State how the structure of a virosome differs from that of a virus.
Explain how the structure of the virosome shown in Fig. 4.1 indicates that the centre of the virosome is aqueous.
The glycoproteins haemagglutinin and neuraminidase occur in the influenza virus and in the virosomes used in a vaccine against the influenza virus. Haemagglutinin attaches to a receptor in the cell surface membrane of phagocytes. Suggest why haemagglutinin is included in virosomes used in the influenza vaccine.
Mutations have led to different strains of the influenza virus. Each strain contains the enzyme neuraminidase. Neuraminidase enables the virus to exit host cells after replication has taken place. In every strain of the influenza virus, the primary structure of the active site of the neuraminidase enzyme stays the same. Suggest why the primary structure of the active site of neuraminidase stays unchanged in each strain of the influenza virus.