1. Learning Objective Describe viruses and viral diseases To be able to:
Key Words:
Virus, HIV, antiviral drug

2. Exam question Tuesday, 21 May 2019 Viral Diseases
Date and title in books. You need a pen, pencil & a ruler.
Starter Activity – 5 minutes
Exam question

3. (F)
Target 1-9
State that viral diseases may reproduce rapidly and produce toxins
(F/H)
Target 4-9
Describe how viruses affect cells
(H)
Target 5-9
Use information to explain how a range of viruses can affect the body or a plant
Extension: Application of Knowledge
Target 8/9
Use data to analyse the effects of a virus
Learning Outcomes

4. Viruses Facts: Very small Cannot survive outside of another cell
Live and reproduce into cells
Cause cell damage

5. Measles
Symptoms: fever and red skin rash. Can be fatal if complications arise.
Spread: coughing and sneezing, inhalation of droplets
Treatment: vaccination given to all children as part of the MMR vaccination

6. HIV
Symptoms: Flu-like virus. Attacks the body’s immune system. Develops into AIDS, which means the body cannot protect itself from other infections or cancers. Death.
Spread: Sexual contact, body fluids such as blood.
Treatment: Currently, incurable. Antiviral drugs used to slow down the immune system attack.

7. Diagram of an HIV Virus Size: 1/10,000 of a millimetre (0.1m)
RNA (similar to DNA, contains genetic information)
Protein coat (or capsid)
These are proteins which help virus enter host cells

8. AIDS – Acquired Immune Deficiency Syndrome is caused by
AIDS – Acquired Immune Deficiency Syndrome is caused by HIV – Human Immunodeficiency Virus.
HIV will gradually destroy the person’s immune system.
Epidemic started in 1980’s
Approximately million die each year
31-36 million currently living with HIV/AIDS (as of 2011 survey)

9. How can the virus infect us?
The virus can enter the body via infected body fluids:
during vaginal and rectal sex
drug-taking using infected needles
blood infection of wounds/needlestick
blood transfusion and blood products
The virus may also pass from mother to child across the placenta during pregnancy, and via breast milk
HIV cannot be contracted by touching or hugging an AIDS sufferer

10. How can HIV be prevented?
AIDS is a true pandemic
However, its spread could be controlled:
Safe sex (using condoms and femidoms)
Avoid promiscuity (have one partner)
Don’t share needles
Screen all blood, donors, and blood products
Extreme care when dealing with known AIDS sufferers (e.g. needlestick injuries)
HIV testing of sexual contacts
The main aim of Health Agencies across the world should be Education

11. Tobacco Mosaic Virus (TMV)
Plant pathogen
Attacks many species of plant, such as tomatoes.
Leafs a mosaic, discoloured pattern on leaves, due to lack of photosynthesis.

12. Other viruses

13. This is an electron microscope photograph of an Adenovirus particle
This is an electron microscope photograph of an Adenovirus particle. Adenoviruses are a common cause of sore throats and serious lung infections in humans.
The Adenovirus virion is made up from 252 identical protein building blocks which make up a protein coat or capsid. These are wrapped around a molecule of DNA. Fibre projections stick out from the Adenovirus particle. These projections help the virus attach to the cells lining your throat.

14. Influenza virus - Picture taken using an electron microscope
Influenza viruses contain eight RNA molecules surrounded by viral proteins. The influenza virus outer surface has spikes which are important for entry into host cells.

15. Polio virus - structure shown here in a 3D reconstruction based on electron microscope pictures and X-ray crystallography data.
The polio virus is a small RNA-containing virus with a simple spherical structure.

16. Bacteriophage - a virus which uses a bacteria cell as host
Left picture is an electron microscopy picture of Bacteriophage Lambda. Right picture is a schematic drawing of another bacteriophage.