Biology subjects

Ruetalo, N.

Publications and source records attributed to Ruetalo, N..

4 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↗

bioRxiv2020

Rapid and efficient inactivation of surface dried SARS-CoV-2 by UV-C irradiation

BackgroundThe SARS-CoV-2 pandemic urges for cheap, reliable, and rapid technologies for disinfection and decontamination. One frequently proposed method is UV-C irradiation. However, UV-C doses necessary to achieve inactivation of high-titer SARS-CoV-2 are poorly defined. MethodsUsing a box and two handheld systems designed to decontaminate objects and surfaces we evaluated the efficacy of 254 nm UV-C treatment to inactivate surface dried SARS-CoV-2. ResultsDrying for two hours did not have a major impact on the infectivity of SARS-CoV-2, indicating that exhaled virus in droplets or aerosols stays infectious on surfaces at least for a certain amount of time. Short exposure of high titer surface dried virus (3-5*10^6 IU/ml) with UV-C light (16 mJ/cm2) resulted in a total inactivation of SARS-CoV-2. Dose-dependency experiments revealed that 3.5 mJ/cm2 were still effective to achieve a > 6-log reduction in viral titers whereas 1.75 mJ/cm2 lowered infectivity only by one order of magnitude. ConclusionsOur results demonstrate that SARS-CoV-2 is rapidly inactivated by relatively low doses of UV-C irradiation. Furthermore, the data reveal that the relationship between UV-C dose and log-viral titer reduction of surface residing SARS-CoV-2 is non-linear. In the context of UV-C-based technologies used to disinfect surfaces, our findings emphasize the necessity to assure sufficient and complete exposure of all relevant areas by integrated UV-C doses of at least 3.5 mJ/cm2 at 254 nm. Altogether, UV-C treatment is an effective non-chemical possibility to decontaminate surfaces from high-titer infectious SARS-CoV-2.

microbiology↗

bioRxiv2020

NeutrobodyPlex - Nanobodies to monitor a SARS-CoV-2 neutralizing immune response

As the COVID-19 pandemic escalates, the need for effective vaccination programs, therapeutic intervention, and diagnostic tools increases. Here, we identified 11 unique nanobodies (Nbs) specific for the SARS-CoV-2 spike receptor-binding domain (RBD) of which 8 Nbs potently inhibit the interaction of RBD with angiotensin-converting enzyme 2 (ACE2) as the major viral docking site. Following a detailed epitope determination and characterization of the binding mode by structural analysis, we constructed a hetero-bivalent Nb targeting two different epitopes within the RBD:ACE2 interface. This resulted in a high-affinity binder with a viral neutralization efficacy in the picomolar range. Using the bivalent Nb as a surrogate, we established a competitive multiplex binding assay ("NeutrobodyPlex") for detailed analysis of the presence and performance of neutralizing RBD-binding antibodies in the serum of convalescent or vaccinated patients. As demonstrated, the NeutrobodyPlex enables high-throughput screening and detailed analysis of neutralizing immune responses in infected or vaccinated individuals, helping to monitor immune status or guide vaccine design. This approach is easily transferrable to diagnostic laboratories worldwide.

immunology↗

bioRxiv2019

The human α-defensin-derived peptide HD5(1-9) inhibits cellular attachment and entry of human cytomegalovirus.

Human cytomegalovirus (HCMV) infection causes severe illness in newborns and immunocompromised patients. Since treatment options are limited there is an unmet need for new therapeutic approaches. Defensins are cationic peptides, produced by various human tissues, which serve as antimicrobial effectors of the immune system. Furthermore, some defensins are proteolytically cleaved, resulting in the generation of smaller fragments with increased activity. Together, this led us to hypothesize that defensin-derived peptides are natural human inhibitors of virus infection with low toxicity. We screened several human defensin HNP4- and HD5-derived peptides and found HD5(1-9) to be antiviral without toxicity at high concentrations. HD5(1-9) inhibited HCMV cellular attachment and thereby entry and was active against primary as well as a multiresistant HCMV isolate. Moreover, cysteine and arginine residues were identified to mediate the antiviral activity of HD5(1-9). Altogether, defensin-derived peptides, in particular HD5(1-9), qualify as promising candidates for further development as a novel class of HCMV entry inhibitors.\n\nAUTHOR SUMMARYDefensins are peptides produced by various human organs which take part in the natural defense against pathogens. Recently, it has been shown that defensins are further cleaved to smaller peptides that have high intrinsic anti-microbial activity. We here challenged the hypothesis that these peptides might have antiviral activity, and due to their presumably natural occurrence, low toxicity. Indeed, we found one peptide fragment that turned out to block the attachment of the human cytomegalovirus (HCMV) to cells. Furthermore, this peptide did not show toxicity in various cellular assays or impede the embryonic development of zebrafish at the concentrations used to block HCMV. This is important, since HCMV is one of the most important viral congenital infections. Altogether, our results hold promise for the development of a new class of antivirals against HCMV.

microbiology↗