Influenza virus

The influenza virus (Myxovirus influenzae) belongs to the Orthomyxoviridaefamily and Influenza virusgenus.

Features of the influenza virus

The influenza virus has a single strand negative polarity RNA genome composed of 8 segments containing 900 to 2,300 bases. The whole genome contains 13,500 bases. The genome codes for 11 proteins.

The viral particle contains the 8 RNA segments, encapsulated in viral proteins. These are all surrounded by a protein matrix layer and enveloped in a cell membrane forming a viral particle 80 to 120 nanometres in diameter. Two viral proteins are anchored in the envelope and determine the viral type: haemagluttinin (H) and neuraminidase (N). There are 16 types of haemagluttinin and 9 types of neuraminidase.

There are strains of influenza A, B and C, all of which infect human beings although they also infect other animals.

Influenza virus and influenza

The virus attaches to respiratory system cell receptors via haemagluttinin. After the virus has been endocytosed, the RNAs are transported towards the cell nucleus where transcription of the messenger RNA takes place. Replication of viral RNA and protein translation ultimately results in the production of new viral particles that can be excreted to colonise other cells.