First line of defence (innate immunity): This is like a moat and castle walls, preventing invasion by foreigners. There are physical and chemical barriers to infection.
Second line of defence (innate immunity): If the foreign materials breach the first line of defence, an infection forms. This is the inflammation (heated battle) where invaders are being killed indiscriminately.
Third line of defence (active immunmity) : The last line of defence is the active, specific response by trained killer cells (ninjas!) that recognise their targets and actively seek them out and destroy them. They may be proteins or pathogens that have taken over the reproductive capacity of the cell (prions and viruses, for example), so the infected cell must be destroyed.
At the Gene Technology Access Centre for the “Body at War – Day of Immunology” seminar and workshops, you learned about pathogens, the human body’s response to antigens and how vaccines have been developed to reduce the spread of disease. You conducted ELISA tests to identify infected individuals and observed diseased tissues through microscopy. A valuable activity was the Immunology Game, which demonstrated the response to antigens at a cellular level and gave you the experience of controlling the movement of white blood cells (dendrites, plasma cells, macrophages and B and T cells) around the body.
GTAC also have several online courses that I would like you to complete this week.
How do cells communicate? In this area of study students focus on how cells receive specific signals that elicit a particular response. Students apply the stimulus-response model to the cell in terms of the types of signals, the position of receptors, and the transduction of the information across the cell to an effector that then initiates a response. Students examine unique molecules called antigens and how they elicit an immune response, the nature of immunity and the role of vaccinations in providing immunity. They explain how malfunctions in signalling pathways cause various disorders in the human population and how new technologies assist in managing such disorders.
Outcome 2 On completion of this unit the student should be able to apply a stimulus-response model to explain how cells communicate with each other, outline immune responses to invading pathogens, distinguish between the different ways that immunity may be acquired, and explain how malfunctions of the immune system cause disease.
In Area of Study 2: How do cells communicate? we study cellular signals (signalling molecules, signal transduction and apoptosis); responding to antigens (including antigens, innate and adaptive immunity and the lymphatic system) and the immune system (including diseases of the immune system and cancer immunotherapy). The following links are some resources for study in these topics.
Chapter 6: Cellular Signals
Chapter 7: Responding to antigens
Chapter 8: Immunity, immune malfunctions and immunotherapy
ELISA technique with materials supplied by Zoetis Australia.
This week we had another opportunity to connect with the Gene Technology Access Centre via Polycom. The topic of this session was the Hendra virus and a method to detect antibodies with a colour change (called ELISA – Enzyme-Linked Immuno-Sorbent Assay). We are very grateful to Zoetis for supplying the materials for this practical work and Fran at GTAC for stepping us through the process.
In a suburb of Brisbane in 1994, a horse-trainer and fourteen horses died of a mysterious illness within days of falling ill. CSIRO’s Australian Animal Health Laboratory, in Geelong, swung into action and worked intensively on blood and tissue samples for two weeks before identifying the virus responsible as Equine morbillivirus. However, further genetic analysis showed that the most appropriate classification of the virus was to place it in a new genus within the family Paramyxoviridae. It was later renamed Hendra virus, after the name of the Brisbane suburb in which the original outbreak occurred.
Zoetis Australia is a global animal health company who research and create animal medicines and vaccines, complemented by diagnostics products and genetics tests. As well as a Hendra virus vaccine, they have developed a technique for determining if an animal has virus antibodies present, which indicates that the individual has been exposed to the disease or has been vaccinated previously. We will use this technique to determine if three horses have had prior exposure to the disease or if they need to be vaccinated or receive booster shots.
If you suffer from allergies, you may be familiar with the image above. This person is having a ‘skin prick’ or ‘scratch’ test, in which a tiny drop of the possible allergen is pricked into the skin and the reaction measured. Allergens can be a wide variety of substances, from pollens and dust mite faeces to eggs, milk and nuts. Up to 40 different substances can be tested at once.
This is the link to our Google Presentation on the Immune System. I have allocated one slide with a topic for each pair of students. You can add another slide if you need to, but just a few brief dot points under the heading will be sufficient.
More sites for revision of Unit 3: Area of Study 2:
Sir Gustav Nossal at the Gene Technology Access Centre
On Tuesday 29th April, eight VCE Biology students attended the “Body at War” program for World Immunology Day at the Gene Technology Access Centre. The students joined with about eighty other students from government and independent schools to learn about the history, discovery and use of vaccinations against diseases such as smallpox and polio.
Students were welcomed by Prof. Phil Hodgkin, who spoke about the long history of immunology, including the famous scientists who have discovered how diseases can be prevented using vaccination. They then had the great privilege of hearing Sir Gustav Nossal, scientist and former Australian of the Year, speak about the progress of eradicating infectious diseases from across the world over the past two decades. They then rotated through three different workshops; learning about the bodies immune response through a computer game, identifying diseased mouse tissue using staining and microscopy and then simulating a Streptococcus pneumoniae diagnosis.
Students have been very fortunate to be invited to this special program, as only up to 10 students from selected schools were able to attend this free event. They also had the opportunity to work with working scientists in small groups and hear from three young scientists about their journey into research and career prospects for scientists.
Prior to attending the session, it was useful to know about pathogens, or disease causing agents. These range in size from the smallest sub-microscopic particles (prions) to multicellular organisms.
- Prions (BSE or mad-cow disease)
- Viruses (influenza, herpes, chicken-pox)
- Bacteria (tuberculosis, tetanus, Staphylococcus, Salmonella)
- Protozoans (malaria, amoebas)
- Fungus (athlete’s foot, Candida)
- Worms (tapeworm, nematodes)
- Ticks and mites
You can find out more about pathogens and the immune system here:
It will also be useful to watch the “Life on Us” program at 8.30pm Sunday night on SBS One. This two-part series has powerful imagery showing various microscopic pathogens that inhabit the human body – you can watch a short promotional video here.