Introduction to virology

Summary

History of viruses

The existence of viruses was first suspected in the nineteenth century when it was shown that filtered extract of infective material passed through filters small enough to stop all known bacteria could still be infectious, and hence the ‘virus’ (Latin for poisonous liquid) concept was first introduced. However, viral diseases such as smallpox and poliomyelitis had been known to affect mankind since many centuries before this.

Subsequent to the discovery of viruses, the next major step in elucidating their role in human disease was the invention of the electron microscope, followed by cell culture and now molecular diagnostic techniques to detect the presence of viruses in infected material. Many new viruses have been discovered in the past two to three decades, but it was the discovery of human immunodeficiency virus (HIV) (the virus responsible for acquired immunodeficiency syndrome (AIDS)) in 1983 and the explosion of the AIDS epidemic that brought clinical virology to the forefront as a significant specialty. Millions of dollars have been spent by pharmaceutical companies in discovering drugs to treat AIDS; a by-product has been that our understanding of virus replication and pathogenesis has improved substantially and this has resulted in new antiviral drugs becoming available to treat other viral infections.

The availability of rapid and sensitive molecular diagnostic techniques and effective antiviral drug therapy means that patients can now be treated in real time.