Explain how the HPV vaccine produces long-term immunity in individuals.

A vaccination is where tiny particles are introduced into the body to stimulate the immune system to defend itself against a micro-organism. Human Papilloma Virus (HPV) antigens are included in the HPV vaccine. These antigens are detected by the innate immune system. White blood cells such as phagocytes ingest these antigens and then present them on their cell surfaces. These white blood cells then travel to lymph nodes where they present the HPV antigens to T-Helper cells.

These cells activate the immune response. The immune response has many components:  

• an inflammatory response is triggered. This brings more white blood cells to the area.  

• the T helper cells activate B cells. 

T cells that detect the HPV antigen rapidly divide by clonal expansion. This is via mitosis, a 5 step process of interphase, prophase, metaphase, anaphase, telophase. There are two types of B cells that match the antigen presented by the T helper cells; memory B cells and plasma cells. Plasma cells release many antibodies against the HPV antigen. Memory B cells migrate to the lymph node where they will stay. These memory B cells last for years and if the HPV antigen is encountered again in future, they would convey immunity. The memory cells may require stimulating after a period of about 10 years with a booster vaccine.  This process conveys immunised individuals with protection against HPV. As HPV is associated with cervical cancer, it reduces the risk of immunised females developing cervical cancer.