Influenza virus cutaway showing internal structure #4

Cutaway model of an influenza virus particle showing internal structures. Superficially you can see the spikes of Haemagglutinin (red) and Neuraminidase (squarish and yellow. These spikes pass through the greenish viral envelope to dock with the underlying matrix (M) proteins shown in purple. Inside the matrix shell you can glimpse the dark yellow cord-like ribonucleoproteins that house the viral genome. Flu viruses have eight of these cord-like RNPs. This segmented genome can get jumbled up during viral construction. This allows different strains to easily form from existing types if they happen to infect the same cell at the same time. Flu occurs in seasonal epidemics and periodically as major pandemics.