamster models were also used to compare relative virulence and immunogenicity characteristics. Most of the re-encoded strains showed no decrease in replicative fitness in vitro. However, they showed reduced virulence and, in some instances, decreased replicative fitness in vivo. Importantly, the most attenuated of the re-encoded strains induced robust, protective immunity in hamsters following challenge with Ap7M, a virulent virus. Overall, the introduction of transitions with no or a marginal increase in the number of CpG/UpA dinucleotides had the mildest impact on YFV replication and virulence in vivo. Thus, this strategy can be incorporated in procedures for the finely tuned creation of substantially re-encoded viral genomes.

microbiology↗