9Infection and Immunity

In all ages, "infection" is a serious menace to humanity. It was not until the 19th century that many of the diseases threatening our existence were caused by minuscule and mostly unicellular organisms. The discovery of the defense system against these organisms that is inherent in our bodies, namely immunity, stemmed from the development of the smallpox vaccination by Edward Jenner more than 200 years earlier. Prompted by this discovery, the mechanisms and functions of immunity had gradually been revealed, which eventually led to the establishment of the system of immunology. Many of the important findings in the field of medical biology in the 20th century have originated from the studies of immunology. Based on the knowledge of immunology, "monoclonal antibodies" were invented in the 1970s, which were then put to practical use as medical products at the turn of the 20th century. Consequently, diseases that had been deemed refractory by then became curable. No one could turn away from the significance of the fact that a number of human lives are being saved by vaccines and antibiotics. In this chapter, we will discuss "infection" and "immunity" from the perspective of biology to learn their essence.

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