Lecture 16: vaccination

What is variolation

Deliberate infection of a controlled amount of infectious agent to induce infection & immunity

When was variolation introduced into the UK & where from

In 1721 from the Middle East, China & Africa

What is vaccination

Using a minor form of infection to protect against a major form

The scientific method used to produce vaccination

• Observation

• Hypothesis

• Experiment

• Results

• Publication

Attenuation

Methods to prepare weakened versions of infectious agents as vaccines.

Variola

Infection

Vaccina

Vaccination

How is the efficacy of vaccines tested

Using animal models

What went wrong for Louis Pasteur

He grew cholera in a lab & forgot to sub-culture it when he went on holiday for 2 weeks which caused it to over grow

Sabin polio vaccine: virus attenuation

1. Pathogenic virus isolated & cultured on host cells (human)

2. Virus incubated on cell from another host (monkey)

3. Virus spontaneously mutates & grows on 2nd host's cells (monkey)

4. Virus can be used as a vaccine as it cannot grow on 1st host's cells (human)

2 types of vaccines

Killed, subunit, live attenuated, subunit (conjugate), recombinant subunit

Killed vaccines

• Chemicals used to heat or kill organism & render it completely uninfective

• Antigens from the killed organism can still induce immunity

Subunit vaccines

• Isolate antigens from cultivated viruses or bacteria

• Antibodies to antigens can protect against infection.

Toxins

Disease causing parts of pathogens

Toxoids

Inactivated forms of toxins that could protect against disease

What are naive T & B cells

Lymphocytes that have never seen an antigen

Clonal expansion

Rapid multiplication of T and B cells to increase the number of antibodies

Secondary immune response

Generate much more antibodies which act much faster