A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease.Vaccine contains certain agents that not only resembles a disease-causing microorganism but it also stimulates body’s immune system recognize the foreign agents.Vaccines can be prophylactic or therapeutic. The administration of vaccines is called vaccination. British physician Edward Jenner, who in 1796 used the cowpox virus (Latin variola vaccinia) to confer protection against smallpox. In 1885 the French microbiologist Louis Pasteur and Emile Roux developed the first vaccine against rabies. There are several types of vaccines like Whole-Organism vaccine, recombinant vaccine,dna vaccine, multivalent subunit vaccines etc.

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RESHMA R
BIOINFORMATICS

2. VACCINE
 Biological preparation that improves immunity to a
particular disease.
 Contains certain agents that not only resembles a disease-
causing microorganism but it also stimulates body’s immune
system recognize the foreign agents.
HISTORY
 British physician Edward Jenner, who in 1796 used the
cowpox virus (Latin variola vaccinia) to confer protection
against smallpox.
 In 1885 the French microbiologist Louis Pasteur and Emile
Roux developed the first vaccine against rabies.

3.  Whole-Organism Vaccines
 Killed
 Attenuated
 Purified Macromolecules as Vaccines
 Toxoids
 Capsular polysaccharides
 Recombinant microbial antigens/Surface antigens
 Recombinant vaccine
 DNA vaccine
 Multivalent Subunit Vaccines

4. Killed/ Inactivated
 Some vaccines contain killed, but previously
virulent, microorganisms that have been
destroyed with chemicals, heat, radioactivity
or antibiotics.
Attenuated
 Some vaccines contain live, attenuated
microorganisms. Many of these are live
viruses that have been cultivated under
conditions that disable their virulent
properties, or which use closely related but
less dangerous organisms to produce a broad
immune response.

5. Inactivated/exotoxins/Toxoid
 Toxoids are vaccines which consist of exotoxins
that have been inactivated,either by heat or
chemicals. These vaccines are intended to
build immunity against the toxins, but not
necessarily the bacteria that produce the
toxins.
 Some examples are botulinum antitoxin and
diphtheria antitoxin.

7. Capsular polysaccharides
 The virulence of some pathogenic bacteria
depends primarily on the antiphagocytic
properties of their hydrophilic polysaccharide
capsule.
 Coating of the capsule with antibodies and or
complement greatly increases the ability of
macrophages and neutrophils to phagocytose
such pathogens.
 The current vaccine for Streptococcus
pneumoniae, which causes pneumococcal
pneumonia, consists of 23 antigenically different
capsular polysaccharides

8. Recombinant microbial antigens/Surface antigens
 The gene encoding any immunogenic protein
can be cloned and expressed in bacterial,
yeast, or mammalian cells using recombinant
DNA technology.
 The first such recombinant antigen vaccine
approved for human use is the hepatitis B
vaccine. This vaccine was developed by
cloning the gene for the major surface
antigen of hepatitis B virus (HBsAg) and
expressing it in yeast cells

9.  The recombinant vaccine is developed
through the recombinant DNA technology.
 These Vaccines are produced by the insertion
of genetic material which encoding the
antigen that stimulates an immune response.
 Plasmid DNA is used as vaccine which is
propagated in bacteria like E.Coli and they
get isolated and purified in to the vaccine.

11.  DNA vaccines are the vaccines which contain
DNA that codes for specific
proteins(antigens)from a pathogens.
 The DNA is injected into cells.
 Uses the DNA to synthesize the protein.
 Because these proteins are recognized as
foreign.when they are processed by the host
cell and displayed on their surface the
immunesystem is alerted.
 Which then triggers immune responses.

13. 1. Generation of the antigen
 The first step in order to produce a vaccine is generating
the antigen that will trigger the immune response. For
this purpose the pathogen’s proteins or DNA need to be
grown and harvested using the following mechanisms:
 Viruses are grown on primary cells such as cells from
chicken embryos or using fertilised eggs (e.g. influenza
vaccine) or cell lines that reproduce repeatedly (e.g.
hepatitis A)
 Bacteria are grown in bioreactors which are devices that
use a particular growth medium that optimises the
production of the antigens
 Recombinant proteins derived from the pathogen can be
generated either in yeast, bacteria or cell cultures.

14. 2. Release and isolation of the antigen
 The aim of this second step is to release as much
virus or bacteria as possible. To achieve this, the
antigen will be separated from the cells and
isolated from the proteins and other parts of the
growth medium that are still present.
3. Purification
 In a third step the antigen will need to be
purified in order to produce a high purity/quality
product.This will be accomplished using
different techniques for protein purification. For
this purpose several separation steps will be
carried out using the differences in for instance
protein size, physico-chemical properties,
binding affinity or biological activity.

