EN
Influenza virus is the main etiological agent of respiratory diseases in horses. Equine influenza virus is represented by two different serotypes: H7N7 and H3N8. The H7N7 strain has not been isolated since 1980 and H3N8 circulates in equine population throughout most of the world. Inactivated and subunit vaccines are most commonly used in order to prevent infections. These vaccines, in contrast to natural infections, do not induce either cytotoxic lymphocytes T or mucosal antibodies, nor do they provide long-lasting immunity. The introduction of new types of vaccines has become necessary and the first group of new generation vaccines is those containing live viral strains. They may be produced by attenuation in low temperature or by reverse genetics. Viral vector vaccines may be included in this group of vaccines. The next group of new generation of vaccines consists of a DNA vaccine and an inactivated vaccine with new adjuvants.