Characterization of the C6D7-RBD Human Monoclonal Antibody Specific to the SARS-CoV-2 S Protein Receptor-Binding Domain.

The new coronavirus infection COVID-19 is an acute viral disease that affects primarily the upper respiratory tract. The etiological agent of COVID-19 is the SARS-CoV-2 RNA virus (Coronaviridae family, Betacoronavirus genus, Sarbecovirus subgenus). We have developed a high-affinity human monoclonal antibody, called C6D7-RBD, which is specific to the S protein receptor-binding domain (RBD) from the SARS-CoV-2 Wuhan-Hu-1 strain and exhibits virus-neutralizing activity in a test with recombinant antigens: angiotensin-converting enzyme 2 (ACE2) and RBD.

[Antibiotic-dependent selection of the E. coli clones with increased chaperone activity for highly-efficient production of the full-length soluble New Delhi metallo-beta-lactamase].

The spread of the New Delhi metallo-beta-lactamase (NDM-1), a plasmid-borne enzyme conferring bacterial resistance to any known beta-lactam antibiotics, represents the global health threat. There is an urgent need to develop the efficient NDM-1 inhibitors of various mode of action thereby necessitating structural studies of the enzyme as well as analysis of the secretion pathway and localization of the protein. The recombinant full-length NDM-1 is produced in E. coli in the inactive form and is mostly accumulated in the inclusion bodies. The secreted recombinant NDM-1 forms are several N-terminally truncated species. The robust expression system capable of high-level production of the full-length NDM-1 and derivatives thereof is required to obtain NDM-1 in the quantities necessary for drug discovery, diagnostics, and research purposes. Therefore, we developed a new system that utilizes antibiotic pressure to select E. coli producing increased quantity of soluble NDM-1 and showed that an increase in the NDM-1 solubility occurs in the bacterial clones producing increased amounts in the chaperones.

Role of Structure-Based Changes due to Somatic Mutation in Highly Homologous DNA-Binding and DNA-Hydrolyzing Autoantibodies Exemplified by A23P Substitution in the VH Domain.

Anti-DNA autoantibodies are responsible for tissue injury in lupus. A subset of DNA-specific antibodies capable of DNA cleavage can be even more harmful after entering the living cells by destroying nuclear DNA. Origins of anti-DNA autoantibodies are not fully understood, and the mechanism of induction of DNA-cleaving activity remains speculative. The autoantibody BV04-01 derived from lupus-prone mouse is the only DNA-hydrolyzing immunoglobulin with known 3D structure. Identification and analysis of antibodies homologous to BV04-01 may help to understand molecular bases and origins of DNA-cleaving activity of autoantibodies. BLAST search identified murine anti-DNA autoantibody MRL-4 with sequences of variable region genes highly homologous to those of autoantibody BV04-01. Despite significant homology to BV04-01, not only MRL-4 had no DNA-cleaving activity, but also reversion of its unusual P23 mutation to the germline alanine resulted in a dramatic loss of affinity to DNA. Contrary to this effect, transfer of the P23 mutation to the BV04-01 has resulted in a significant drop in DNA binding and almost complete loss of catalytic activity. In the present paper we analyzed the properties of two homologous autoantibodies and mutants thereof and discussed the implications of unusual somatic mutations for the development of autoantibodies with DNA-binding and DNA-hydrolyzing activity.