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12 Cards in this Set

  • Front
  • Back

Define a symptom

Any evidence of a diseases that cannot be detected by an observer, only the sufferer. e.g. pain

What is a clinical sign?

An objective physical finding. e.g. elevated blood pressure

What is the minimum infectious dose of a virus?

The amount of virus required to initiate a disease (which will vary from person to person)

The strength of a particular virus can be measured using certain parameters. Virulence is one such parameter. What is it?

Virulence is the capacity to cause disease in a population (quantitative)

The strength of a particular virus can be measured using certain parameters. Pathogenicity is one such parameter

Pathogenicity is QUALITATIVE ability to cause disease in a host

What is attenuation, in the context of a virus?

When you can monitor the reduction of virulence in a particular viral strain

What is the key difference between pathogenicity and virulence?

Pathogenicity is more of a qualitative measure, whereas virulence is more of a quantitative measure of the disease producing capabilities of a virus.

What area of adaptive immune system is used to regulate viral infections?

T cell and B cell responses

What branch of the innate immune system is used to regulate viral infections?

The interferon response

What is the main action of interferons to regulate viral infections?

Interferons act as signalling molecules that heighten the viral defences of nearby molecules

Describe how the interferon response regulates viral infections.


1. Cells infected by virus send out interferons so that neighbouring cells initiate antiviral defences

2. The interferons stimulate RNAseL, which destroys all RNA within the cell

Antiviral Action

1. The interferon molecule will activate a kinase

2. The kinase phosphorylates EIF2 with GDP attached, making it bind irreversibly

3. Protein synthesis and translation are prevented within the cell

4. Cells will then undergo apoptosis

There are 3 major types of interferons. Describe them

1. Alpha &Beta are type 1 interferons, made in response to a cell-virus infection. Can up regulate the action of MHC class I molecules

2. Gamma is the type 2 interferon, released by T cells in response to a viral infection. It can up regulate MHC class i and ii activity