Vaccine delivery systems aim to improve vaccine efficacy. Lipid carriers like liposomes can encapsulate antigens and target uptake. Oral vaccines induce mucosal and systemic immunity but antigens face degradation; new live-attenuated and plant-derived oral vaccines show promise. Controlled release microparticles using biodegradable polymers like PLGA can provide single-dose vaccine delivery by controlling antigen release. Peptide and nucleic acid vaccines produce pathogen proteins endogenously but face challenges like rapid degradation; delivery systems and carriers aim to overcome these challenges.

1. VACCINE DELIVERY
BY
SAHITHI GADDE
DEPARTMENT OF PHARMACEUTICS
KVSR SIDDHARTHA COLLEGE OF
PHARMACEUTICAL SCIENCES
VIJAYAWADA-10

2. Contents…..
• About vaccines…
• Mechanism of uptake and transport of
antigens…
• Delivery systems used to promote uptake…
Lipid carrier systems
Oral immunization
Controlled release micro particles for vaccine
development
Single dose vaccine delivery systems using
biodegradable polymers..
• Peptide based and nucleic acid based vaccines…

3. History of vaccines……
VACCINE- from the Latin vacca (cow)
 The diary workers would never have the often
fatal disease smallpox because they already have
the cowpox

4. Jenner took the pus from the hand of a milkmaid with cow
pox, scratched it into the arm of an 8 yr old boy and six
weeks later inoculated (variolated) the boy with small pox,
he observed that boy did not catch smallpox.
History…….

5. Edward Jenner ( 1976)
The terms vaccine and vaccination are
derived from variolae vaccinae (small pox
of the cow), the term devised by Edward
Jenner to denote cow pox.
Louis Pasteur ( 1880)
The second generation of vaccines
was introduced in 1880s by Louis
Pasteur who developed vaccines for
chicken cholera and anthrax.
History ……

6. What are
vaccines…????
• A vaccine is a biological preparation that improves immunity
to a particular disease.
• A vaccine typically contains an agent that resembles a
disease-causing microorganism and is often made from
weakened or killed forms of the microbe, its toxins or one of
its surface proteins.
• The agent stimulates the body’s immune system to recognize
the agent as foreign, destroy it, and keep a record of it, so that
the immune system can more easily recognize and destroy any
of these microorganisms that it later encounters.
• Vaccines can be prophylactic ( to prevent or ameliorate the
effects of a future infection by any natural or wild pathogen),
or therapeutic ( vaccines against cancer).

7. Types of vaccines…
Vaccines are dead or inactivated organisms or
purified products derived from them. The
different types of vaccines are:
a) Traditional vaccines
b) Innovative vaccines

8. a) Traditional vaccines
1. Killed -
2. Live, attenuated –
3. Toxoid -

9. 4. Subunit vaccines- rather than introducing an
inactivated or attenuated micro-organism to an
immune system a fragment of it can create an immune
response

10. b) Innovative vaccines
1) Conjugate vaccines -
2) Recombinant vector vaccines (DNA)
vaccines)

11. 3) T-cell receptor peptide vaccines - they show the
modulation of cytokine production and improve cell
mediated immunity and are under development.
4) Valence
i. Monovalent (univalent) - used to immunize against single
antigen.
ii. Multivalent (polyvalent) - used to immunize against two or more
micro organisms.
5) Heterotypic – vaccines that are pathogens of other animals
that either do not cause disease or cause mild disease in the
organism being treated.

12. Mechanism of uptake and
transport of antigens……
or
how do vaccines work..??

13. Eliminated by:
Killing of infected cells by CTL that
use antigens generated by
ENDOGENOUS PROCESSING
Y
Eliminated by:
Antibodies and phagocyte
activation by T helper cells that use
antigens generated by
EXOGENOUS PROCESSING
Antigens generated by endogenous and exogenous antigen
processing activate different effector functions
ENDOGENOUS
PATHOGENS
EXOGENOUS
PATHOGENS

14. Stages of exogenous antigen processing
UPTAKE
Access of native antigens and pathogens to intracellular
pathways of degradation
DEGRADATION
Limited proteolysis of antigens to peptides
ANTIGEN-MHC COMPLEX FORMATION
Loading of peptides onto MHC molecules
ANTIGEN PRESENTATION
Transport and expression of peptide-MHC complexes on
the surface of cells for recognition by T cells

