State two characteristics shared by all viruses that can be seen in Fig. 5.1.
Neuraminidase removes sections of the host cell receptors that haemagglutinin binds to. This enables newly formed viruses to escape from host cells. Drugs have been developed that target neuraminidase. These drugs stop viruses leaving host cells. Suggest and explain how these drugs work to stop viruses leaving cells.
The human immune system makes antibodies in response to antigens such as neuraminidase and haemagglutinin. Outline the steps in an immune response that lead to antibody production against an antigen such as haemagglutinin.
Researchers are developing ways to produce antibodies so that artificial passive immunity can be given against influenza. Suggest the advantages and disadvantages of artificial passive immunity.
State two routes by which mammals can gain natural passive immunity to infectious diseases, such as influenza.