A nanobody recognizes a unique conserved epitope and potently neutralizes SARS-CoV-2 omicron variants.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) Omicron variant sub-lineages spread rapidly worldwide, mostly due to their immune-evasive properties. This has put a significant part of the population at risk for severe disease and underscores the need for effective anti-SARS-CoV-2 agents against emergent strains in vulnerable patients. Camelid nanobodies are attractive therapeutic candidates due to their high stability, ease of large-scale production, and potential for delivery via inhalation. Here, we characterize the receptor binding domain (RBD)-specific nanobody W25 and show superior neutralization activity toward Omicron sub-lineages in comparison to all other SARS-CoV2 variants. Structure analysis of W25 in complex with the SARS-CoV2 spike glycoprotein shows that W25 engages an RBD epitope not covered by any of the antibodies previously approved for emergency use. In vivo evaluation of W25 prophylactic and therapeutic treatments across multiple SARS-CoV-2 variant infection models, together with W25 biodistribution analysis in mice, demonstrates favorable pre-clinical properties. Together, these data endorse W25 for further clinical development.

[Assessing Convalescent Plasma Efficacy in Moderate COVID-19 Hospitalizations: A Bicentric Retrospective Study]. / Uso de plasma de convalecientes de COVID-19 en pacientes hospitalizados por SARS-CoV-2 de moderada grave-dad en la Región de Los Ríos, Chile.

INTRODUCTION: COVID-19 claimed millions of lives, mainly in the pre-vaccine era. Preliminary studies showed promising efficacy of convalescent plasma against SARS-CoV-2 (CP). OBJECTIVE: To evaluate the efficacy of CP in patients hospitalized for COVID-19 with moderate severity. METHODS: Retrospective, bicentric study including adults hospitalized for moderate (non-critical) COVID-19 who required oxygen therapy. CP donated by survivors of mild cases (600 cc) were searched for IgG anti-SARS-CoV-2. Its impact on mortality, hospital stay (days), and need for mechanical ventilation (IMV) was evaluated. RESULTS: Of the 119 patients included, 58% were men (median age 60 years), 88% had comorbidity, and 43% had a high-risk CALL score. Forty-three patients (36%) received CP, only 15 (12.6%) early (< 7 days). Twenty-two patients had to be transferred to the intensive care unit; 18 received IMV, and 15 died (12.6%). The use of CP was not associated with changes in mortality (p = 0.16), need for IMV (p = 0.79), or hospital stay (p = 0.24). Its early administration (< 7 days of symptoms) did not show a significant association either. The presence of heart disease and subsequently requiring IMV were independent factors of mortality. CONCLUSIONS: The use of CP in patients hospitalized for moderately severe COVID-19 was not associated with lower mortality, hospital stay, or the need for IMV.

Potent neutralization of clinical isolates of SARS-CoV-2 D614 and G614 variants by a monomeric, sub-nanomolar affinity nanobody.

Despite unprecedented global efforts to rapidly develop SARS-CoV-2 treatments, in order to reduce the burden placed on health systems, the situation remains critical. Effective diagnosis, treatment, and prophylactic measures are urgently required to meet global demand: recombinant antibodies fulfill these requirements and have marked clinical potential. Here, we describe the fast-tracked development of an alpaca Nanobody specific for the receptor-binding-domain (RBD) of the SARS-CoV-2 Spike protein with potential therapeutic applicability. We present a rapid method for nanobody isolation that includes an optimized immunization regimen coupled with VHH library E. coli surface display, which allows single-step selection of Nanobodies using a simple density gradient centrifugation of the bacterial library. The selected single and monomeric Nanobody, W25, binds to the SARS-CoV-2 S RBD with sub-nanomolar affinity and efficiently competes with ACE-2 receptor binding. Furthermore, W25 potently neutralizes SARS-CoV-2 wild type and the D614G variant with IC50 values in the nanomolar range, demonstrating its potential as antiviral agent.