Antibody A specialized protein of the immune system that binds to proteins or portions of proteins from invaders.  Once bound the antibodies activate the immune system in various ways.
Antigen Any material (usually proteins) that stimulates a response from the immune system.  Viral strains have unique antigens.
Antigenic Drift Changes in antigenic properties of organisms due to genetic drift
Cell Mediated Immunity An acquired specific immune response primarily based on cellular activity. Capable of killing cells infected with viruses
Genetic Drift Changes in the genetic makeup of populations of organisms due point mutations in the genome
Humeral Immunity An acquired specific immune response primarily based on antibody activity.  Capable of neutralizing virions
Innate Immunity A non specific immune response – first response of immune system
Killed Virus Virons that have been rendered dysfunctional usually by chemical means.  Not capable of infecting cells but can stimulate humeral immunity via surface antigens
Lipid Fat – in the context of cells and viruses a bi-layered membrane composed of two layers of lipid molecules that have proteins either embedded or on the surface
Modified Live Virons that have been altered by genetic selection so that they infect cells but do not cause disease.  Stimulate humeral and cell mediated immunity.
Mucosal Immunity Optimized humeral and cell mediated immunity that occurs when the antigen has been presented to the host via a mucosal surface ie nasal passages
Negative sense RNA that must be converted to positive sense before being processed by ribosomes to produce proteins
Neutralize Ability of antibodies to bind and agglutinate virions in a laboratory setting
Recombinant Virons that have been genetically altered to express antigens from another type of virus
RNA Ribonucleic acid – a form of genetic material that can encode for proteins
Selection Pressure A pressure that drives genetic change in populations of organisms by favoring certain genotypes
Serotype Group of virions that are neutralized by antibodies contained within a specific reference sera
Serum Liquid component of blood that contains proteins including antibodies
Strain Form of virus that is genetically and antigenically different from other viruses in the same serotype.  The more different a viral strains is from the strain that produced immunity the more likely the strain will infect a host animal
Virion The inert but infectious form of a virus that exists outside of host cells
Virus An infectious element that is inert outside of a host organism and relies on host cell metabolic processes to replicate

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Terms and Definitions