immune system the system in the body that works to ward off infection and disease

pathogen s any disease-producing agent, especially a virus, bacterium, or other microorganism

antibody any of numerous Y -shaped protein molecules produced by B cells as a primary immune defense

white blood cells colorless cells in the blood that help combat infection

vaccine preparation of a weakened or killed pathogen, such as a bacterium or virus, that stimulates immune cells to recognize and attack it

hiv (aids virus) the Human Immunodeficiency Virus (HIV) is the virus that causes AIDS (Auto Immune Deficiency Syndrome)