Influenza A virus subtype H1N1
In virology, influenza A virus subtype H1N1 (A/H1N1) is a subtype of influenza A virus. Major outbreaks of H1N1 strains in humans include the 1918 Spanish flu pandemic, the 1977 Russian flu pandemic and the 2009 swine flu pandemic. It is an orthomyxovirus that contains the glycoproteins hemagglutinin (H) and neuraminidase (N), antigens whose subtypes are used to classify the strains of the virus as H1N1, H1N2 etc. Hemagglutinin causes red blood cells to clump together and binds the virus to the infected cell. Neuraminidase is a type of glycoside hydrolase enzyme which helps to move the virus particles through the infected cell and assist in budding from the host cells.
Influenza A virus subtype H1N1
Soldiers march in front of the Pomona College Carnegie Library during the Spanish flu pandemic in 1918, all garbed in uniforms and face masks.
Influenza A virus (IAV) is a pathogen that causes the flu in birds and some mammals, including humans. It is an RNA virus whose subtypes have been isolated from wild birds. Occasionally, it is transmitted from wild to domestic birds, and this may cause severe disease, outbreaks, or human influenza pandemics.
Influenza A virus
A transmission electron micrograph (TEM) of the reconstructed 1918 pandemic influenza virus. The bottom structure represents membrane debris from the cells used to amplify the virus. Pictured are the 'elliptical' particles representing the smallest particles produced by influenza virus. Purification techniques often deform the particles without proper fixation protocols, leading to 'spherical' appearance. Filamentous or intermediate sized particles simply extend along the long axis on the opposite side of the genome segments.
Genetic evolution of human and swine influenza viruses, 1918–2009