Introduction to virology

Viruses are the simplest infectious agents, and yet, as they parasitize our bodies, they can cause devastating disease. Viral diseases range from the common cold and diarrhea to life-threatening encephalitis, hemorrhagic fever, and smallpox. Several different viruses may cause a single disease, as determined by the tissue or organ that is affected, or one virus may cause a unique disease due to the nature of its interaction with the body. Ultimately, the nature of the disease caused by the virus is a function of the tissue that is infected, the nature of the virus, and the host immune response to the virus. Interestingly, each of these parameters is determined by the structure and mode of replication of the virus. This chapter introduces the basic viral structures and modes of replication, and presents the consequences of these properties for the different virus families. In many cases, knowing the structure of the virus allows prediction of many of the other properties of the virus. This introduction also includes a discussion of general mechanisms of viral pathogenesis and disease production, epidemiology, antiviral drugs, and viral detection before a synopsis of each of the virus families is presented. References to some recent reviews and other publications on virology by the author [1-4] are provided.