Biology subjects

Nevers, Q.

Publications and source records attributed to Nevers, Q..

6 recordsLinked to original sources

bioRxiv2025

Identification and characterization of a non-peptidic cyclophilin ligand with antiviral activity against feline and porcine α-coronaviruses.

Coronaviruses (CoVs) are emerging pathogens that have been extensively studied over the last 20 years and can cause acute respiratory diseases in humans, as exemplified by the SARS-CoV-2 pandemic. Coronaviruses are also known for their importance in veterinary medicine, being responsible for severe pathologies in pets and livestock. These include Feline Infectious Peritonitis Virus (FIPV), which causes a fatal disease in cats. In livestock, porcine coronaviruses such as Transmissible Gastroenteritis Virus (TGEV) and Porcine Epidemic Diarrhoea Virus (PEDV) are the causative agents of an acute enteric disease in piglets with a high mortality rate and a significant impact on the pork industry. In addition, animal coronaviruses may represent a zoonotic reservoir. Therefore, efficient antiviral strategies are required to inhibit the multiplication of coronaviruses infecting various animal species. Here, we synthesized 20 small-molecule ligands that target cyclophilins, a family of cellular chaperons hijacked by several viruses including CoVs. We screened their antiviral activity against feline and porcine alpha-CoVs, and identified a compound, F83233, as a potent inhibitor of FIPV, TGEV and PEDV replication at micromolar concentrations that was effective in feline, porcine and simian cells. As cyclophilins are highly conserved among mammals, F83233 could be a promising antiviral to treat different animal and zoonotic coronaviruses.

microbiology↗

bioRxiv2025

Mucin anchoring of SARS-CoV-2 neutralizing nanobinders increases intranasal antiviral efficacy

Respiratory viruses represent a major threat for human health, and despite effectiveness to limit the severity of the disease, they fail to block transmission. Recent advances have shown that the nasal cavity is the primal infection site of respiratory viruses, and thus represents a very attractive target for prophylactic treatment with antivirals in order to limit virus dissemination. However, mucociliary clearance limits the efficiency of a local treatment in the nasal cavity. We have previously developed a potent anti-Spike nanobinder blocking SARS-CoV-2 entry. Here, it was used as a proof of concept to show the strength of anchoring this synthetic antiviral to the mucin layer with a mucin-binding domain, increasing its residence time in the nasal cavity up to 6 hours post-instillation. This was very effective as a prophylactic treatment to limit infection of sentinel hamsters. Our strategy could be extended to antivirals against other major respiratory viruses such as RSV or influenza viruses, but also in other diseases by targeting specific epithelia increasing residence time and local concentration of the drug.

microbiology↗

bioRxiv2024

Inhibition of influenza virus replication by artificial proteins (αReps) targeting its RNA-polymerase

Seasonal epidemics and pandemics caused by influenza A viruses still represent a main public health burden in the world. Influenza viruses replicate and transcribe their genome in the nucleus of the infected cells, two functions that are supported by the viral RNA-dependent RNA-polymerase (FluPol) through extensive structural rearrangements and differential interactions with host cell factors. To get insights into its functioning, we screened a phage-display library of biosynthetic proteins (named Reps and build on a rigid alpha-helicoidal HEAT-like scaffold) against the structurally invariant FluPol core and several flexibly-linked domains of the FluPol PB2 subunit. Several Reps specific of the cap binding domain [CBD], the 627-domain and the NLS domain of the PB2 FluPol subunit displayed FluPol inhibitory and virus neutralization activities when transiently expressed in the cytosol. Furthermore, intracellular ectopic inducible expression of the Reps C3 and F3 (specific of the CBD and the 627-domain, respectively) in influenza virus permissive cells blocked transcription and multiplication of viruses representative of the H1N1, H3N2 and H7N1 subtypes, even when induced at late times post-infection. A synergic inhibitory effect on FluPol activity and virus multiplication was evidenced when the two Reps were covalently linked. These results suggest that i) interfering with FluPol structural rearrangements that are concomitant to its various activities may represent a promising strategy to block virus multiplication and to design new types of antivirals such as dual binders targeting distant sites on FluPol and ii) the 627-domain could be efficiently targeted to design influenza antivirals. Author SummaryThe influenza virus RNA-polymerase (FluPol) ensures genome transcription and replication in the nucleus of the infected cells. To select ligands able to interfere with FluPol functions, we screened a library of phages encoding biosynthetic proteins (named Reps) for binding to FluPol subunits and domains. When expressed intracellularly, several of them display efficient FluPol blocking and virus neutralizing activities. Reps C3 and F3 assembled through covalent linkages blocked FluPol activity more efficiently than their precursors. These Reps impaired multiplication of H1N1, H3N2 and H7N1 viruses, showing that their binding sites may constitute effective targets for new antiviral development.

microbiology↗

bioRxiv2023

Genome sequences of equine influenza A subtype H3N8 viruses by long read sequencing and functional characterization of the PB1-F2 virulence factor of A/equine/Paris/1/2018

