Microbes: viruses

Introduction
Public summary: 

Viruses are tiny particles that infect animals and plants - causing infections like chicken pox. Come and have a look at our cuddly viruses and hear more about what they do!

Cuddly viruses and a few models too
Useful information
Kit List: 

A small grey box labelled "microbes (viruses)".

• 11 x cuddly viruses
• 1 x plastic model HIV virus (in box) and string ('DNA')
• laminated fact sheets
• microbiology text book

Packing Away: 

Please make sure that we have all the cuddly microbes, and that they go back in the right box.

Frequency of use: 
5
Explanation
Explanation: 

Overview

Cuddly viruses and virus models to demonstrate. This experiment can be combined with the bacteria and parasites boxes too – all were new for the 2011 Summer Roadshow so are very open to suggestions for improvement!

Tips for demonstrating:
- Lay out the cuddly viruses on the table and let children pick them up and ask you what they are
- Ask questions to see what the children know about viruses and start from there!
- If it's busy it might be easier to keep most of the viruses in the box and bring them out one at a time to help control questions
- You can use the plastic virus model to give a more realistic representation to your group (better for older children)
- There is some more information about each cuddly virus on the attached labels in the box

Viruses box

Viruses can be as simple as DNA or RNA in a protein coat. Viruses use the host cell’s machinery to make lots of new virus particles (virions). Often viruses are released from cells by making them burst (lysis). Others gradually bud off from the cell, taking some membrane with them and the cell survives (eg. HIV), giving a continuous release of virus particles. Viruses can’t survive for very long outside of cells so new virions quickly find a new cell to infect. Viruses are also very ‘clever’ as they have lots of strategies to subvert the host cell function eg. by stimulating the host cell to divide so there is enough replicative machinery in the host cell to make lots of virus.

HIV (Human Immunodeficiency Virus): Retrovirus (RNA genome copies itself into DNA, using viral reverse transcriptase. The DNA integrates into the host chromosome and new viral genomes are produced by host transcription/translation machinery)
Can be spread via some bodily fluids and blood. Lives in white blood cells (CD4+ helper T cells) and eventually kills them, which means the immune system cannot function properly. People where HIV has killed too many white blood cells have AIDS (acquired immune deficiency syndrome), and this means that they can become very ill or even die from diseases that would not harm a healthy person (opportunistic infections – a big killer is tuberculosis caused by Mycobacterium tuberculosis – cuddly bug in the bacteria box).

Common Cold (Rhinovirus): positive sense RNA
Spreads easily from infected people when they sneeze or contaminate surfaces. The virus is very happy at the temperature and conditions in the human nose which is where they initially infect. There are lots of different types of rhinovirus whose protein coats all look different to the immune system, which is why we don’t get become immune to the common cold.

Measles (Morbillivirus): negative sense RNA virus
Usually spread by breathing in virus from droplets in the atmosphere. Causes a fever, rash and red eyes. Most people will have been vaccinated against this with the MMR jab, which mostly eradicated measles from the UK. However since the scare about the MMR jab (spuriously linked to autism), the disease has been cropping up in affluent areas of London! (Vaccine scares can destroy herd immunity, the protection the population has when enough people are vaccinated and the virus cannot find enough hosts to spread to.)

Kissing Disease (Epstein-Barr Virus): DNA virus
Most of you will have this virus right now. It is usually spread via saliva, causing a mild fever in the majority of the population in early childhood. (Lots of people have asked me why this is and the answer is we don’t really know – scientists think it might be something to do with how the immune response develops over childhood.) However some people who don’t get the virus in early life might get it when they come into contact with other people’s saliva in their teenage years - they then get Glandular Fever. An interesting thing about the virus is that you never really get rid of it; some of its DNA forms little circles in the nucleus of the white blood cells it infects, and it can remain dormant (latent infection) for a long time (occasionally getting out into saliva but not making you ill). The virus that causes chicken pox can do this in nerve cells.

Influenza: Negative sense RNA virus
Infects almost all mammals (eg. swine flu, bird flu), aquatic birds are primary host. Common problem in humans - see most in winter when low air humidity allows the visus to spread more effectively. Spread by breathing in virus particles (Respiratory tract). Causes symptoms including fever, headache, cough, muscle aches and less commonly vomiting and diarrhoea. It can be vaccinated against, however it is able to change its structure (by mutating its genome which is a random process) so it can evade the immune system. This means flu vaccines keep having to be updated to protect people against the new variations of the virus. This, and the fact that influenza virus also infects birds, is the reason why it would not be possible to eradicate influenza. Could compare this to viruses like smallpox and polio which have or have nearly been eradicated because they have more stable genomes and no animal reservoir.

Rabies: Negative sense RNA virus
Enters via skin and exits via saliva - spread through being bitten by an infected animal (usually dog). Results in death by killing brain cells in the cerebellum. The virus travels to the brain from the bite site up the nerves and it progresses slowly, so it is possible to stop the progression of the disease by vaccinating after being bitten.

Ebola: Negative sense RNA virus
Spreads by direct contact. This virus has a high fatality rate of up to 90% (but closer to 40% in the most recent outbreak). It causes symptoms including fever, muscle aches, skin rash, vomiting + diarrhoea, weakness, bleeding from nose, mouth etc. The virus can infect many cell types and it spreads within the body through the circulatory system. It causes such severe disease because it causes clotting within the blood vessels, bleeding inside the body (haemorrhage) leading to a drop in blood pressure and multi-organ failure. It is also so severe because it originated in a different animal to humans - the fruit bat - and transmitted to humans relatively recently. This is in contrast to viruses such as the common cold which have been in human populations for a long period of our evolution meaning we have adapted to survive it.

Winter Vomiting Disease (Norovirus): Positive sense RNA virus
Very common in the UK and very contagious. Causes vomiting and diarrhoea. Spread can be prevented by washing hands regularly.

Polio: Positive sense RNA virus
See "Polio, vaccination and disease eradication" experiment

Chicken Pox: Double stranded DNA virus
Otherwise known as Varicella-Zoster virus, a member of the herpesvirus family. Highly contagious; Spread through direct contact, coughing and sneezing, and causes red spots on the skin all over the body. Causes mild symptoms if caught when young, but causes Shingles in adults which is more serious. After initial infection, the virus goes dormant (latent) in the nervous system, and later in life it might reactivate to cause shingles.

T4 (T4-Bacteriophage):
Bacteriophage are viruses but they do not infect humans – they infect bacteria. One day this might be useful to us for treating bacterial infections (‘phage therapy’) where you can infect specific bacterial cells with genes that kill them/stop them reproducing.

HPV, here's, cancer (not virus)

Risk Assessment
Date risk assesment last checked: 
Mon, 08/01/2018
Risk assesment checked by: 
gcs33
Date risk assesment double checked: 
Fri, 02/02/2018
Risk assesment double-checked by: 
Miffles
Risk Assessment: 

DESCRIPTION: Microbe toys and accessories

RISKS
1.Trip hazard if dropped on the floor

ACTION TO BE TAKEN TO MINIMISE RISKS
1.Keep all props in contained area

ACTION TO BE TAKEN IN THE EVENT OF AN ACCIDENT
1.Call first aider in case of injury

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