attenuated virus as type of vaccine in this ppt how it made , how it work , adv , disadv. & examples

1. Attenuated vaccine

2. Contents
1. Definition
2. How it made
3. How it works
4. Advantages
5. Disadvantages
6. Examples

3. Attenuated vaccine
 derived from “wild,” or disease-causing, viruses or
bacteria that have been weakened under laboratory
conditions.
 Attenuated vaccine is strong enough to cause immune
response, but too weak to cause disease
 AVs stimulate an excellent immune response that is nearly
as good as compared to an infection with the wild-type
pathogen.
 Viruses are often attenuated (weakened) by growing them
in cells that they don’t normally grow in for many
generations. The viruses begin to evolve and adapt to these
new cells so that they are less able to live in their preferred
environment.

4.  Natural viruses need to reproduce thousands of times
during infection to cause disease. These weakened
viruses are only able to reproduce fewer than twenty
times.
 With such little reproduction, attenuated viruses are
not able to create nearly enough copies of
themselves to cause disease.
 However, enough viral particles are created to
create memory antibodies and keep the body from
getting the viral infection should it enter the body
naturally in the future.

5. How It made
 Preparation of LIVE but WEAKEN pathogens occur in
2 Steps:
 Step 1
Use the tissue culture to grow new viruses.
(Repeated Culture)
 Step 2
Fill the syringe with a strain of the virus that has
desirable characteristics.

6. Step 1
 You are about to create a live-attenuated vaccine,
which means that you need to alter a pathogen so
that it will still invade cells in the body and use those
cells to make many copies of itself, just as would any
other live virus.
 The altered virus must be similar enough to the
original virus to stimulate an immune response, but
not so similar that it brings on the disease itself.

To create a new strain of the virus, you'll need to let it
grow in a tissue culture.

7.  The tissue culture is an artificial growth medium for
the virus. You will intentionally make the environment
of the culture different than that of the natural human
environment. For this vaccine, you'll keep the culture
at a lower temperature.

8. Step 2
 Over time, the virus will evolve into strains that grow
better in the lower temperature. Strains that grow
especially well in this cooler environment are selected
and allowed to evolve into new strains.
 These strains are more likely to have a difficult time
growing in the warmer environment of the human
body. After many generations, a strain is selected that
grows slow enough in humans to allow the immune
system to eliminate it before it spreads.

9.  For example, the measles virus used as a vaccine today
was isolated from a child with measles disease in 1954.
Almost 10 years of serial passage using tissue culture
media was required to transform the wild virus into
attenuated vaccine virus.
 The attenuation of virus to create live attenuated
vaccines through reverse genetics technology, and
introduce targeted mutations, represents the most
advanced approach.

12. How it works
 A live attenuated vaccine contains a weakened form of
the infectious agent that cause the disease
 The infectious agent is alive, so cause an infection,
allowing the immune system to mount a complete
defense
 But the agent is attenuated, and doesn’t cause the host
to become sick

13.  the immune system produces T-lymphocytes and
antibodies.
 Once the imitation infection goes away, the body is left
with a supply of “memory” T-lymphocytes, as well as
B-lymphocytes that will remember how to fight that
disease in the future.
 the body takes a few weeks to produce T-lymphocytes
and B-lymphocytes after vaccination.

14.  Sometimes, after getting a vaccine, the imitation
infection can cause minor symptoms, such as fever.
Such minor symptoms are normal and should be
expected as the body builds immunity.

15. To produce an immune response, live attenuated
vaccines must replicate in the vaccinated person

17. Advantages
 A live attenuated vaccine is a method of delivering
weakened versions of a disease causing pathogen into
the human body, where it can induce the immune
system into preparing itself for any future encounters
with the real.
 Live vaccinations can usually immunize a person after
a single dose, and regular boosters aren’t needed (as is
the case with other types of vaccine). The MMR
vaccine( is an vaccine is an excellent example of an
effective live vaccine that only requires one or two
doses to achieve its effects.