15. Uptake of exogenous antigens
Y
Pinocytosis
Phagocytosis
Membrane Ig
receptor mediated
uptake
Y
Complement receptor
mediated phagocytosis
Fc receptor mediated phagocytosis
Uptake mechanisms direct antigen into intracellular vesicles for
exogenous antigen processing

16. Endogenous antigen processing
UPTAKE
Antigens/pathogens already present in cell
DEGRADATION
Antigens synthesised in the cytoplasm undergo limited
proteolytic degradation in the cytoplasm.
ANTIGEN-MHC COMPLEX FORMATION
Loading of peptide antigens onto MHC class I molecules
is different to the loading of MHC class II molecules
PRESENTATION
Transport and expression of antigen-MHC complexes on
the surface of cells for recognition by T cells

17. ER membrane
Lumen of ER
Cytosol
Transporters associated with antigen processing
(TAP1 & 2)
Transporter has preference for >8 amino acid peptides with
hydrophobic C termini.
Peptide
Peptide
Peptide
Peptide
Peptide
Peptide
Peptide
Peptide
Peptide
Peptide
ER membrane
Lumen of ER
Cytosol Peptide
ATP-binding cassette
(ABC) domain
Hydrophobic
transmembrane
domain
Peptide antigens
from proteasome

18. Endoplasmic reticulum
Peptide
Cytoplasmic peptides are loaded onto the MHC molecule and the
structure becomes compact

19. Cell surface
peptides
of Ag
Antigens must be processed in order to be
recognised by T cells
YT
T cell
response
No T cell
response
No T cell
response
No T cell
response
No T cell
response
Soluble
native Ag
Cell surface
native Ag
Soluble
peptides
of Ag
Cell surface peptides of Ag
presented by cells that express
MHC antigens
ANTIGEN
PROCESSING

20. Immune System
Myeloid Cells
Granulocytic
Neutrophils
Basophils
Eosinophils
Monocytic
Macrophages
Kupffer cells
Dendritic cells
Lymphoid Cells
T cells
Helper cells
Suppressor cells
Cytotoxic cells
B cells
Plasma cells
Natural Killer
cells
How do vaccines work….

21. Response to vaccines…

22. Response to pathogens…

24. Are vaccines effective in all cases..??
The efficacy or performance of vaccine is dependant on a number
of factors:
 The disease itself
 The strain of vaccine
 Whether one kept to the timetable for vaccinations
 Some individuals are not responders to certain vaccines,
meaning that they do not generate antibodies even after being
vaccinated correctly
 Other factors such as ethnicity, age, or genetic pre
disposition.

25. Adverse effects
• Adverse effects if any are mild.
• The rate of side effect depends on the
vaccine in question.
• Some potential side effects include
Fever
Pain around the injection site
Muscle aches

26. Delivery systems used to promote
uptake…..
Absorption enhancers:
 The term absorption enhancer usually refers to an agent
whose function is to increase absorption by enhancing
membrane permeation, rather than increasing solubility, so
such agents are sometimes more specifically termed as
permeation enhancers.
 Absorption enhancers are functional excipients included in
formulations to improve the absorption of a
pharmacologically active drug.
Ex: skin permeation enhancers include non-ionic surfactants
which cause changes in the intracellular proteins of stratum
corneum and increase permeability by this mechanism.

27. Lipid carrier systems
 Liposome's are concentric bilayered vesicles in which
hydrophilic moieties are enclosed by a membranous lipid
bilayer mainly composed by natural or synthetic phospho-
lipids

28. Role of liposome's in delivering
vaccines.....
Liposome with antigens… Uptake of the liposome by the cell
membrane…..

30. Liposome's targeting to tumor cells

31.  Viruses, proteins, glyco proteins, nucleic acids,
carbohydrates and lipids can be entrapped and
targeted at cellular and sub cellular level.
 The development of polymerized liposome's which
have shown enhanced stability in the GIT also offers
potential for use in mucosal delivery.
 Liposomal vaccines based on viral membrane
proteins (virosomes) have been approved as products
in Europe for hepatitis A and influenza.

32. Virosomes….
A virosome is a drug or vaccine delivery
mechanism consisting of unilamellar phospholipid
membrane (either a mono- or bi-layer)
vesicle incorporating virus derived proteins to
allow the virosomes to fuse with target cells.

33. Oral immunization
 Most currently available vaccines are delivered by injection, which makes mass
immunization more costly and less safe, particularly in resource-poor developing
countries.
 Oral vaccines have several attractive features compared with parenteral vaccines,
but these are regarded historically as likely to be less effective, as vaccine antigens
undergo digestion in the GI tract prior to induction of an immune response.
 At present there are limited number of oral vaccines approved for human use, but
many more are in the late stages of clinical development.
 Due to the limited absorption from the intestinal tract and sensitivity to
degradation, oral vaccines composed of killed bacteria and viruses or antigens
isolated from infectious agents have not been successful.
 New, live-attenuated bacterial and viral or edible plant-derived vaccines, how ever,
have been recently introduced for this purpose.
 Furthermore, systemic immunization with vaccines composed of bacterial
polysaccharides chemically coupled to suitable protein carrier induces high levels
of IgG antibodies, which may provide immunity toward Salmonella typhi,
Shigella, and Escherichia coli.

34.  Orally delivered vaccines are processed and presented by
the digestive tract’s immune system, often referred to as the
gut-associated lymphoid tissue (GALT).
 The GALT is a complex system consisting of inductive sites
( where antigens are encountered and responses are
initiated) and effector sites ( where local immune response
occur) linked by a homing system, where by cells induced by
antigen in the GALT migrate to the circulation and,
subsequently colonize the mucosa.
 As a result, oral vaccination can induce immune responses
locally in the gut and at distant mucosal sites, as well as
systemic humoral and cellular immune responses.
 Oral vaccination typically generates a large amount of
secretary IgA, which plays a major role in mucosal defense.
How oral vaccines induce immune responses…

37. Controlled release micro particles for
vaccine development…
 PLGA( polylactide co-glycolic acid) is used as a
biodegradable micro particle for vaccine delivery due to the
abundance of data and information on its properties, uses and
role in on going studies.
 A particular interesting area is the use of the biodegradable
micro particles is to deliver DNA vaccines.
 These are the third generation vaccines, and are made up of a
small, circular piece of bacterial DNA ( called plasmid) that
has been genetically engineered to produce one or two specific
proteins ( antigens) from a pathogen

38. Preparation of PLGA micro particles………

39. Mechanism of release from microspheres is by
bulk erosion.
Factors that effect the release pattern are:
– Molecular weight of compound- greater the mol. Wt.
greater the bond, larger time to degrade.
– Chemical composition of co-polymer- release of the
peptide was prolonged when microspheres made of
copolymer containing higher proportion of
polylactide.
– Size of the microspheres- greater the particle size
longer the time to collapse, delays the release of
antigen.

40. Biodegradable nano particles

41. Malaria is a mosquito borne disease caused by a parasite.
Recent studies showed that upon encapsulating a subunit malarial antigen SPf66 in
PLGA- mixture microspheres resulted in high antibody levels in mice.
Recent trends……..
Microencapsulation of vaccine antigen using biodegradable polymers seems a
promising technology for needle-free targeted vaccination.

42. Single dose vaccine delivery systems
using bio degradable polymers……
 Single dose vaccines are given at a single contact point for
preventing 4 to 6 diseases.
 They would replace the need for a prime boost regimen,
consequently eliminating the repeated visits to the doctor’s for
mother’s and their children.
Disadvantage:
– Cost compared to the current vaccine.

43. Use of biodegradable polymers….
Biodegradable Polymers: it comprised of
monomers linked to one another through
functional groups and have unstable links in
the backbone.
These are broken down into biologically
acceptable molecules that are metabolized and
removed from the body via normal metabolic
pathways.

44. Types of biodegradable polymers:
The two types are:
• Natural biodegradable polymers
Ex: albumin, collagen, gelatin.
• Synthetic biodegradable polymers
Ex: aliphatic poly esters, poly anhydride, poly ortho
esters, pseudo poly amino acids etc.
Poly( lactide-o-glycolic acids) (PLGA) is most
commonly used for vaccine delivery i.e. for
preparation of microspheres.

