Some epitopes are more immunogenic and are termed immunodominant because they always induce strong antibody responses.

Antibodies to epitopes on the outside of the virus often neutralise in-vitro and protect in-vivo because they prevent attachment.

Antibodies to epitopes on the inside of the virus do not neutralise. They are widely used to identify a particular virus in tissues e.g. rabies inclusions in a dog brain or FeLV in cat blood.

T cells bind to peptide derived from the manufacture of the surface or internal proteins of the virus. The peptides which are produced in highest quantity and also fit into the MHC grooves are the usual targets.