18.  The MMR vaccine is an immunization vaccine against measles
, mumps, and rubella.
 It is estimated that 90% of the people receiving the MMR injection will
become immunized after the first dose, and a second dose is provided by
the NHS childhood immunization program to account for the remaining
10% of the population.
 Live, attenuated vaccines can also sometimes be delivered by alternative
routes. For example a polio vaccine( are used throughout the world to
combat poliomyelitis) can be delivered orally, reducing the need for
injections which many people might not be comfortable with.
 Finally live, attenuated vaccines often result in fewer side effects than
some alternative forms of vaccination like antibody vaccines.

19. Disadvantages
special storage
back mutation
side effects

20. special storage
Temperatures
time

23.  Vaccine Storage
 There are few immunization issues more important
than the appropriate storage and handling of vaccines.
 The success of efforts against vaccine-preventable
diseases is attributable in part to proper storage and
handling of vaccines.
 Vaccines exposed to temperatures outside the
recommended ranges can have reduced potency and
protection.
 Storage and handling errors can cost thousands
of dollars in wasted vaccine and revaccination.

25. Time
 Vaccines must be stored properly from the time they
are manufactured until they are administered.
 Proper maintenance of vaccines during transport is
known as the cold chain.
 A proper cold chain is a temperature-controlled
supply chain that includes all equipment and
procedures used in the transport and storage and
handling of vaccines from the time of manufacturer to
administration of the vaccine.

26. Temperatures
 Vaccines are fragile.
• They must be maintained at the temperatures recommended by vaccine
manufacturers and protected from light at every link in the cold chain.

Most live virus vaccines tolerate freezing temperatures, but deteriorate rapidly
after they are removed from storage.

Inactivated vaccines can be damaged by exposure to temperature
fluctuations (e.g., extreme heat or freezing temperatures).
 Potency can be adversely affected if vaccines are left out too long or exposed to
multiple temperature excursions (out-of-range temperatures) that can have a
cumulative negative effect.
 It is a good idea to post a sign on the front of the storage unit(s) indicating
which vaccines should be stored in the freezer and which
should be stored in the refrigerator.

28. Side-effects
 Some side-effects may be serious while others may
only be a mild inconvenience.
 Everyone's reaction to a medicine is different
 Measles Virus Live Attenuated/Mumps Virus Live
Attenuated/Rubella Virus Live Attenuated (Measles,
Mumps and Rubella vaccine (live) powder and solvent
for solution for injection 0.5ml vials)

29.  Very common: More than 1 in 10 people who have Measles virus live
attenuated/Mumps virus live attenuated/Rubella virus live attenuated:
• fever
 injection site problems such as redness, swelling or pain
 Common: More than 1 in 100 people who have Measles virus live
attenuated/Mumps virus live attenuated/Rubella virus live attenuated:
• infections including respiratory tract infection
• skin rash or rashes

30.  Uncommon: More than 1 in 1000 people who have Measles virus
live attenuated/Mumps virus live attenuated/Rubella virus live
attenuated
 abnormal crying
 Bronchitis
 cough
 diarrhoea
 difficulty sleeping
 ear or hearing problems
 eye or eyesight problems
 feeling nervous
 loss of appetite
 swelling of the salivary glands
 vomiting

31.  Rare: More than 1 in 10,000 people who have Measles virus
live attenuated/Mumps virus live attenuated/Rubella virus
live attenuated:
• convulsions
 Very rare: Fewer than 1 in 10,000 people who have Measles
virus live attenuated/Mumps virus live attenuated/Rubella
virus live attenuated:
• brain or central nervous system problems
 The frequency of these side-effects is unknown
• abnormal muscle movement
• arthritis
• joint pain
• thrombocytopenia

33. Mutation
 Mutation. This may lead to reversion to virulence (this is a major
disadvantage)
 One of the primary concerns for example, is the risk of reversion to a
more virulent strain of the virus or bacteria being vaccinated against.
 secondary mutation
 One or more of these will possess a mutation that enables it to infect
the new host.
 These mutations will spread, as the mutations allow the virus to grow
well in the new host; the result is a population that is significantly
different from the initial population, and thus will not grow well in the
original host when it is re-introduced (hence is "attenuated").
 This makes it easier for the host's immune system to eliminate the
agent and create the immunological memory cells which will likely
protect the patient if they are infected with a similar version of the
virus in "the wild".

35. Examples
 Measles virus
 Mumps virus
 Rubella virus
 Polio virus
 Yellow fever virus
 Tuberculosis bacterium
 (Chickenpox) vericella v.