8-Immunization and immune assay0-987654334567890-.ppt

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Natural immunities:
active (acquired from an infection and then recovering)
passive (antibodies donated by the mother to her child).
Artificial immunities
active (vaccinations with antigen, to stimulate an immune response)
passive (immune therapy with a serum containing antibodies).
Categories of acquired immunities

3. A knowledge of the immune system and its
responses to antigens has provided extremely
valuable biomedical applications in two major
areas:
(1)Use of antiserum and vaccination to provide artificial
protection against disease
(2)Diagnosis of disease through immunologic testing.
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4. The first attempts at passive immunization involved the
transfusion of horse serum containing antitoxins to prevent
tetanus and to treat patients exposed to diphtheria.
Immune serum globulin (ISG), sometimes called gamma
globulin, contains immunoglobulin extracted from the
pooled blood of at least 1,000 human donors.
It is a treatment of choice in preventing measles and
hepatitis A and in replacing antibodies in
immunodeficient patients.
Most forms of ISG are injected intramuscularly to
minimize adverse reactions, and the protection it provides
lasts 2 to 3 months.
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5. Specific immune globulin (SIG) serum obtain
from patients who are recovering and in a hyper
immune state after such infections as pertussis,
rabies, tetanus, chickenpox, and hepatitis B.
These globulins are preferable to ISG because they
contain higher titers of specific antibodies obtained
from a smaller pool of patients.
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When a human immune
globulin is not available,
antisera and antitoxins of
animal origin can be used.
Sera produced in horses
are available for diphtheria,
botulism, and spider and
snake bites

6. vaccination exposing a person to material that is
antigenic but not pathogenic.
The basic principle behind vaccination is to
stimulate a primary and secondary response, that
primes the immune system for future exposure to
a virulent pathogen.
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7. Principles of Vaccine Preparation
Effectiveness (have long-lasting effects in a few doses)
Ease in administration,
Safety,
mimic the natural protective response
Cost.
Most vaccine preparations contain one of the following antigenic
stimulants :
Killed whole cells or inactivated viruses.
live, attenuated cells or viruses.
antigenic components of cells or viruses.
Genetically engineered microbes or microbial antigens.
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8. Why killed vaccines often
require a larger dose and
more boosters to be
effective? Because the
microbe does not multiply
Killed or inactivated vaccines
Inactivation: cultivating the desired strain of a bacterium or virus
and treating them with formalin, radiation, heat, or some other
agent that does not destroy antigenicity.
Examples:
Bacterial vaccine (Typhoid fever).
Virus vaccine (Salk polio and influenza).

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9. Live, attenuated microbes.
Attenuation: is any process that substantially lessens the virulence
of viruses or bacteria.
It is usually achieved by modifying the growth conditions or
manipulating microbial genes in a way that eliminates virulence
factors.
Attenuation methods include:
Long-term cultivation,
growing at colder temperatures (cold mutants)
Passage of the microbe through unnatural hosts or tissue culture,
Removal of virulence genes.
Examples: Vaccines for measles, mumps, polio (Sabin), and rubella.
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10. The advantages of live vaccine are:
1.Viable microorganisms can multiply and produce
infection (but not disease) like the natural organism;
2.confer long-lasting protection.
3.require fewer doses than other types of vaccines
Disadvantages are:
1.require special storage facilities,
2.Can be transmitted to other people,
3.Can mutate back to a virulent strain
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11. A special type of vaccine is
the toxoid which
consists of a purified
bacterial exotoxin that
has been chemically
denatured such as
diphtheria and tetanus.
A cellular (subunit vaccines) vaccines.
If the exact antigenic determinants that stimulate immunity are known, it is
possible to produce a vaccine based on a selected component of a
microorganism. The antigen used in these vaccines may be taken from
cultures of the microbes, produced by rDNA technology, or synthesized
chemically.
Examples:
The capsules of the pneumococcus and meningococcus.
The protein surface of anthrax.
The surface proteins of hepatitis B virus.
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12. Currently, much attention is being focused on newer strategies:
Employ antigen synthesis: using plants to synthesize
microbial proteins, potentially leading to mass production of
edible vaccine antigens.
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Recombinant DNA (Trojan horse vaccine):
genetic material from a selected infectious agent is
inserted into a live carrier that multiplies and
expresses the foreign genes microbe that is
nonpathogenic (Vaccinia virus as carrier for AIDS,
herpes simplex 2, leprosy, and tuberculosis.)

14. Gene cloning technology: isolating the genes that encode
various microbial antigens, inserting them into plasmid
vectors, and cloning them in appropriate hosts (hepatitis B
rotavirus and Lyme disease, syphilis, Schistosoma, and
influenza).
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15. In this technique, DNA is inserted into a plasmid vector and inoculated
into a recipient to form of proteins. Because these proteins are foreign,
they will be recognized during immune surveillance and cause B and T
cells to be sensitized and form memory cells.
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16. The advantages:
These vaccines are very safe and only a small amount of the foreign antigen need be expressed to
produce effective immunity.
Vaccines for, hepatitis C, herpes simplex, influenza, tuberculosis, papilloma- virus, and malaria are
undergoing animal trials, most with encouraging results
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The antiidiotype vaccine
it is based on the principle that the antigen binding (variable)
region, or idiotype, of a given antibody (A) can be antigenic to
a genetically different recipient and can cause that recipient’s
immune system to produce antibodies specific for the variable
region on antibody. The purpose for making anti-idiotypic
antibodies is that they will display an identical configuration
as the desired antigen and can be used in vaccines.

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This method avoids administering a microbial antigen, thus
reducing the potential for dangerous side effects. Using
monoclonal antibodies, this approach has been used to mimic
the surface antigen of hepatitis B virus and Trypanosoma with
some success.

19. Easier to give.
More readily accepted.
Well tolerated.
Some vaccines require the addition of a special binding substance, or
adjuvant.
An adjuvant: is any compound that enhances immunogenicity and prolongs
antigen retention at the injection site. The adjuvant precipitates the antigen
and holds it in the tissues so that it will be released gradually (facilitates
contact with macrophages and lymphocytes).
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Most vaccines are injected by subcutaneous,
intramuscular, or intradermal routes. Oral
vaccines are available for only two diseases,
but they have some distinct advantages. An
oral dose of a vaccine can stimulate
protection (IgA) on the mucous membrane.
Oral vaccines are:

20. Common adjuvants are:
Alum (aluminum hydroxide salts),
Freund’s adjuvant (emulsion of mineral oil, water, and extracts of mycobacteria),
Beeswax.
The most common complication vacccines are
local reactions at the injection site, fever and allergies .
Relatively rare reactions (about 1 case out of 220,000 vaccinations) are:
1.panencephalitis (from measles vaccine),
2.back-mutation to a virulent strain (from polio vaccine),
3.disease due to contamination with dangerous viruses or chemicals,
4.neurological effects of unknown cause (from pertussis and swine flu
vaccines).
5.Some patients experience allergic reactions to the medium (eggs or tissue
culture) rather than to vaccine antigens.
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21. Most recently, the whole-cell pertussis vaccine was replaced by
the a cellular capsule (aP) form when it was associated with
adverse neurological effects.
The live oral rotavirus vaccine had to be withdrawn when
children experienced intestinal blockage.
Polio vaccine was switched from live, oral to inactivated when
too many cases of paralytic disease occurred from back-
mutated vaccine stocks.
certain vaccine preservatives (thimerosal) that are thought to
cause allergies and other potential side effects.
The greatest caution must be exercised in giving live vaccines to
immunocompromised or pregnant patients, the latter because
of possible risk to the fetus.
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