Biology subjects

Schnepf, D.

Publications and source records attributed to Schnepf, D..

3 recordsLinked to original sources

bioRxiv2021

A broadly neutralizing biparatopic Nanobody protects mice from lethal challenge with SARS-CoV-2 variants of concern

The ongoing COVID-19 pandemic and the frequent emergence of new SARS-CoV-2 variants of concern (VOCs), requires continued development of fast and effective therapeutics. Recently, we identified high-affinity neutralizing nanobodies (Nb) specific for the receptor-binding domain (RBD) of SARS-CoV-2, which are now being used as biparatopic Nbs (bipNbs) to investigate their potential as future drug candidates. Following detailed in vitro characterization, we chose NM1267 as the most promising candidate showing high affinity binding to several recently described SARS-CoV-2 VOCs and strong neutralizing capacity against a patient isolate of B.1.351 (Beta). To assess if bipNb NM1267 confers protection against SARS-CoV-2 infection in vivo, human ACE2 transgenic mice were treated by intranasal route before infection with a lethal dose of SARS-CoV-2. NM1267-treated mice showed significantly reduced disease progression, increased survival rates and secreted less infectious virus via their nostrils. Histopathological analyses and in situ hybridization further revealed a drastically reduced viral load and inflammatory response in lungs of NM1267-treated mice. These data suggest, that bipNb NM1267 is a broadly active and easily applicable drug candidate against a variety of emerging SARS-CoV-2 VOCs.

biochemistry↗

bioRxiv2021

Drug development of an affinity enhanced, broadly neutralizing heavy chain only antibody that restricts SARS-CoV-2 in hamsters

We have identified camelid single-domain antibodies (VHHs) that cross-neutralize SARS-CoV-1 and -2, such as VHH72, which binds to a unique highly conserved epitope in the viral receptor-binding domain (RBD) that is difficult to access for human antibodies. Here, we establish a protein engineering path for how a stable, long-acting drug candidate can be generated out of such a VHH building block. When fused to human IgG1-Fc, the prototype VHH72 molecule prophylactically protects hamsters from SARS-CoV-2. In addition, we demonstrate that both systemic and intranasal application protects hACE-2-transgenic mice from SARS-CoV-2 induced lethal disease progression. To boost potency of the lead, we used structure-guided molecular modeling combined with rapid yeast-based Fc-fusion prototyping, resulting in the affinity-matured VHH72_S56A-Fc, with subnanomolar SARS-CoV-1 and -2 neutralizing potency. Upon humanization, VHH72_S56A was fused to a human IgG1 Fc with optimized manufacturing homogeneity and silenced effector functions for enhanced safety, and its stability as well as lack of off-target binding was extensively characterized. Therapeutic systemic administration of a low dose of VHH72_S56A-Fc antibodies strongly restricted replication of both original and D614G mutant variants of SARS-CoV-2 virus in hamsters, and minimized the development of lung damage. This work led to the selection of XVR011 for clinical development, a highly stable anti-COVID-19 biologic with excellent manufacturability. Additionally, we show that XVR011 is unaffected in its neutralizing capacity of currently rapidly spreading SARS-CoV-2 variants, and demonstrate its unique, wide scope of binding across the Sarbecovirus clades.

molecular biology↗

bioRxiv2021

Rotavirus susceptibility of antibiotic-treated mice ascribed to diminished expression of interleukin-22

The commensal microbiota regulates susceptibility to enteric pathogens by fine-tuning mucosal innate immune responses, but how susceptibility to enteric viruses is shaped by the microbiota remains incompletely understood. Past reports have indicated that commensal bacteria may either promote or repress rotavirus replication in the small intestine of mice. We now report that rotavirus replicated more efficiently in the intestines of germ-free and antibiotic-treated mice compared to animals with an unmodified microbiota. Antibiotic treatment also facilitated rotavirus replication in type I and type III interferon (IFN) receptor-deficient mice, revealing IFN-independent proviral effects. Expression of interleukin-22 (IL-22) was strongly diminished in the intestine of antibiotic-treated mice. Treatment with exogenous IL-22 blocked rotavirus replication in microbiota-depleted wild-type and Stat1-/- mice, demonstrating that the antiviral effect of IL-22 in animals with altered microbiome is not dependent on IFN signaling. In antibiotic-treated animals, IL-22-induced a specific set of genes including Fut2, encoding fucosyl-transferase 2 that participates in the biosynthesis of fucosylated glycans which can mediate rotavirus binding. Interestingly, IL-22 also blocked rotavirus replication in antibiotic-treated Fut2-/- mice. Furthermore, IL-22 inhibited rotavirus replication in antibiotic-treated mice lacking key molecules of the necroptosis or pyroptosis pathways of programmed cell death. Taken together, our results demonstrate that IL-22 determines rotavirus susceptibility of antibiotic-treated mice, yet the IL-22-induced effector molecules conferring rotavirus resistance remain elusive.

immunology↗