Potency and Breadth of Neutralization after 3 doses of mRNA vaccines in COVID-19 Convalescent and Naive individuals

Third doses of mRNA COVID-19 vaccines induced a significant increase in neutralizing potency and breadth in naive individuals comparable with convalescents who restored levels after the first two doses. These results suggest a limit to elicit neutralization in the number of stimuli by infection or vaccination with ancestral SARS-CoV-2 sequences

Potent Neutralizing Activity of Polyclonal Equine Antibodies against Omicron SARS-CoV-2

Using a polyclonal approach of equine anti-SARS-CoV-2 F(ab)2 antibodies we have achieved a high level of neutralizing potency against all SARS-CoV-2 variants tested. Neutralization titers were in the range of 105-106 IU/mL including Omicron: 111,403 UI/mL, which is 2-3 orders of magnitude what is normally achieved in response to SARS-CoV-2 infection and/or vaccination. The presence of high titers of a repertoire of antibodies targeting conserved epitopes in different regions of the spike protein could plausibly account for this remarkable breadth of neutralization. These results warrant the clinical investigation of anti-SARS-CoV-2 equine polyclonal F(ab)2 antibodies as a novel therapeutic strategy against COVID-19

DC/L-SIGN recognition of spike glycoprotein promotes SARS-CoV-2 trans-infection and can be inhibited by a glycomimetic antagonist

The efficient spread of SARS-CoV-2 resulted in a pandemic that is unique in modern history. Despite early identification of ACE2 as the receptor for viral spike protein, much remains to be understood about the molecular events behind viral dissemination. We evaluated the contribution of C-type lectin receptors (CLRS) of antigen-presenting cells, widely present in air mucosa and lung tissue. DC-SIGN, L-SIGN, Langerin and MGL bind to diverse glycans of the spike using multiple interaction areas. Using pseudovirus and cells derived from monocytes or T-lymphocytes, we demonstrate that while virus capture by the CLRs examined does not allow direct cell infection, DC/L-SIGN, among these receptors, promote virus transfer to permissive ACE2+ cells. A glycomimetic compound designed against DC-SIGN, enable inhibition of this process. Thus, we described a mechanism potentiating viral capture and spreading of infection. Early involvement of APCs opens new avenues for understanding and treating the imbalanced innate immune response observed in COVID-19 pathogenesis