The development of a novel SARS-CoV-2 virus neutralizing immunotoxin

For decades, scientific efforts were focused on the improvement of the effectiveness of the therapeutic antibodies, mainly in order reduce the dosage and thus lower the side-effects and costs. P4A1, a potent SARS-CoV-2 virus neutralizing antibody was already engineered to contain Fc fragment mutations, that dramatically increased the blood circulation time. In this work, we aimed to further enhance this neutralizing antibody efficacy by creating a next-generation virus neutralizing agent based on the P4A1 and conjugated with a highly processive Bacillus amyloliquefaciens RNase (barnase). Barnase itself is known to act as a mild toxin that drives the cells to apoptosis, and we propose that its RNase activity may enhance the protective effect through the hydrolysis of viral RNA in infected cells, and thereby additionally preventing pathogen replication. The main challenge in the assembly of such molecule is the intrinsic barnase toxicity in mammalian cells, what precludes the possibility to express it as a fusion protein. Further, we had shown that barnase, being a small (12.5 kDa) protein, contains very few surface reactive moieties that are available for conventional chemical crosslinking strategies. Therefore, the antibody-barnase fusion protein was obtained by enzymatic conjugation via the sortase A enzyme. The reaction conditions for bacterially expressed barnase and HEK293 derived P4A1 modified to contain heavy chain C-terminal sortase motif were thoroughly optimized and the reaction yield approached 80%. The immunotoxin RBD binding EC50 was not found to differ from the unconjugated P4A1 antibody and barnase activity was found to be 33% of the one for unmodified enzyme. Thus, we obtained the promising immunotoxin with a good yield, which had retained its RNase activity for the further in vitro virus neutralization studies.

Detraining Effects of COVID-19 Pandemic on Physical Fitness, Cytokines, C-Reactive Protein and Immunocytes in Men of Various Age Groups.

Background and Objectives: Since the start of the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus II, levels of physical inactivity have become more severe and widespread than ever before. Physical inactivity is known to have a negative effect on the human body, but the extent to which reduced physical fitness has effected immune function before and after the current pandemic has not yet been uncovered. The aim of this study was to investigate the detraining effects of the COVID-19 confinement period on physical fitness, immunocytes, inflammatory cytokines, and proteins in various age groups. The participants of this study included sixty-four male adults who did not exercise during the pandemic, although they had exercised regularly before. Materials and Methods: Participants were classified by age group, which included the 20s group (20s'G, n = 14), 30s group (30s'G, n = 12), 40s group (40s'G, n = 12), 50s group (50s'G, n = 12), and 60s group (60s'G, n = 14). Results: Regarding body composition, muscle mass significantly decreased, whereas fat mass, fat percentage, and waist/hip ratio significantly increased in most groups. Cardiopulmonary endurance and strength significantly decreased in all groups, while muscle endurance and flexibility decreased in some groups compared to the pre-COVID-19 pandemic. This study confirmed the immunocytopenia and enhanced inflammation due to physical inactivity during the COVID-19 pandemic, and a greater detrimental decrease mainly after the age of 50. Conclusion: This study confirmed a decrease in physical fitness after the start of the COVID-19 pandemic, characterized by an increase in fat mass and a decrease in muscle mass, thereby increasing cytokines and reducing immunocytes in the body. While social distancing is important during the pandemic, maintaining physical fitness should also be a top priority.

Antiviral Activity of Ribosome-Inactivating Proteins.

Ribosome-inactivating proteins (RIPs) are rRNA N-glycosylases from plants (EC 3.2.2.22) that inactivate ribosomes thus inhibiting protein synthesis. The antiviral properties of RIPs have been investigated for more than four decades. However, interest in these proteins is rising due to the emergence of infectious diseases caused by new viruses and the difficulty in treating viral infections. On the other hand, there is a growing need to control crop diseases without resorting to the use of phytosanitary products which are very harmful to the environment and in this respect, RIPs have been shown as a promising tool that can be used to obtain transgenic plants resistant to viruses. The way in which RIPs exert their antiviral effect continues to be the subject of intense research and several mechanisms of action have been proposed. The purpose of this review is to examine the research studies that deal with this matter, placing special emphasis on the most recent findings.