Introduction to the Principles of Immunology

This chapter discusses how the human immune system combats viruses, either by spontaneously eliminating infections or by becoming stimulated via vaccination to prevent viral diseases. The proteins in viruses and bacteria that trigger an immune response are called antigens or immunogens, and the result of a satisfactory immune response to these antigens is immunity—long-term protection from repeated disease caused by a specific type of virus or bacteria. Similarly, a vaccine primes the immune response by programming it to anticipate and resist future pathogens like those in that particular vaccine. The immune system has evolved to deal with enormous numbers and varieties of every conceivable foreign antigen. However, the immune system must discriminate between foreign antigens, such as viral proteins, that are non-self and those antigens that are self, one’s own proteins (i.e., hormones such as insulin and cell proteins that make up muscle or nerve cells). Ultimately, the success of this system defines an organism’s capacity for survival.