INFLUENZA IMAGES

Influenza A particles showing the variety of forms the virus can take. The particles are surrounded by spikes consisting of haemagglutinin and neuraminidase proteins (purple) embedded in the viral membrane. The internal helical component appears as a compressed spring-like structure where the particle has been ruptured (centre top). This internal component carries the M protein, which

specifies the virus as type A or B. It is only type A, however, that undergoes the large and very rapid changes leading to new viral subtypes known as antigenic shift.CC BY NC ND R Dourmashkin/Wellcome Images

Influenza A

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Drawing of the 1918 Spanish influenza virus, showing congestion of vessels, infiltration of round cells and thickening of membrane.CC BY NC Wellcome Library, London

Original drawing of the 1918 Spanish flu virus

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Influenza B virus particles, surrounded by spikes consisting of haemagglutinin and neuraminidase proteins embedded in the viral membrane. Both A and B influenza types can cause the epidemic forms of the disease; flu vaccines offer protection to both strains of the virus. Influenza B does not undergo the large, rapid changes that type A does

but changes slowly by the process of antigenic drift.CC BY NC ND R Dourmashkin/Wellcome Images

Influenza B virus particles

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H1N1 influenza virus particles; surface proteins on the particles are shown in black.CC BY NIAID/Flickr

H1N1 influenza virus particles

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A model of the H1N1 virus, which causes ‘swine flu’. The name H1N1 refers to the types of haemagglutinin and neuraminidase proteins on the surface of the virus. There are roughly ten times as many haemagglutinin proteins (red) as neuraminidase (yellow). In the centre is the single-stranded viral RNA (purple).

CC BY NC ND Anna Tanczos/Wellcome Images

H1N1 virus

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Annotated image of the influenza virus:1. Haemagglutinin (H), the structure that enables the virus to bind to host cells.

2. M2, an ion channel.3. Neuraminidase (N), an enzyme that helps to release new virus particles from the cell.

Credit:Adapted from Sebastian Kaulitzki/iStockphoto

Annotated graphic of the H1N1 virus

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Influenza viruses (blue) attaching to the cells of the upper respiratory tract. Viruses floating in the air are breathed in and bind to the hair-like microvilli and cilia on the surface of the cells that line the trachea. They then enter the cells and start to proliferate, eventually causing the cells to die.

CC BY NC NDR Dourmashkin/Wellcome Images

Influenza viruses infecting cells

Influenza viruses being uncoated in a cell

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Influenza viruses (the dark particles around the upper surface of the endosome) in an infected cell. These viruses are in the process of being uncoated before replicating in the host cell.

CC BY NC ND R Dourmashkin/Wellcome Images

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