Influenza antigens can also be presented in the form of virosomes or can be expressed in a recombinant host (e.g., in an insect cell line using a baculovirus vector) and used in purified form (ref. 15). The invention can be used with any of these types of vaccine, but will typically be used with inactivated vaccines.
Influenza antigens can also be presented in the form of virosomes (ref. 22) (nucleic acid free viral-like liposomal particles), as in the INFLEXAL V™ and INVAVAC™ products.