Definition | Influenza virus – Influenza virus – Myxovirus influenzae

Influenza virus model, or influenza virus, with neuraminidase (in green) and hemagglutinin (in blue) on the surface. © Sanofi Pasteur, Flickr, CC by-nc-nd 2.0

The virus influenza or virus influenza (also called influenzavirus or Myxovirus influenzae), is a virus ARN of the family of Orthomyxoviridae. Its eight molecules of RNA are found in a capsid protein, inside an envelope. The influenza virus is transmitted by air.

The envelope of viruses contains two kinds of proteins:hemagglutinin (H), which allows the attachment of the virion to the cell, and the neuraminidase (N), used for the detachment of buds during the formation of viral particles. Neuraminidase is also used for the lysis of mucus which has antiviral properties.

Diversity of influenza viruses

There are three types of influenza viruses, called A, B and C. Viruses A and B are responsible for flu epidemics seasonal. Type A viruses are named according to the H and N proteins present, ranging from H1 to H18 and from N1 to N11. Thus, the subtypes found in human infections can be the H1N1 or H3N2 viruses. The B viruses present in humans are the B / Yamagata and B / Victoria lineages. The tanks of the influenza A circulate among different animals, birds and mammals (pig …), while viruses B and C are mainly present in humans.

The variability of the virus is due to mutations, but also to reassortments and exchanges genetic between strains when the same cell is infected with two viruses.

Infection with influenza virus or influenza virus

The virus attaches to receptors in the respiratory system cells through hemagglutinin. After'endocytosis of the virus, the RNAs are taken to the cell nucleus so that the transcription messenger RNAs take place. The replication viral RNA and protein translation ultimately makes it possible to make new viral particles that can be excreted to colonize other cells.