This third edition of the Encyclopedia of Virology is being published nine years after the second edition, a period which has
seen enormous growth both in our understanding of virology and in our recognition of the viruses themselves, many of
which were unknown when the second edition was prepared. Considering viruses affecting human hosts alone, the
worldwide epidemic of severe acute respiratory syndrome (SARS), caused by a previously unknown coronavirus, led to
the discovery of other human coronaviruses such as HKU1 and NL63. As many as seven chapters are devoted to the
AIDS epidemic and to human immunodeficiency viruses. In addition, the development of new molecular technologies
led to the discovery of viruses with no obvious disease associations, such as torque-teno virus (one of the most ubiquitous
viruses in the human population), human bocavirus, human metapneumovirus, and three new human polyomaviruses.
Other new developments of importance to human virology have included the introduction of a virulent strain ofWest
Nile virus from Israel to North America in 1999. Since that time the virus has become established in mosquito, bird and
horse populations throughout the USA, the Caribbean and Mexico as well as the southern regions of Canada.
As in the two previous editions, we have tried to include information about all known species of virus infecting
bacteria, fungi, invertebrates, plants and vertebrates, as well as descriptions of related topics in virology such as antiviral
drug development, cell- and antibody-mediated immunity, vaccine development, electron microscopy and molecular
methods for virus characterization and identification. Many chapters are devoted to the considerable economic
importance of virus diseases of cereals, legumes, vegetable crops, fruit trees and ornamentals, and new approaches to
control these diseases are reviewed.
General issues such as the origin, evolution and phylogeny of viruses are also discussed as well as the history of the
different groups of viruses.