Stock Photo - Virus H1N1, responsible for the deadly pandemy of Spanish flu in 1918 colorized TEM. succeded in rebuilding this virus from an avian influenza transmissible between human beings. His study will permit to understand better the modes of transmission of the virus H5N1 of the current avian influenza virus. Spanish flu virus, as all Influenza A viruses, is a pleiomorphic virus, which means that it can present under different forms according to the conditions. The virus H1N1 can present under a spherical or filamentous aspect. Spanish flu virus H1N1 Influenzavirus A Influenzavirus Orthomyxoviridae RNA Virus Virus. This transmission electron micrograph TEM of an ultra_thin specimen revealed some of the ultrastructural morphologic features seen in 1918 influenza virus virions. The prominent surface projections on the virions are composed of either the hemagglutinin, or neuraminidase type of glycoproteins. Composed of what looked like dots or tubules, was a dense envelope known as a «capsid», which surrounded each virion’s nucleic acid constituents. What is Influenza also called Flu The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent this illness is by getting a flu vaccination each fall. Every year in the United States, on average: _ 5 to 20 of the population gets the flu, _ more than 200,000 people are hospitalized from flu complications, and, _ about 36,000 people die from flu. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications.