This is a basic presentation for understanding the basics of DNA vaccines, their modes of administration, and action.

1. BY-
AAYUSHI RAMBIA
M.Sc. SEM I
REG NO. 18308001
PONDICHERRY UNIVERSITY

2.  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
"remember" it, so that the immune system can more
easily recognize and destroy any of these
microorganisms that it later encounters.
(Definition as adopted from WHO)

3. 1796
• British physician , Edward Jenner used the cowpox virus (vaccinia) to confer protection
against smallpox, a related virus, in humans.
1870
1885
• Louis Pasteur created the first live attenuated bacterial vaccine against chicken cholera.
• He created the first live attenuated viral vaccine against rabies.
1890-
1904
• Von Behring and Kitasato Shibasaburo successfully tested vaccines for diphtheria and
tetanus
1914
• Tetanus vaccine becomes available.
1920-
1940
• Vaccines against tuberculosis , diphtheria and yellow fever , influenza and whooping cough
created.
1955-
1960
• Salk and Sabin created two different types of vaccines against polio myelitis.

4. (Adapted from Nature Reviews
Microbiology volume9, pages889–893 (2011)

5.  Recombinant DNA vaccines or simply DNA vaccines are
plasmid containing the DNA sequence encoding the
antigen(s) against which an immune response is sought,
and relies on the in situ production of the target antigen.
 Upon the injection of the DNA vaccines , the DNA is
taken up by the cells and the encoded protein antigen is
expressed , leading to both a humoral anitbody response
and a cell mediated immune response.
 These belong to the third generation of vaccines .
 The use of DNA as a vaccine started with the work of Jon
Wolff who injected DNA plasmids to produce a protein
response in mice.

6. (Adapted from
www.mdpi.com/journal/vaccines/special_issues/DNA-
vaccines)

7.  DNA vaccines are composed of bacterial plasmids.
 Expression plasmids used in DNA-based vaccination
normally contain two units:
1) The antigen expression unit composed of
promoter/enhancer sequences, followed by antigen-
encoding and polyadenylation sequences and
2) the production unit composed of bacterial sequences
necessary for plasmid amplification and selection .
 The construction of bacterial plasmids with vaccine
inserts is accomplished using recombinant DNA
technology.

8.  Once constructed, the vaccine plasmid is transformed
into bacteria, where bacterial growth produces multiple
plasmid copies.
 The plasmid DNA is then purified from the bacteria, by
separating the circular plasmid from the much larger
bacterial DNA and other bacterial impurities.
 This purified DNA acts as the vaccine.

9. ANTIGENIC GENE
PLASMID VECTOR
RECOMBINANT VECTOR

10. STEPS THEREAFTER
(ADAPTED FROM NPTEL)

11.  The major approaches involved in administration of DNA
vaccines are :-
1) Injection of DNA vaccine in saline, using a standard
hypodermic needle. Injection in saline is normally
conducted intramuscularly (IM) in skeletal muscle,
or intradermally (ID), delivering DNA to extracellular
spaces. This can be assisted by electroporation by
temporarily damaging muscle fibres with myotoxins
such as bupivacaine; or by using hypertonic solutions of
saline or sucrose.
Through this method large amounts of DNA
approximately 100-200 µg can be delivered .

12. 2) Gene gun method involves the injection of plasmid DNA
(pDNA) that has been adsorbed onto gold or tungsten
micro particles into the target cells using compressed
helium as an accelerant.
Usually administered to ED (abdominal skin) , vaginal
mucosa or surgically exposed muscle and other organs.
Through this method small amounts of DNA
approximately 16 ng can be delivered.
The method sometimes causes burning sensation and in
order to avoid this nowadays low pressure gene guns are
used instead of gold coated DNA vaccines.

13. 3) Another method includes the administration through
pneumatic jet injections ED (abdominal skin). It helps
deliver large amounts approximately 300 µg .
4) Aerosol instillation of naked DNA
on mucosal surfaces, such as the nasal and lung mucosa
and topical administration of pDNA to the eye. It helps
deliver small amounts of DNA approximately upto 100
µg.

14.  By two major pathways :-
1)Endogenous
Antigenic Protein is presented by cell in which it is
produced
Antigenic
Protein
Antigenic
Peptides
Plasmid
DNA
Nucleus
mRNA
MHC-I

15. Helper T-cell
Memory T- cells
Plasma T-cell

16. 2) Exogenous
Antigenic Protein is formed in one cell but presented by
different cell.
Antigenic Protein come
outside

17. Antigen Presenting Cell
Antigenic Peptides
T- Helper Cell
Cytokines
Activated B-Cell
Memory B-Cell
Plasma B-Cell
Memory
Antibodies
MHC-II

18.  Vaccination with no risk for infection.
 Antigen presentation by both MHC class I and class II
molecules.
 Immune response focused only on antigen of interest.
 Stability of vaccine for storage and shipping
 Cost-effectiveness.
 Long-term persistence of immunogen
ADVANTAGES OF DNA VACCINES

19.  Limited to protein immunogens
 Risk of affecting genes controlling cell growth
 Possibility of inducing antibody production against DNA
 Possibility of tolerance to the antigen (protein) produced
 Plasmid used is resistance to antibiotics for selection. It
may raise the resistance to same antibiotic in the host
 Over – expression may cause acute inflamatory
response.

20. There are currently 43 clinical trials evaluating DNA
vaccines for viral and non-viral diseases listed in
the clinicaltrials.gov database. The majority (62%) of
these trials are investigating vaccines for HIV (33%) or
cancers (29%). Almost half (38%) of cancer vaccines
currently being investigated are targeting melanoma. The
remaining 38% of enrolling or active clinical trials are
investigating vaccines for influenza, hepatitis B and C,
HPV, and malaria.

21. From: Clinical Applications of DNA Vaccines: Current Progress . Published
by Oxford University Press on behalf of the Infectious Diseases Society of
America

22.  With the advent of DNA vaccines there came a possibility for
treatment of incurable diseases such HIV ,Hepatitis and
Cancer.
 Despite remarkable progress in the field of DNA vaccine
research since its discovery in the early 1990s, the formal
acceptance of this novel technology as a new modality of
human vaccines depends on the successful demonstration of
its safety and efficacy in advanced clinical trials.
 Although clinical trials conducted so far have provided
overwhelming evidence that DNA vaccines are well tolerated
and have an excellent safety profile, the early designs of DNA
vaccines failed to demonstrate sufficient immunogenicity in
humans. However, studies conducted over the last few years
have led to promising results, particularly when DNA vaccines
were used in combination with other forms of vaccines.

23.  Immunology by Kuby 4th Edition
 Immunology by Kuby 6th Edition
 Tang DC, DeVit M, Johnston SA. (1992)“Genetic
immunization is a
simple method for eliciting an immune response”.
Nature; 356:152-4
 https://www.tandfonline.com/doi/full/10.1586/14760584.7.
2.175
 Clinical Infectious Diseases, Volume 53, Issue 3, 1
August 2011, Pages 296–
302,https://doi.org/10.1093/cid/cir334
 www.nptel.com
 https://www.nature.com/articles/nrg2432
 https://www.nature.com/articles/gt201467
 Google images