Lectins (specifically S.Nigra Agglutinins SNAs) from elderberries have a high affinity to bind with sialic acids found ion the membrane surface of health cells, which influenza A also uses to enter the host cell (by triggering endocytosis). Lectins therefore complete with the virus in binding to these sialic acids.
Sialic acids are found in large concentration on the cell membranes of cells in the upper respiratory system which are targeted especially by influenza virus.
