Wednesday, December 8, 2021
- Advertisement -

The influenza virus

- Advertisement -

Influenza or virus influenza (also called influenza or Myxovirusinfluenzae) is a virus RNA of the family Orthomyxoviridae. Its eight molecules RNAare found in a capsid protein, inside an envelope. The influenza virus is transmitted by air.

Influenza viruses belong to the Orthomyxoviridae family and the genus Influenzavirus, of which there are three types A, B and C. Type A and B viruses are responsible for annual influenza epidemics, but the only type A viruses are the origin of influenza pandemics. The type C virus appears to be linked to sporadic cases.

Type A viruses are the most common and the most virulent; several subtypes can be distinguished on the basis of their surface antigens, hemagglutinin (H1 to H18) and neuraminidase (N1 to N11). So that gives 144 possible combinations, but for seasonal flu, the viruses involved boil down to H1, H2, H3 and N1 or N2 responsible for the annual flu. In birds, all subtypes exist with varying pathogenicity. We remember the H5N1 avian influenza virus, which had spread in the form of an epizootic, transmitted in rare cases to humans but with often fatal consequences.

Features of the influenza virus

The virus influenza carries a genome negative polarity single-stranded RNA, composed of 8 segments of 900 to 2,300 bases. The entire genome reaches 13,500 bases. This genome codes for 11 proteins. The viral particle contains the 8 RNA, packaged in viral proteins. The whole is surrounded in a layer of matrix proteins and enveloped in a cell-like membrane, forming a viral particle 80 to 120 nanometers in diameter.

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

Reusable Protection Mask

Face Protection Anti-Saliva Anti-Splash Facial Protection for Men and Women

Diversity of influenza viruses

There are three types of influenza viruses, called A, B and C. Viruses A and B are responsible for epidemics of influenza seasonal. Type A viruses are named after the H and N proteins present, ranging from H1 to H18 and N1 to N11. Thus, the subtypes found in human infections can be H1N1 or H3N2 viruses. The B viruses present in humans are the B Yamagata and B Victoria lineages. The reservoirs of influenza A circulate in various animals, birds and mammals (pigs, etc.), while the B and C viruses 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 by two viruses.

Infection with the influenza virus

The virus attaches itself to receptors in cells in the respiratory system through hemagglutinin. After endocytosis virus, RNAs are transported to the cell nucleus for transcription of messenger RNAs to take place. The replication of viral RNA and the translation of proteins ultimately make it possible to manufacture new viral particles which can be excreted to colonize other cells.

- Advertisement -

Related Articles


Please enter your comment!
Please enter your name here

Stay Connected

- Advertisement -

Latest Articles