ANNUAL REPORT - Pevion Biotech AG

Ultrastructure of virosomes
Virosomes are spherical, unilamellar vesicles with a mean diameter of 150
nm. Essentially, virosomes represent reconstituted empty influenza virus
envelopes devoid of the nucleocapsid
including the genetic material of the source
virus. Virosomes are not able to replicate but
are pure fusion-active vesicles. They function
as both carrier platforms and adjuvants. In
contrast to liposomes, virosomes contain
functional viral envelope glycoproteins:
influenza virus hemagglutinin (HA) and
neuraminidase (NA) intercalated in the
phospholipid bilayer membrane. The unique
properties of virosomes partially relate to the
presence of these glycoproteins. They not
only confer structural stability and
homogeneity to virosome formulations, but
they significantly contribute to the
immunological properties of virosomes, which
are clearly distinct from other liposomal and
proteoliposomal carrier systems. These
proteins enable the virosome membranes to
fuse with cells of the immune system and thus
deliver their contents – the specific antigens –
directly to their target cells, eliciting a specific first-class immune response
even with weak-immunogenic antigens. Once they have delivered the
antigens, the virosomes are completely metabolized, whereas the
conventional adjuvant aluminum stays in the body. Thus virosomes are an
efficient and safe carrier and adjuvant system.
PeviPRO TM
PeviPRO TM is Pevion Biotech’s proprietary virosome carrier platform for the
development of antigen-specific prophylactic vaccines. Vaccines based on
PeviPRO TM generate high quality humoral immune responses and longlasting
protection, even with weak immunogens (for instance peptide
antigens). A main focus in Pevion Biotech’s own developments is the
PeviPROTM-based malaria vaccine, which completed clinical Phase I in Q2
2005.
PeviTER TM
Hemagglutinin
Neuraminidase
Phosphatidylcholine
Phosphatidylethanolamine
Figure 2: Ultrastructure of
virosomes
PeviTER TM is Pevion Biotech’s proprietary virosome carrier platform for the
development of T-cell antigen specific therapeutic vaccines against chronic
infectious diseases as well as other diseases including cancer. Vaccines
based on PeviTER TM generate a highly specific cellular immune response.
Pevion Biotech’s hepatitis C (HCV) vaccine uses the PeviTER TM approach by
encapsulating T-cell epitopes into virosomes and exposing them to the
immune system via the MHC class I/II pathway.
PeviPHAR
PeviPHAR is Pevion Biotech’s proprietary technology platform for drug
antisense and DNA delivery. Using specific receptors/ligands or
antigens/antibodies interactions, the virosomes will be targeted to specific
cells. Drugs, encapsulated into virosomes, will mainly be delivered to the
targeted cells, which will reduce the amount of the drug used and will also
diminish the toxic effects. A main focus is the site-specific delivery of
cytostatics in cancer therapy.
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