Research progress on the BCG-induced trained immunity:mechanism and role

ABSTRACT

The purpose of Bacillus Calmette-Guérin (BCG) vaccination is to prevent Mycobacterium tuberculosis infection, but studies have shown that BCG activates innate immunity, causes epigenetic reprogramming and metabolic changes of myeloid cells, and forms innate immune memory or trained immunity. When bone marrow-like cells are stimulated by pathogens again, they show enhanced immune response and promote the host's nonspecific defense ability. Innate immune memory is also called training immunity. In recent years, BCG-induced innate immune memory has attracted much attention, and it will guide the design of novel vaccine. This article reviews the application of BCG in prevention and treatment of corone virus disease 2019, the non-specific protection and mechanism of BCG-mediated trained immunity.