Ligand concentration determines antiviral efficacy of silica multivalent nanoparticles

We have learned from the recent COVID-19 pandemic that the emergence of a new virus can quickly become a global health burden and kill millions of lives. Antiviral drugs are essential in our fight against viral diseases, but most of them are virus-specific and are prone to viral mutations. We have developed broad-spectrum antivirals based on multivalent nanoparticles grafted with ligands that mimic the target of viral attachment ligands (VALs). We have shown that when the ligand has a sufficiently long hydrophobic tail, the inhibition mechanism switches from reversible (virustatic) to irreversible (virucidal). Here, we investigate further how ligand density and particle size affect antiviral efficacy, both in terms of half-inhibitory concentration (IC50) and of reversible vs irreversible mechanism. We designed antiviral silica nanoparticles modified with 11-mercaptoundecane-1-sulfonic acid (MUS), a ligand that mimics heparan sulfate proteoglycans (HSPG) and we showed that these nanoparticles can be synthesized with different sizes (4-200 nm) and ligand grafting densities (0.59-10.70 /nm2). By testing these particles against herpes simplex virus type 2 (HSV-2), we show that within the size and density ranges studied, the antiviral IC50 is determined solely by equivalent ligand concentration. The nanoparticles are found to be virucidal at all sizes and densities studied.

Soft Multimaterial Magnetic Fibers and Textiles

Magnetically responsive soft materials are promising building blocks for the next generation of soft robotics, prosthesis, surgical tools, and smart textiles. To date, however, the fabrication of highly integrated magnetic fibers with extreme aspect ratios, that can be used as steerable catheters, endoscopes, or within functional textiles remains challenging. Here, multimaterial thermal drawing is proposed as a material and processing platform to realize 10s of meters long soft, ultrastretchable, yet highly resilient magnetic fibers. Fibers with a diameter as low as 300 µm and an aspect ratio of 105 are demonstrated, integrating nanocomposite domains with ferromagnetic microparticles embedded in a soft elastomeric matrix. With the proper choice of filler content that must strike the right balance between magnetization density and mechanical stiffness, fibers withstanding strains of >1000% are shown, which can be magnetically actuated and lift up to 370 times their own weight. Magnetic fibers can also integrate other functionalities like microfluidic channels, and be weaved into conventional textiles. It is shown that the novel magnetic textiles can be washed and sustain extreme mechanical constraints, as well as be folded into arbitrary shapes when magnetically actuated, paving the way toward novel intriguing opportunities in medical textiles and soft magnetic systems.

NGS method by library enrichment for rapid pestivirus purity testing in biologics

NGS sequencing was evaluated to understand its added value for animal health vaccine candidates. We have previously established the proof of concept for its application in purity testing on several Master Seeds. Here we evaluate the NGS method after enrichment to detect pestiviruses. To achieve this, we conducted a spiking study using 6 viruses, consisting of 3 pestiviruses and 3 other RNA-viruses at different concentrations into cell suspension. A deep Illumina random sequencing of all nucleic acids (DNA and RNA) was performed. The bioinformatics analysis including both assembly into contigs and annotation were processed using viral public databases for the spiked viruses' identification. Here we present the results of spiking experiments for the simultaneous spike of 6 viruses at 100-10 and 1 TCID₅₀/ml. Using Illumina sequencing, the 3 pestiviruses were all detected at the highest concentration, and even at the lowest one such as 1 TCID₅₀/ml for CSFV. Regarding the other viruses, they were not detected at all. Overall, the study showed consistent results for specific detection of pestiviruses with an increase of sensitivity after enrichment. The sensitivity of NGS evaluated by virus spiking experiments of cells demonstrated that NGS method is a valuable and sensitive tool for specific agent detection required in purity testing during vaccine development. This NGS method should be considered as an alternative tool of current purity testing for the prospective testing of biological products.

Involvement of the Wnt pathway in BVDV cytopathogenic strain replication in primary bovine cells

Background

Bovine viral diarrhea virus 1 (BVDV-1) of the pestivirus genus is an economically crippling virus in the cattle industry; this positive RNA virus causes mucosal disease resulting in reproductive losses and other disease syndromes. The pathogenesis mechanism of the disease caused by BVDV infection is not well understood; for a better understanding of in vivo host BVDV-1 interactions, we conducted a transcriptomic study of infected cells at different times post-infection.

Methods

We compared the permissiveness and cellular response of a BVDV-1 cytopathogenic strain on Madin-Darby Bovine Kidney cells (MDBK) and bovine lung primary cells, a model closer to in vivo infection. Then a RNAseq analysis was realized on the infected bovine lung primary cells, at 10 hpi and 30 hpi (hours post-infection), to identify transcriptomic signatures.

Results

RNAseq analysis on BVDV-1 infected bovine primary cells showed 2,759 and 5,376 differentially expressed genes at respectively 10 hpi and 30 hpi with an absolute Fold Change  ≥ 2. Among the different pathways deregulated, data analysis revealed a deregulation of Wnt signaling pathway, a conserved process that play a critical role in embryogenesis, cellular proliferation, and differentiation as well as in viral responses against viruses such as Influenza or Hepatitis C. We demonstrated here that the deregulation of the Wnt/βcatenin signaling pathway plays a role in viral replication of BVDV cp strain. Interestingly, we showed that the inhibition of this Wnt pathway using two inhibitors, FZM1 and iCRT14, induced a delay in onset of the establishment of a cytopathic effect of primary cells.

Conclusions

Thereby, this study highlighted a role of the Wnt signaling pathway in the BVDV-1 viral replication in bovine cells, suggesting an interesting option to explore as a new therapeutic target.