Germinal centers are areas in the lymph nodes and spleen where B cells reside. Within these centers B cells replicate, mature and prepare to create antibodies.

An antigen on the surface of the virus that antibodies can attach to.

The characteristics that are representative of activated T cells.

This subset of T cells that aid in the production of antibodies by activating B cells.

An antigen is a part of a pathogen that stimulates an immune response. This may be a protein, lipid, or a carbohydrate.

B cells are immune cells that produce antibodies.

In molecular genetics when a gene is induced, it means the amount of mRNA transcripts from that gene is increased.

Elucidated is another way of saying explained or investigated.

Cytokines are proteins that are released by immune cells to activate the immune response in other cells.

Example: When a cell is infected with a virus, it can release the cytokine interferon to signal neighboring cells of an incoming viral attack. This allows the neighboring cells to increase production of anti-viral proteins.

Choline acetyltransferase is a protein that is responsible for the creation of acetylcholine.

Prototypic means the original model in which further knowledge is based off of.

Since acetylcholine was the first neurotransmitter discovered, its function/ behavior is what all other neurotransmitters are based off of.

Vasodilation in when blood vessels expand. This is an important response to viral infection because it allows immune cells to reach the site of infection.

Ablated in this context means that mice did not have vasodilation in response to viral infection.

IL-21 is a protein released by CD4 T cells that activates cytotoxic T cells and NK cells.

A CD8 positive T cell (referred to as a cytotoxic T cell) is responsible for killing intracellular pathogens, cancer cells and other damaged cells.

A CD4 positive T cell (referred to as a helper T cell) is a subset of T cells responsible for activating and directing different types of immune cells.

T cells, B cells and Natural Killer (NK) cells are immune cells that are referred to as lymphocytes.

A T cell is a type of immune cell responsible for directing the adaptive immune system's response to infection, allergy and cancer.

• note: think of the T cell as a general of an army.

A neurotransmitter is a molecule released by nerves to communicate with other nerves, muscles fibers, or organ systems.