This illustration from the CDC is a 3-D graphical representation of an influenza virion's structure. Influenza viruses are members of the Orthomyxoviridae family
, according to Encyclopedia Britannica, meaning their virions measure between 80 and 120 nanometers in diameter. Each virion contains hemagglutinin and neuraminidase antigens
, substances that cause our bodies to produce antibodies. The amount of each antigen determines the strain of the virus, which is where the H#N# naming structure comes from.