Repeated exposure to viruses or their antigens elicits anamnestic antibody responses that produce antibodies that are of greater magnitude and affinity compared to those induced after primary exposure to antigen.The anamnestic nature of the response is a result of the recall of memory Bcells (MBCs) that have undergone clonal expansion and affinity maturation in germinal centers(GCs) during the primary response. Upon antigen re-encounter (“boosting”), MBCs, aided by enhanced help from memory T cells, efficiently differentiate into antibody-secreting plasma cells.