Describe the steps in the normal immunological response to common and important viral infections eg. Influenza, herpes viruses

- Interferons (mainly type 1).

- Natural killer cells.

Innate immunity to viruses includes which two key mediators

- Virally infected cells produce and release it.

What is the stimulus for production of interferons?

- Prevent replication of viruses.

- Act as signalling molecules, nearby cells are warned and up regulate MHC 1 receptors for the T-cell response.

What are some of the ways interferon 1's play a role in immunity against viruses?

- Interferon alpha and beta.

What are the two types of interferon 1's?

- B cells, epithelial cells, monocytes, macrophages.

What cells secrete interferon alpha?

- Fibroblasts mainly.

What cells secrete interferon beta?

- Interferon gamma and lambda.

What are the two types of interferon 2?

- Activated T cells (Th1) and NK cells.

What cells secrete interferon gamma?

- Interferon gamma.

Which interferon is the defining component of the type 4 hypersensitivity response?

- Mainly anti-influenza responses.

What response is interferon lambda involved in?

- Early cellular response to viruses.

- Anti-tumour activity.

- Amplification of inflammatory reactions following bacterial infection.

- Activate macrophages by releasing interferon gamma.

Role of natural killer cells in viral immunity

- Interferon alpha.

- IL-12.

What two molecules activate natural killer cells?

- Finds a cell with fewer than normal MHC 1 receptors on surface (virally infected cells often reduce MHC 1 expression).

- Releases toxic substances to kill cell.

Natural killer cells mechanism of action

- Have T cell receptors on their surface which recognise antigens displayed on MHC 1 receptors of the virally infected cell.

How do cytotoxic T cells recognise virally infected cells?

- Recognises virally infected cell.

- If TCR binds to MHC 1 receptor then the T cell releases cytotoxic factors to kill the infected cell.

- Therefore prevents survival of invading virus.

Cytotoxic T cell mechanism of action

- Yes.

Are cytotoxic cells and natural killer cells granulated?

- Protein that can make pores in cell membranes.

- Allows entry of other factors into target cell which facilitates its destruction.

- Stored in granules of cytotoxic T cells and NK cells.

Describe perforin

- Enter target cells through pores made by perforin.

- Initiates apoptosis.

- Stored in granules of cytotoxic T cells and NK cells.

Describe granzymes

- Protein that directly attacks outer membrane of target cell.

- Destroys it by lysis.

- Stored in granules of cytotoxic T cells and NK cells.

Describe granulysin