45. Pre-filled syringes
Advantages :
Convenience
Affordability
Accuracy
Sterility
Safety

46. Preparation of pre-filled syringes
The steps include:
• Preparation of container and closure assembly
of pre-filled syringes - mainly used are glass
and plastic.
• Filling process in pre-filled syringes - bubble-
free filling
• Sterilization of pre-filled syringes - by
autoclave and ionizing radiations mainly by
ionizing radiations that to gamma radiation

48. Peptide based vaccines….
A peptide vaccine is a type of subunit vaccine
in which a peptide of the original pathogen is
used to immunize an organism.
These types of vaccines are usually rapidly
degraded once injected into the body, unless
they are bound to a carrier molecule such as a
fusion protein.

49. Delivery of peptides…
Antibodies usually bind to surface proteins of the pathogen or
proteins generated after the disruption of the pathogen.
Binding of antibodies to these proteins will stimulate an immune
response.
Therefore proteins can be use to stimulate an immune response.

51. Peptide based cancer vaccines

52. Nucleic acid based vaccines……
 The use of nucleic acid-based vaccines is a novel approach to
immunization that elicits immune responses similar to those
induced by live, attenuated vaccines
 Administration of nucleic acid vaccines results in the endogenous
generation of viral proteins with native confirmation,
glucosylation profiles, and other post-translational
modifications that mimic antigen produced during natural viral
infection.
 Nucleic acid vaccines have been shown to elicit both antibody and
cytotoxic T-lymphocytes responses to diverse protein antigens.
 ADVANTAGES:
 Simplicity of the vector
 The ease of delivery
 Duration of expression

53.  Nucleic acid vaccines are still experimental, and have been
applied to a number of viral, bacterial and parasitic models of
disease as well as to several tumor models.
Types of nucleic acids:
1) DNA ( deoxy ribose nucleic acid) – contains the genetic
instructions used in the development and functioning of all known
living organisms (with the exception of RNA viruses). These
segments carrying the genetic information are called genes.
2) RNA ( ribo nucleic acid) – it functions in converting genetic
information from genes into the amino acid sequences of protein.
 Direct DNA delivery in vivo can be utilized for the production of
proteins as well as for the induction of specific cellular and
humoral immune response against a large number of viral
pathogens ( influenza, hepatitis b, HIV, etc.).

54. DNA vaccines…
 DNA vaccination is a technique for protecting an organism
against disease by injecting it with genetically engineered
DNA to produce an immunological response.
 These are the third generation vaccines, and are made up of a
small, circular piece of bacterial DNA ( called plasmid) that
has been genetically engineered to produce one or two specific
proteins ( antigens) from a pathogen.
 In 1996, trails involving T-cell lymphoma, influenza and
herpes simplex virus were started.

55. How DNA vaccine is made…
Viral gene
Expression plasmid
Plasmid with foreign gene
Transform into bacterial cell
Plasmid
DNA

56. Plasmid DNA get amplified
Plasmid DNA purified
Ready to use

57. Methods of delivery
Method of Delivery Formulation of
DNA
Target Tissue Amount of DNA
Injection (hypodermic needle) Aqueous solution in saline
IM (skeletal); ID; (IV,
subcutaneous and
intraperitoneal with variable
success)
Large amounts (approximately
100-200 μg)
Gene Gun DNA-coated gold beads
ED (abdominal skin); vaginal
mucosa; surgically exposed
muscle and other organs
Small amounts (as little as
16 ng)
Pneumatic (Jet) Injection Aqueous solution ED Very high (as much as 300 μg)
Topical application Aqueous solution Ocular; intravaginal Small amounts (up to 100 μg)
Cytofectin-mediated
Liposomes (cationic);
microspheres; recombinant
adenovirus vectors;
attenuated Shigella vector;
aerosolized
cationic lipid formulations
IM; IV (to transfect tissues
systemically); intraperitoneal;
oral immunization to the
intestinal mucosa; nasal/lung
mucosal membranes
variable

58. Gene gun delivery Pneumatic jet injection
Hypodermic needle injection

59. How DNA vaccines work….

61. DNA vaccine against cancer..

62. RNA vaccines….
 Recent studies have demonstrated that mRNA
formulated in liposome's and administered sub-
cutaneously or intravenously, effectively generated
antibody and CTL’s directed against the encoded
protein.
 However, the difficulty and expenses of large scale
RNA production and the relative instability of
mRNA compared to DNA might render RNA
vaccines an impractical means of immunization.

64. Conclusion…
Although various vaccines have been
successfully developed for several diseases,
research is still in progress to develop vaccines
for life threatening diseases like cancer, AIDS
etc..