Equine influenza virus (EIV) remains a persistent threat to equines, despite the availability of vaccines. Currently, strategies to monitor the virus and prevent any potential vaccine failure revolve around serological assays, RT-qPCR amplification, and sequencing the viral hemagglutinin (HA) and neuraminidase (NA) genes. These approaches overlook the contribution of other viral proteins in driving virulence. This study assesses the potential of long-read nanopore sequencing for swift and precise sequencing of circulating equine influenza viruses. To this end, two French Florida Clade 1 strains, including the one circulating in winter 2018-2019 exhibiting more pronounced pathogenicity than usual, as well as the two currently used OIE-recommended vaccine strains, were sequenced. Our results demonstrated the reliability of this sequencing method in generating accurate sequences. Sequence analysis of HA revealed a subtle antigenic drift in the French EIV strains, with specific substitutions, such as T163I in A/equine/Paris/1/2018 and the N188T mutation in post-2015 strains; both substitutions were located in antigenic site B. Antigenic site E exhibited modifications in post-2018 strains, with the N63D substitution. Segment 2 sequencing also revealed that the A/equine/Paris/1/2018 strain encodes a longer variant of the PB1-F2 protein when compared to other Florida clade 1 strains (90 amino acids long versus 81 amino acids long). Further biological and biochemistry assays demonstrated that this PB1-F2 variant has enhanced abilities to abolish the mitochondrial membrane potential {Delta}{Psi}m and permeabilize synthetic membranes. Altogether, our results highlight the interest in rapidly characterizing the complete genome of circulating strains with next-generation sequencing technologies to adapt vaccines and identify specific virulence markers of EIV.

microbiology↗

bioRxiv2023

Antiviral activity of intracellular nanobodies targeting the influenza virus RNA-polymerase core

Influenza viruses transcribe and replicate their genome in the nucleus of the infected cells, two functions that are supported by the viral RNA-dependent RNA-polymerase (FluPol). FluPol displays structural flexibility related to distinct functional states, from an inactive form to conformations competent for replication and transcription. FluPol machinery is constituted by a structurally-invariant core comprising the PB1 subunit stabilized with PA and PB2 domains, whereas the PA endonuclease and PB2 C-domains can pack in different configurations around the core. To get insights into the functioning of FluPol, we selected single-domain nanobodies (VHHs) specific of the influenza A FluPol core. When expressed intracellularly, several of them exhibited inhibitory activity on type A FluPol, but not on the type B one. The most potent VHH (VHH16) targets PA, but preferentially bind the PA-PB1 dimer with an affinity below the nanomolar range. Ectopic intracellular expression of VHH16 in virus permissive cells blocks multiplication of different influenza A subtypes, even when induced at late times post-infection. VHH16 was found to impair the transport of the PA-PB1 dimer to the nucleus, without affecting its handling by the importin {beta} RanBP5 and subsequent steps in FluPol assembly. These data suggest that the VHH16 neutralization activity is likely due to an alteration of the import of the PA-PB1 dimer into the nucleus, resulting to an inhibition of FluPol functioning. VHH16 binding site represent a potential target for antiviral development. Author SummaryThe influenza virus RNA-polymerase (FluPol) ensures genome transcription and replication in the nucleus of the infected cells. To select ligands able to block FluPol activities, we screened a library of phages encoding nanobodies and resulting from the immunization of a llama with FluPol subunits. When expressed intracellularly, one of the nanobodies displays highly efficient FluPol blocking and virus neutralizing activities. This nanobody binds FluPol with high affinity and recognizes preferentially the PA-PB1 assembled subunits. Furthermore, it was found to interfere with the transport of the PA-PB1 dimer into the nucleus, suggesting that targeting FluPol trafficking between the cytoplasm and the nucleus may constitute a powerful strategy to develop new antivirals.

microbiology↗

bioRxiv2019

Hepatitis C virus regulates its replication by maturing miR-122 through Akt-dependent phosphorylation of KSRP

The liver-specific micro-RNA-122 (miR-122) is required for the replication of hepatitis C virus (HCV). The direct interaction between miR-122 and the 5 untranslated region of the HCV genome promotes viral replication and protects HCV RNA from degradation. Because HCV RNA is its own substrate for replication, infected cells are submitted to the sequestration of increasing levels of miR-122 and to global de-repression of host miR-122 mRNA targets. Whether and how HCV regulates miR-122 maturation to create an environment favorable to its replication remains unexplored. We discovered that Akt-dependent phosphorylation of KSRP host protein at Serine residue 193 is essential for miR-122 maturation in hepatocytes. Moreover, we showed the existence of a reciprocal regulation loop where HCV replication can modulate the proviral effect mediated by KSRP-dependent maturation of miR-122. These data support a mechanism by which HCV regulates the expression of miR-122 by hijacking KSRP, thereby fueling its own replication.

microbiology↗