Vaccination

VACCINATION

When scientists first encountered Chickenpox and Smallpox, they got the idea for the world’s first vaccine. Smallpox is a deadly infection which in most cases was lethal. Whereas chickenpox was relatively much milder. The scientists then, believe it or not, actually advised the populations to get themselves infected with chickenpox. This was because the protein on either of those pathogens, which was used by the B cells to generate an immune response in the body (antibody production) was the same protein. By infecting oneself with Chickenpox, a person could lead to the immune response in their body ready for smallpox pathogen if and when they encountered it. This is the principle behind vaccination.

Viruses

Before moving ahead with other topics under Vaccination, let us discuss some more about Viruses.

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Characteristics of Viruses:

Borderline between living and non-living

Non-cellular organisms that are characterised by having an inert crystalline structure outside the living cell.

Have a protein and genetic material that is infectious.

That infect plants have single stranded RNA and viruses that infect animals have either single or double stranded RNA or double stranded DNA.

Bacterial viruses or bacteriophages (viruses that infect the bacteria) are usually double stranded DNA viruses.

The protein coat of the virus is called capsid made of small subunits called capsomeres, protects the nucleic acid.

These capsomeres are arranged in helical or polyhedral

geometric forms.

Viruses can cause many diseases in plants and animals.

Viroid: In 1971, T.O. Diener discovered a new infectious agent that was smaller than viruses and caused potato spindle tuber disease. It was found to be a free RNA; it lacked the protein coat that is found in viruses, hence the name viroid. The RNA of the viroid was of low molecular

Active and Passive Vaccination

In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body. The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection. The vaccines also generate memory – B and T -cells that recognise the pathogen quickly on subsequent exposure and overwhelm the invaders with a massive production of antibodies.

If a person is infected with some deadly microbes to which quick immune response is required as in tetanus. We need to directly inject the preformed antibodies, or antitoxin (a preparation containing antibodies to the toxin). Even in cases of snakebites, the injection which is given to the patients, contain preformed antibodies against the snake venom. This type of immunisation is called passive immunisation.