Influenza viruses are about 100 nm in diameter, their outer membrane being the lipid bilayer membrane (elementary cell membrane). On the outer side of the membrane there are glycoproteins, which make the virus stick to the host cell membrane and make it difficult to be recognized by the antibodies. The main glycoprotein here is called Hemagglutinin. It has the shape of a spike, protruding perpendicularly from the viral outer membrane Outer part of this spike searches for the appropriate sugar chains on the host cell membrane and so adheres to the host cell. After the contact is established, the attack on the cell is triggered.
