[The effect of phycocyanins from Arthrospira platensis on the efficacy of immunization with an anti-coronavirus vaccine in vivo].

The creation of food for special dietary use designed to increase the resistance of the human immune system to viral infections is an vital section of modern nutrition science. Phycocyanins (PC) of the Arthrospira platensis food cyanobacterium possess potential immunomodulatory properties. The study of the possibility of using PC as oral immunostimulants and/or immunoadjuvants in vaccination scenarios is of significant interest. The purpose of this research was to study the ability of PC concentrate and PC complex with egg protein (Module) to influence the state of cell-mediated and humoral immunity in laboratory rodents - BALB/c mice on the developed model of attenuated vaccination with Sputnik-V. Material and methods. The experiment involved 34 male BALB/c mice with an initial body weight of 20.0±1.0 g at the age of 4-5 weeks. 5 groups were formed: "Control", "PC-200", "PC-420", "Module-200" and "Module-420". The PC concentrate and the Module were administered orally daily for 49 days at doses of 200 and 420 mg/kg body weight (in terms of PC). The Sputnik-V vaccine for the prevention of human SARS-CoV-2 coronavirus infection was administered to all animals on days 29 and 50. When studying the immunoadjuvant potential of PC concentrate and Module on days 49, 57, 64, 141 and 171, IgG levels to SARS-CoV-2 were assessed by enzyme-linked immunosorbent assay. On days 28, 31 and 51, immunostimulating properties were evaluated by cytometry by means of immunophenotyping blood lymphocytes. At the end of the experiment, integral, hematological, and biochemical (blood serum) parameters were evaluated on day 190. Results. When evaluating the immunoadjuvant properties of PC concentrate and Module on day 64, a significant increase in IgG titers to 1/115 000 and 1/128 000 was observed in Module-200 and Module-420 groups, respectively. In the Module-200 group, on day 141, the concentration of antibodies was almost 2 fold higher than the control ones. From days 141 to 171, increased antibody titers were observed in all experimental groups compared with the control. When studying the immunostimulating properties of the surveyed objects on the 31st day of the experiment, an increase in the number of cytotoxic T-cell subpopulations by 29 and 42%, respectively, was found in the Module-200 and Module- 420 groups. At the end of the experiment, minor shifts in blood biochemical parameters were revealed, there were no changes in hematological parameters; an 11.7% increase in heart mass was found in the Module-420 group. Conclusion. The experiment demonstrated the presence of immunoadjuvant properties in PC concentrate and Module, especially expressed in the Module-200 group. The Module had immunostimulating effect on cell-mediated immunity. The manifestation of the Module effects, in contrast to the PC concentrate, is apparently due to its better stability in the gastrointestinal tract environment. Further studies of the secretory activity of immunocompetent cells are needed, which may shed light on the nature of the effect of PC on key parts of the immune system.