Colorized transmission electrone microscope picture with membrane proteins (red), viral membrande (white), lumen (brown) and ribonucleoproteins (purple). A virus with an envelope of the genus influenzavirus in a TEM-picture: Eight helical capsids are enclosed in a viral envelope (particle about 80-120 nm in diameter).
Influenza viruses belong to the familiy of the orthomyxoviridae (RNA-viruses) and cause the illness influenza ("real" flu).
Under the electron microscope influenza viruses are spherical or polymorph, eveloped, virus particles with a diameter of about 80-120 nm. The viral envelope contains different proteins and glycoproteins. The big glycoproteins protude as 10-14 nm long spikes from the virus surface. Hemagglutinin (H) and Neuraminidase (N) are glycoproteins.
The genome of almost all influenza viruses consists of eight RNA-segments with "negative sense/polarity" which contain the genetic information od the virus and code for several proteins. This segmentation of the genome is made resposible for the high genetic variability of the influenza viruses.
Transmission of influenza viruses can occur in three ways:
(Source: CDC/ Dr. Erskine. L. Palmer; Dr. M. L. Martin)
