Virosomes in vaccine development: induction of cytotoxic T lymphocyte activity with virosome-encapsulated protein antigens.

Virosomes are reconstituted viral envelopes which lack the genetic material but retain the cell entry and membrane fusion characteristics of the virus they are derived from. Thus, influenza virosomes are taken up by cells via receptor-mediated endocytosis, which directs the particles to the endosomal cell compartment. Subsequently, the virosomal membrane fuses with the endosomal membrane induced by the mildly acidic pH within the endosomes.