Mevel, E. | Search bioRxiv

bioRxiv2022

Anti-SARS-CoV-2 swine glyco-humanized polyclonal antibody XAV-19 retains neutralizing activity against SARS-CoV-2 B.1.1.529 (Omicron)

B.1.1.529 is the SARS-CoV-2 variant designated Omicron by the WHO in November 2021. It is a highly divergent variant with a high number of mutations, including 26-32 mutations in the spike protein among which 15 in the Receptor Binding Domain (RBD) including at the human angiotensin converting enzyme 2 (ACE-2) receptor interacting interface. Because of a decreased affinity for the ACE-2 receptor and a geometric reorganization of the S1-S2 cleavage site, the Omicron variant is predicted to not have a significant infectivity advantage over the delta variant and to be less pathogenic than Delta. However, in Omicron, neutralizing epitopes are greatly affected, suggesting that current vaccines and neutralizing monoclonal antibodies might confer reduced protection against this variant. In contrast, we and others previously demonstrated that polyclonal antibodies against SARS-CoV-2 RBD obtained from hyperimmunized animal hosts do maintain their neutralizing properties against Alpha to Delta. Here, we confirmed these findings by showing that XAV-19, a swine glyco-humanized polyclonal antibody retains full neutralizing activity against Omicron.

immunology↗

bioRxiv2020

Generation of two Multipotent Mesenchymal Progenitor Cell Lines Capable of Osteogenic, Mature Osteocyte, Adipogenic, and Chondrogenic Differentiation

Differentiation of multi-potent mesenchymal progenitor cells give rise to several tissue types including bone, cartilage, and adipose. In addition to the complication arising from the numerous spatial, temporal, and hormonal factors that regulate lineage allocation, targeting of these cells in vivo is challenging, making mesenchymal progenitor cell lines valuable tools to study both tissue development and the differentiated cell types. Mesenchymal stem cells (MSCs) can be isolated from humans and animals; however, obtaining homogenous, responsive cells in a reproducible fashion can be problematic. As such, we have developed two novel mesenchymal progenitor cell (MPC) lines, MPC1 and MPC2, which were generated from the bone marrow of male C57BL/6 mice. These cells were immortalized using the temperature sensitive large T-antigen, allowing for thermal control of proliferation and differentiation. Both MPC1 and MPC2 cell lines are capable of osteogenic, adipogenic, and chondrogenic differentiation. Under osteogenic conditions both cell lines formed discrete mineralized nodules, staining for alizarin red and alkaline phosphatase, while expressing high levels of osteogenic genes including Sost, Fgf23, and Dmp1. Sost and Dmp1 mRNA levels were drastically reduced with parathyroid hormone, thus recapitulating in vivo responses. MPC cells secreted both the intact (iFGF23) and C-terminal (cFGF23) forms of endocrine hormone FGF23, which was upregulated in the presence of 1,25 dihydroxy vitamin D (1,25D). In addition to osteogenic differentiation, both cell lines also rapidly entered the adipogenic lineage, expressing several adipose markers after only 4 days in adipogenic media. MPC cells were also capable of chondrogenic differentiation, displaying increased expression of common cartilage genes including aggrecan, sox9, and cartilage oligomeric matrix protein. With the ability to differentiate into multiple mesenchymal lineages and mimic in vivo responses of key regulatory genes/proteins, MPC cells are a valuable model to study factors that regulate mesenchymal lineage allocation as well as the mechanisms that dictate transcription, protein modification, and secretion of these factors.

cell biology↗