Virosomes as drug delivery system

Virosomes as drug delivery system

Virosomes

Semi-synthetic complex derived from nucleic acid free viral particles. They are reconstituted viral coat, their infectious nucleocapsid is replaced by compound of choice ( antigen-drug-gene). To deliver them to target cells. So, used as vaccine virosomes, gene transfer, or drug delivery system

Virosomes as Cancer treatment

The antigen (has TAP) is encapsulated into the virosome ( virosome protects antigen from extracellular protease). In late endosomes (pH 5.5), the virosome fuse with the endosomal membranes, and thus before the fusion of endosomes with lysosomes containing protease. The antigen is delivered directly from endosomal vesicles to the cytosol of target cells, where it can follow the classical route of endogenous antigen presentation because the antigen is delivered into the cytosol in the form of an optimized peptide, one can suggest that it will easily enter the RE through tumor associated peptide (TAP).

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2-A virosomal immunization strategy against cervical cancer and pre-malignant cervical disease

Anovel synthetic vector for cancer treatment proposed from the evaluation of virosomes

The size of the synthetic vector composed from lipids or polymers is 50–100 nm in diameter. Some components are conjugated with PEG for long circulation. On the surface, cancer-targeting molecules and fusion proteins are attached

Fusion proteins, such as F protein of HVJ, increase the efficiency of drug delivery and also stimulate IL-6 production in DCs, which suppresses Treg cells and enhances anti-tumor immunity. Exogenous RNA should be contained inside the particle to stimulate cytokines and chemokines for the activation of CTL and NK cells and to up-regulate pro-apoptotic genes for cancer-specific apoptosis. To augment anti-tumor activities, therapeutic molecules such as anti-cancer agents, siRNA and plasmid DNA may also be incorporated[

3-Virosome-mediated delivery of tumor antigen to plasmocytoid dendritic cells (PDC)

Virosome structure

1-Intrinsic anti-tumor activities of virosomes

4-Tissue-targeting HVJ-E virosome

Applications of virosomes

1. Cancer treatment

2. Malaria therapy

3. Gene therapy

4. DNA/RNA delivering to cells

Virosomes enter cells through receptor mediated endocytosis after binding to sialic acid residues on the cell surface .

The fusion of virosomal membrane mediated by the viral spike agglutinine & established continuum between the virosome lumen & cell cytoplasm enable delivering of encapsulated compounds into the cytoplasm of cell (target cells), this mediated by acidic PH.

Administration of virosomes

By parentral routes :

IV

IM

SC

Advantages of virosomal technology :

Drug Delivery approaches

Bioactive drug compound can be entrapped in aqueous interior of virosome or in its lipid membrane for facilitated entery of compound into cells such as ( nucleic acid , gene, and protein )

1. Biodegradable, biocompatible, and non-toxic

2. No disease transmission risk

3. No auto-immunogenicity or anaphylaxis

4. Broadly applicable with most important drugs (anticancer, antibodies, fungicides )

5. Protect drug against degradation