The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

influenza virus

Any of a group of orthomyxoviruses that cause influenza, including at least three serotypes: Influenzavirus A , Influenzavirus B , and Influenzavirus C . Antigenic variants are classified on the basis of their surface antigens (hemagglutinin and neuraminidase) as H1N1, H2N2, etc. Serotype A viruses are subject to major antigenic changes (antigenic shifts) as well as minor gradual antigenic changes (antigenic drift) and cause the major pandemics. Serotype B viruses appear to undergo only antigenic drift and cause more localized epidemics. Serotype C viruses appear to be antigenically stable and cause only sporadic disease.