Transcript VACCINES - Rovira i Virgili University

VACCINES
What They Are How They Work
Topics in nanobiotechnology
Ph.D. Student: Aleksandra Różek
What Is a Vaccine?
Traditional vaccines contain either parts of microbes
or whole microbes that have been killed or weakened so that
they don’t cause the disease.
- take advantage of the body’s to learn how to
eliminate almost any disease causing germ, or microbe,
that attacks it.
Immune system takes > 1 week to learn how to fight off an
unfamiliar microbe.
Stronger microbes can spread through the body faster than
the immune system can fend them off.
Vaccine Benefits
Naturally acquired immunity – immunity produced by
antibodies passed from mother to fetus (passive), or by the body’s own
antibody and cellular immune response to a disease causing organism
(active).
Artificially acquired immunity – immunity provided by
vaccines, as opposed to naturally acquired immunity, which is acquired
from exposure to a disease-causing organism.
Herd immunity – the resistance to a particular disease gained
by a community when a critical number of people are vaccinated
against that disease.
How Vaccines Work?
Immune system – a collection of specialized cells and organs that protect the body
against infectious diseases.
Lymphocytes: T Cells & B Cells
Macrophages – large and versatile immune cells that devour and
kill invading microbes and other intruders.
- stimulate other immune cells by presenting them with small pieces
of the invaders.
Lymphocytes - white blood cells that are central to the immune system’s
response to foreign microbes.
B Cells – white blood cells crucial to the immune defenses.
They come from bone marrow and develop into blood cells
called plasma cells, which are the source of antibodies.
T Cells – white blood cells that direct or participate in
immune defenses.
Memory Cells and natural immunity
After body eliminated the disease some of the B cells and T
cells are converted into memory cells.
Memory B cells can quickly divide into plasma cells and make
more antibody if needed.
Memory T cells can divide and grow into disease-fighting army.
Different Types of Vaccines
Live, attenuated vaccines
A vaccine made from microbes
that have been weakened in the
laboratory so that they can’t cause
disease.
Inactivated or „killed” vaccines
A vaccine made from a whole viruses or bacteria
that has been inactivated with chemicals or heat.
Toxoid vaccine
A vaccine containing a toxoid, used to protect
against toxins produced by certain bacteria.
Subunit vaccines
A vaccine that uses one or more components
of a disease – causing organism, rather than
the whole, to stimulate an immune response.
Disease:
Measles, mumps, rubella, polio
(Sabin vaccine), yellow fever
Disease:
Cholera, flu, hepatitis A, Japanese
encephalitis, plague, polio (Salk Vaccine), rabies
Disease:
Diphtheria, tetanus
Disease:
Hepatitis B, pertussis, pneumonia caused by
Streptococcus pneumoniae
Different Types of Vaccines
Conjugate vaccines
A vaccine in which proteins that are easily recognizable
to the immune system are linked to the molecules that
form the outer coat of disease – causing bacteria to
promote an immune response. Conjugate vaccines are
designed primarily for very young children because their
immune systems can’t recognize the outer coats of certain
bacteria.
DNA vaccines
A vaccine that uses a microbe’s genetic material,
rather than the whole organism or its parts, to stimulate
an immune response.
Recombinat vector vaccines
Vaccines that use modified viruses or bacteria to deliver
genes that code for microbial antigens to cells of the body.
Disease:
Haemophilus influenzae type B, pneumonia
Caused by Streptococcus pneumoniae
Disease:
In clinical testing
Disease:
In clinical testing
Advantages
Disadvantages
1
Produce a strong immune response
Often give livelong immunity with one or two doses
2
Safer and more stable than live vaccines
Don’t require refrigeration: more easily stored and
transported
Teaches the immune system to fight off bacterial
toxins
Targeted to very specific parts of the microbe
Remote possibility that the live microbe could mutate
back to a virulent form
Must be refrigerated to stay potent
Produce a weaker immune response than live vaccines
Usually require additional doses, or booster shots
3
4
5
6
7
Fewer antigens, so lower chance of adverse reactions
Allow infant immune systems to recognize certain
bacteria
Produce a strong antibody and cellular immune
response
Relatively easy and inexpensive to produce
Closely mimic a natural infection, stimulating a
strong immune response
When developing a new vaccine, identifying the best
antigens can be difficult and time consuming
Still in expertimental stages
Still in expertimental stages