Download SLIDE 4 Live vaccines

Vaccines
SLIDE 1 Edward Jenner discovered the process of vaccination, when he found that injection with
cowpox protected against smallpox. His method of immunization via vaccination ushered in the new
science of immunology. After observing cases of cowpox and smallpox for a quarter century, Jenner
took a step that could have branded him a criminal as easily as a hero. On May 14, 1796, he removed
the fluid from a cowpox lesion from dairymaid Sarah Nelmes, and inoculated James Phipps, an eightyear-old boy, who soon came down with cowpox. Six weeks later, he inoculated the boy with smallpox.
The boy remained healthy. Jenner had proved his theory. He called his method vaccination, using the
Latin word vacca, meaning cow, and vaccinia, meaning cowpox. The publication of Jenner's An
Inquiry into the Causes and Effects of the Variolae Vaccinae set off an enthusiastic demand for
vaccination throughout Europe. Within 18 months, the number of deaths from smallpox had dropped
by two-thirds in England after 12,000 people were vaccinated. By 1800, over 100,000 people had been
vaccinated worldwide. As the demand for the vaccine rapidly increased, Jenner discovered that he
could take lymph from a smallpox pustule and dry it in a glass tube for use up to three months later.
The vaccine could then be transported.
SLIDE 2 Passive immunization is used when exposure to pathogen has already occurred and there
is not enough time to induce active protective immunity, or prophylactically in children with inherited
immune deficiencies or undergoing cancer chemotherapy (which suppresses the immune system).
Passive immunization involves administration of specific antibody which has been produced in a
human or animal in response to vaccination or environmental exposure to the pathogen. Active
immunization Active immunization entails the introduction of a foreign molecule into the body,
which causes the body itself to generate immunity against the target. This immunity comes from the T
cells and the B cells with their antibodies
SLIDE 3 Inactivated vaccines contain particles (usually viruses). These have been grown for the
purpose. They have been killed, using formaldehye or by other means (e.g. heat). But the virus still
looks intact; the immune system can develop antigens against it.
SLIDE 4 Live vaccines - attenuated (weakend) viruses 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, however some are bacterial in nature. They typically provoke more durable
immunological responses and are the preferred type for healthy adults. Examples include the viral
diseases yellow fever, measles, rubella, and mumps.
SLIDE 5, 6 Recombinant vaccines are those in which genes for desired antigens are inserted into
a vector, usually a virus that has a very low virulence. The vector expressing the antigen may be used as
the vaccine, or the antigen may be purified and injected as a subunit vaccine. Advantages of
recombinant vaccines are that the vector can be chosen to be not only safe but also easy to grow and
store, reducing production cost. Antigens which do not elicit protective immunity or which elicit
damaging responses can be eliminated from the vaccine, and proteins expressed on a virus, even if it is
not the usual pathogen, are more likely to have their native conformation. Disadvantages of
recombinant vaccines are their cost to develop, since the genes for the desired antigens must be
located, cloned, and expressed efficiently in the new vector. The only recombinant vaccine currently in
use in humans is the Hepatitis B Virus (HBV) vaccine, which is a recombinant subunit vaccine.
Hepatitis B surface antigen is produced from a gene transfected into yeast cells and purified for
injection as a subunit vaccine. This is much safer than using attenuated HBV.
BASIC REQUIREMENT
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EXTRA REQUIREMENTS
SLIDE 7 Subunit vaccines see the slide
SLIDE 8 DNA vaccines are the newest vaccines and are still experimental, although to date they
seem to be very effective and their safety record is good. Like recombinant vaccines, genes for the
desired antigens are located and cloned. In the case of DNA vaccines, however, the DNA is injected
into the muscle of the animal being vaccinated, usually with a "gene gun" that uses compressed gas to
blow the DNA into the muscle cells. Some muscle cells express the pathogen DNA to stimulate the
immune system. Both humoral and cellular immunity have been induced by DNA vaccines.
SLIDE 9 Subunit vaccines rather than introducing an inactivated or attenuated microorganism to
an immune system (which would constitute a "whole-agent" vaccine), a fragment of it can create an
immune response.
SLIDE 10 Toxoid vaccines are made from inactivated toxic compounds that cause illness rather than
the micro-organism. Examples of toxoid-based vaccines include tetanus and diphtheria.
SLIDE 11 Anti-Aids vaccine see the slide.
SLIDE 12 Edible vaccines Research into edible vaccines is still at a very early stage and scientists
have a long way to go in proving their efficacy. Getting plants to express adequate amounts of the
vaccine, is proving challenging enough, let alone translating that into an appropriate immunological
response in people.
SLIDE 13 Vaccination with mosquitous
BASIC REQUIREMENT
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