15.  4. Addition of other components
 The fourth step may include the addition of an
adjuvant, which is a material that enhances the
recipient’s immune response to a
supplied antigen. The vaccine is then formulated
by adding stabilizers to prolong the storage life
or preservatives to allow multi-dose vials to be
used safely as needed. Due to potential
incompatibilities and interactions between
antigens and other ingredients, combination
vaccines will be more challenging to develop.
Finally, all components that constitute the final
vaccine are combined and mixed uniformly in a
single vial or syringe.

17.  Vaccine development is a complex and time-
consuming process that differs from the
development of conventional drugs.
 Vaccine clinical trials focus on demonstrating
prevention of a disease which implies that a higher
number of subjects will be required than for
traditional drug trials.
 Before a vaccine is licensed and brought to the
market, it undergoes a long and rigorous process of
research, followed by many years of testing.
 On average, the period for vaccine development is
12 to 15 years.

18. 1. Pre-Clinical Trials
 The first step to identifying a vaccine
candidate is the pre-clinical development
stage which goal is determining a vaccine’s
ultimate safety profile.
 During this stage the researchers will
carefully select the antigen and appropriate
technologies and both in vitro and in
vivo tests will be performed.
 The information collected from these studies
will be vital to begin safe clinical trials.

19. 2. Phase I clinical trials
 Phase I trials involve a small number of healthy
volunteers (20-50).
 The researchers will test the candidate vaccine for
the first time in humans in order to evaluate its
safety, determine a safe dosage range, and identify
vaccine-related side effects.
 This is achieved by comparing the vaccine with a
control or an inactive substance called placebo (e.g.
saline solution).
 Phase I trials can also provide initial data on the dose
and the time needed between vaccinations that will
lead to an optimal immune response.
 This first phase of the clinical trials lasts 12 to 18
months.

20. 3. Phase II clinical trials
 If the candidate vaccine presents optimal results
in phase I, it will then undergo Phase II trials
during which the candidate vaccine is
administered to a larger group of people (100-300)
to further evaluate its safety and immunogenicity.
 This phase will explore more deeply the right dose
and administration schedule and can last 2 or
more years.

21. 4. Phase III clinical trials
 The most promising vaccine candidates move
into Phase III enrolling 3,000 to 50,000
subjects.
 The goal of this phase is to conduct a large-
scale safety and efficacy study in the relevant
patient population to which the vaccine is
aimed.
 Moreover during this phase concomitant
administration with other vaccines will be
tested.
 Phase III clinical trials can last 3 to 5 years.

22. 5. Phase IV or Pharmacovigilance
 Once a vaccine has been marketed,
pharmacovigilance activities take place in order
to carry on a strict safety supervision of the
vaccines and detect, assess, understand, prevent
and communicate any adverse events following
immunisation, or of any other vaccine- or
immunisation-related issues.
 Long-term follow-up trials are often conducted to
provide evidence that the protection offered by
the vaccine is long-lasting

23.  Foreign invaders such as bacteria or viruses
enter the body by vaccine.
 lymphocytes respond by producing antibodies
 These antibodies fight the invader known as an
antigen and protect against further infection.
 After the threat has passed, many of the
antibodies will break down, but immune cells
called memory cells remain in the body.
 When the body encounters that antigen again,
the memory cells produce antibodies fast and
strike down the invader before it's too late.

24.  Vaccines also work on a community level.
Some people can't be vaccinated, either
because they are too young, or because their
immune systems are too weak, according to
the CDC. But if everyone around them is
vaccinated, unvaccinated people are
protected by something called herd immunity

25.  Vaccines have long been used to combat
infectious disease, however the last decade has
witnessed a revolution in the approach to
vaccine design and development.
 No longer is there a need to rely on the
laborious classical methods such as attenuation
or killing the pathogen.
 Now sophisticated technologies such as
genomics, proteomics, functional genomics, and
synthetic chemistry can be used for the rational
identification of antigens, the synthesis of
complex glycans, the generation of engineered
carrier proteins, and much more.

26.  The new techniques enabled heterologous
large-scale production of single proteins from
pathogens and their modification in order to
optimize proteins for vaccine use (e.g., by
detoxification of undesirable catalytic
activity).

27.  Firstly, genomic sciences gave birth to the field
of reverse vaccinology, which has enabled the
rapid computational identification of potential
vaccine antigens.
 Secondly, major advances in structural biology,
experimental epitope mapping, and
computational epitope prediction have yielded
molecular insights into the immunogenic
determinants defining protective antigens,
enabling their rational optimization.
 Thirdly, and most recently, computational
approaches have been used to convert this
wealth of structural and immunological
information into the design of improved vaccine
antigens.

28.  Vaccines are the most effective and economic
public health tools for control of infectious
disease.
 However, vaccine development faces a number
of challenges, such as overcoming the limited
effectiveness of a number of vaccines, the need
for frequent vaccine reformulation, as well as a
complete lack of vaccines for some diseases.
 A central goal of vaccination is to generate long
lasting and broadly protective immunity against
target pathogens, but this goal is hampered by
the variability of both the target pathogens and
the human immune system .