BCG, muramylpeptides, trained immunity (part II): a low molecular weight alternative to multicomponent bacterial immunostimulants for prevention of respiratory infections during a pandemic

During a pandemic, nonspecific immunoprophylaxis of SARS-CoV-2 infection and other acute respiratory infections (ARI), which can worsen the course COVID-19, is increasingly in demand addition to specific immunization. BCG vaccine appears be one candidate immunostimulants this regard. At same time, microbe-derived preparations capable inducing state trained immunity deserve attention. bacterial immunostimulatory agents containing large number biologically active subunits have long been considered as objects search for promising pharmacological substances. The review analyzes linkages between BCG, mycobacterial adjuvants, lysates, immunity, muramylpeptides (MPs) NOD2 receptors light choice low molecular weight alternative multicomponent ARI prevention during COVID-19 pandemic. key molecules by bacteria stimulate innate adaptive immune responses proceeds spiral. On different loops spiral, MPs repeatedly reproduced effects vaccines immunostimulants. peptidoglycans determine adjuvant properties cell walls mycobacteria their peptide-glycolipid fraction (wax D). were able replace Mycobacterium tuberculosis complete Freunds adjuvant. NOD2-dependent ability induce immunity. Probably, provide NOD2-mediated long-term prophylactic action lysates. All above has prompted revisiting previously obtained evidence efficacy glucosaminylmuramyl dipeptide (GMDP) agonist treatment/prevention infections. We speculate here that MPs, particular GMDP, at rational dosing regimens will reproduce many aspects preventing pandemic post-pandemic period.