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Vaccines Dr. Mehul Sheta Vaccines Dr. Mehul Sheta

Vaccines Dr. Mehul Sheta - PowerPoint Presentation

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Vaccines Dr. Mehul Sheta - PPT Presentation

Immunizations Two artificial methods to make an individual immune to a disease Active immunization administration of a vaccine response Passive immunization Individual acquires immunity through the transfer of antibodies formed by an immune individual or animal ID: 779551

vaccine vaccines attenuated disease vaccines vaccine disease attenuated stimulate immunity microbes immunization problems virulence active response immune modified mild

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Presentation Transcript

Slide1

Vaccines

Dr. Mehul Sheta

Slide2

Immunizations

Two artificial methods to make an individual immune to a disease

Active immunization-

administration of a vaccine response

Passive immunization-

Individual acquires immunity through the transfer of antibodies formed by an immune individual or animal

Slide3

History of Immunization

The Chinese - disease -

variolation

risk of death

Edward Jenner - cowpox- vaccination

mild disease

Louis Pasteur developed a vaccine against

Pasteurella

multocida

Transferring protective antibodies

Slide4

Vaccination Problems

Socioeconomic and political problems

Inability to develop effective vaccines for some pathogens

Vaccine-associated risks discourage investment in developing new vaccines

Slide5

Vaccine Types

Three general types of vaccines:

Attenuated (live)

Killed (inactivated)

Toxoid

Slide6

Attenuated Vaccines

Uses pathogens that are active but have reduced virulence so they don’t cause disease

Attenuation is the process of reducing virulence

Viruses often attenuated by raising them in tissue culture cells for which they aren’t adapted until they lose the ability to produce disease

Bacteria can be made

avirulent

by culturing under unusual conditions or through genetic manipulation

Slide7

Attenuated Vaccines

Can result in mild infections but no disease

Contain replicating microbes that can stimulate a strong immune response due to the large number of antigen molecules

Vaccinated individuals can infect those around them, providing herd immunity

Slide8

Problems with Attenuated Vaccines

Attenuated microbes may retain enough virulence to cause disease, especially in

immuno

-suppressed individuals

Pregnant women should not receive live vaccines due to the risk of the modified pathogen crossing the placenta

Modified viruses may occasionally revert to wild type or mutate to a virulent form

Slide9

Inactivated Vaccines

Can be either whole agent vaccines produced with

deactivated but whole microbes, or subunit vaccines

safer than live vaccines

When microbes are killed must not alter the antigens responsible for stimulating protective immunity

Formaldehyde is commonly used to inactivate microbes

Slide10

Problems with Inactivated Vaccines

Do not stimulate herd immunity

Whole agent vaccines may stimulate a

inflammatory

response due to non antigenic portions of the microbe

Antigenically

weak since the microbes don’t reproduce and don’t provide many antigenic molecules to stimulate the immune response

Slide11

Administration in high or multiple doses, or

The incorporation of an adjuvant, can make the vaccine more effective

Adjuvants

are substances that increase the

antigenicity

of the vaccine

Adjuvants

may also stimulate local inflammation

High and multiple vaccine doses may produce allergic reactions

Slide12

Toxoid

Vaccines

Chemically or thermally modified toxins used to stimulate active immunity

Useful for some bacterial diseases

Stimulate antibody-mediated immunity

Require multiple doses because they possess few antigenic determinants

Slide13

Vaccine Safety

Problems associated with immunization

Mild toxicity is the most common problem

May cause pain at the injection site can cause general malaise or fever high enough to induce seizures

Anaphylactic shock Is an allergic reaction that may develop to a component of the vaccine

Slide14

Residual virulence

Attenuated viruses occasionally cause disease in healthy children or adults

Allegations that certain vaccines against childhood diseases cause or trigger autism, diabetes, and asthma

Research has not substantiated these allegations

Slide15

Administration of preformed antibodies

Used when protection against a recent infection or an ongoing disease

the serum from human or animal donors that have been infected or immunized

Serum used for passive immunizations is called antiserum

Slide16

Passive vs. Active Immunization

Slide17