What do the 'H' and 'N' in H1N1 mean?

Ever wondered what the H's and N's in H1N1, H5N1, H2N2, H3N2 mean?

H stands for hemagglutinin whilst N stands for neuraminidase.

What do they do?

Neuraminidase binds to cell membranes of the host respiratory and allows the virus to enter into the host cell and infect it.

Hemagglutinin breaks the glycosidic linkages between the virus and the host cell, allowing the virus to move on and infect other cells.