The recently raised awareness of the threat of a new influenza pandemic has stimulated the interest in the detection of influenza A viruses in the secretions of a wide variety of birds and mammals. Influenza A viruses are subtyped conventionally according to the characteristics of the external glycoproteins, haemagglutinin (HA) and neuraminidase (NA). All 16 HA and 9 NA subtypes have been isolated from aquatic birds that are believed to be a natural host and reservoir for influenza viruses. Poultry, specifically chickens and turkeys, are not considered to be a normal host for the virus, although transmission from wild birds to poultry occurs routinely. Although most HA subtypes have been found in poultry, particular emphasis is placed on the H5 and H7 HA subtypes of avian influenza virus because only these subtypes are known to cause highly pathogenic avian influenza (HPAI) in poultry. Recently developed molecular methods enable fast, accurate and reliable approach to identify influenza virus and its subtypes.Svijest o prijetnji nove pandemije influence potaknula je zanimanje za dokaz virusa influence A u sekretima različitih vrsta ptica i sisavaca. Virusi influence A uobičajeno se tipiziraju na osnovi osobina njihovih površinskih glikoproteina, hemaglutinina (HA) i neuraminidaze (NA). Svih 16 HA i devet NA podtipova izdvojeno je iz vodenih ptica koje su prirodni domaćin i rezervoar virusa influence. Perad, posebice kokoši i pure, ne smatra se uobičajenim domaćinom virusa iako se virus redovito s divljih ptica prenosi na perad. Premda su mnogi HA podtipovi izdvojeni iz peradi, posebna pozornost pridaje se podtipovima H5 i H7 virusa influence ptica, jer samo oni pripadaju visoko patogenim sojevima za perad. Nedavno razvijene molekularne metode omogućuju brzu, točnu i pouzdanu identifikaciju virusa influence i njegovih podtipova
