detail view of virosomes

1. VIROSOMES
Presented by-
Sushmita Gupta
M.Pharmacy
Industrial Pharmacy
Acharya & B.M. Reddy College of Pharmacy

2.  Introduction
 Structure of virosomes
 Mechanism of action
 Advantages
 Methods of preparation
 Characterization of virosomes
 Applications
 References
CONTENTS

3.  Virosomes can be defined as a drug or a vaccine delivery
mechanism consisting of unilamellar phospholipid ( either a
monolayer or bilayer) vesicle incorporating virus derived
proteins to allow the virosomes to fuse with the target cell.
 They are lipid based , synthetic vesicles consisting of viral surface
glycoproteins.
 They have a typical mean diameter of 150 nm.
 They protect the pharmaceutically active substance from
proteolytic degradation and low pH within endosomes allowing
their contents to remain intact when they reach the cytoplasm.
Introduction

4.  Virosomes are produced by dissolving the envelop of virus
by a detergent or short chain phospholipid followed by the
complete removal of the viral genetic material and non-
membranous protein.
 The viral membrane is reconstituted producing a virosome
containing the viral membrane protein and lipid after
removing the detergent or short chain phospholipid.
 Viral proteins confer to the virosome based vaccine
structural stability , homogeneity and immunological
properties.
Structure of virosomes

6.  It is an influenza virus.
 The envelop made up of influenza lipids constitute the
membrane and proteins called haemagglutinin (HA) and
neuraminidase (NA) are intercalated on it.
 The nucleocapsid and the genetic material of the source
virus is present inside the envelop.

7.  Virosomes act both as carrier and as adjuvant with
multifunctions during the induction of an immune
response.
 The carrier function comprises the positive effects of
embedding the antigen into a higher structure, the
virosome particle.
 The adjuvant function relates to the immune stimulating
properties of the virosomes and their components on the
immune system.
 It also suceeds in stimulating specific immunity without
causing non-specific inflammation.
Mechanism of action

9. Virosomal technology is approved by FDA for use in
humans and has higher safety profile.
 Virosomes are biodegradable, biocompatible and non-
toxic.
 There is no risk of disease transmission.
 No autoimmunogenity or anaphylaxis.
 It is broadly applicable to almost all important
drugs(anti-cancer, proteins, peptides, nucleic acid,
antibiotics , fungicides etc).
 It enables the drug delivery into the cytoplasm of the
target.
cont…1.
Advantages

10. * Promotes the fusion activity in the endolysosomal
pathway.
* Protects the drugs against degradation.
* Extended uptake, distribution and elimination of
drug in the body.
* It allows patient specific modular vaccine regime.
* The fully functional activity of virosome enables
receptor mediated uptake which leads to the
stimulation of both arms of the immune system
such as humoral and cellular immune response.

11.  Selection of virus
 Selection of antigen
 Reconstitution of virus
Method of preparation

12.  Virosomes are reconstituted viral envelop that can be
derived from different virus.
 Influenza virus envelop is mostly used for preparation
of virosomes but virosome can also be made from
sendai virus, epstein burr virus, HIV , herpes simplex
virus, newcastle disease virus.
Selection of virus

13.  Antigen is selected as per the requirements. Eg-
parasite, carcinogenic cell, bacterium or whole cell.
 Cell components such as DNA, RNA or plasmid can
also be used as antigen.
 This antigen is coupled with lipid anchor so antigen
will be ready to load on virosomes.
Selection of antigen

14. Reconstitution of virosome
 Due to solubilisation with detergent (octaglucoside, triton
x100, nonidert p-40) ,the internal viral protein and genetic
material will sediment.
 The detergent is later removed by different methods such
as dialysis and hydrophobic resins from supernatant.
 Viral matrix protein and nucleiocapsid is removed by
ultracentrifugation.
 Viral phospholipids(82%) and viral protein is recovered.
 The antigen which is already coupled to lipid anchor is mixed
with polymer or surfactant solution.
 This solution is processed with virosome carrier so that
antigen bound virosome is obtained.

16.  Protein detection
Virosome preparation should generally result in a relatively
uniform protein to lipid ratio. Sodium dodecyl sulphate poly 5
acrylamide gel electrophoresis can confirm the presence of
HA protein in the virosomes.
 Structure and size
Negative stain electron microscopy can be generally used to
determine the ultra structure and size of virosomes. The
staining solutions should be of neutral pH to avoid acid-
induced conformational changes of HA.
cont…
Characterisation of virosomes

17.  Fusion activity
Virosomes exhibit pH dependent membrane fusion activity
similar to native influenza virus. Virosomal fusion with
biological or artificial target membrane are visualised with a
fluorescent resonance energy transfer assay.

18.  Cancer treatment
Virosomes are used in the oncology field to carry peptide
corresponding to tumour associated antigen as in case of
peptide from parathyroid hormone related protein or from
recombinant protein.
 Gene delivery
Haemagglutinin, the membrane fusion protein of influenza
virus is known to mediate a low pH dependent fusion reaction
between the viral envelop and the limiting membrane of
endosomal cell compartment following cellular uptake of virus
particle by receptor mediated endocytosis.
cont…
Applications

19.  RNA/DNA delivery
Small interfering RNA encapsulated in virosomes are able to
down regulate the synthesis newly induced and constitutively
expressed proteins overcoming the lack of suitable delivery
methods for these molecules.
 Malarial therapy
Malarial vaccine containing virosome formulated anti-malarial
peptides shows a good tolerability and high specific immune
response in humans.

20.  General applications
 Blood substitute for haemoglobin.
 Artificial blood surrogates.
 Pharmaceutical pigments or dyes.
 Biological response modifiers.
 Radiopharmaceutical and radio diagnosis carriers.
 Drug /protein drug delivery vehicle.
 Drug solubilisation enhancers.
 In cosmetics and dermatology.
 Drug overdose treatment.
 Separation and extraction technique.
 Enzyme immobilisation.
 In fabrication of micro capsulated dosage form.
 Antifungal, antimicrobial and antiviral therapy.

21.  Gautham M, Pulak M, Krishnakumar KK. Journal of
pharmaceutical and scientific innovation. A novel
strategy for delivery of drugs and targetting.
 Babar et al., J Antivir Antiretrovir 2013. Virosomes-
Hybrid drug delivery system.
 Sharma R, Yasir M. Virosomes- A novel carrier for drug
delivery. Int. J for Pharm Tech Research. Oct-dec 2010,
vol.2, no.4 , pp 2327-39.
References

22. THANK YOU