Biology - Chapter 8 Immunity

Natural active immunity

No medical intervention and the use of one’s own immune system to create antibodies and memory cells e.g. humoral response

Natural passive immunity

no medical intervention and antibodies are created by a natural external source. e.g. breastfeeding

Artificial active immunity

A person develops their own antibodies and memory cells after getting vaccinated

Artificial passive immunity

Antibodies are created by an artificial external source. e.g antivenom

What pathogen is in vaccines?

attenuated (weakened)

inactivated (dead)

toxoids (toxins with altered DNA)

Primary immune response (1st shot)

• delay in the adaptive immune response since time is required to find T and B cells complementary to the vaccine’s antigen

• some antibodies form and memory cells are stored

Secondary immune response (2nd shot)

• memory cells created after the first vaccination recognise the antigen

• large amount of antibodies created

• faster response and longer lasting immunity

Booster vaccines

• needed since over time b and t cells die

• required to stimulate remaining memory cells to generate more antibodies and more memory cells

• given after a vaccination program

Herd Immunity

When the majority of a community are immunised to a disease to prevent the spread of a disease to those who have not been vaccinated. Plus, the more people vaccinated, the less chance of the disease spreading.

Non-infectious diseases

Illness not caused by pathogens but abnormal genes, lifestyle, cancer. e.g diabetes

Infectious diseases

Diseases caused by pathogens that harm the host. e.g Ebola virus

Contagious

how easily the disease is transmitted

Virulent

How severe the pathogen is

Emerging disease

Diseases that have not occurred in humans before, have occurred previously but only affected populations in isolated places, or have occurred throughout history but have only been recognised as caused by pathogens.

Re-emerging disease

Diseases that were once a major health problem and then declined dramatically in incidence, but then again becoming a health problem for many people.

Factors that influence the emergence and re-emergence of pathogens

• evolution of organism

• travel

• zoonosis

• increased population

• poor vaccination rates

• lack of sanitation

• human behaviour

• misuse of antibiotics

Epidemic

widespread of infectious disease among a specific population at a particular time.

Pandemic

widespread of an infectious disease to different countries and continents.

Endemic

constant baseline level in a population

why were indigenous Australians struggling with the pathogens brought by settlers?

• lack of immunity

• lack of knowledge

• disruption caused by colonisation

ELISA test

1. antibodies specific to a certain pathogen are attached to a plate

2. Serum is added to the plate, If the serum contains the specific antigens, they will attach to the antibodies creating antigen-antibody complexes.

3. Enzyme are added. If antigen-antibody complexes form, then the enzyme will attach

4. Substrate is added to allow the enzyme to change colour if a antigen-antibody complex is formed.

How can scientists determine the pathogen - physical

using a microscope to identify the pathogen by seeing the structure of it.

How can scientists determine the pathogen - phenotypic

use of agar plates to allow certain pathogens to grow. The use of certain chemicals on agar allow the growth of certain pathogens.

How can scientists determine the pathogen - immunological

diagnosis based on the presence of antibodies of antigens in a person’s serum and the use of the ELISA test.

How can scientists determine the pathogen - molecular

genomic sequencing to identify the pathogen. Use of hybridisation-based detection which uses labelled segments of genetic material which are complementary to a pathogen’s genetic material. If a signal is generated, the pathogen is present.

Types of disease transmission

• airborne - sneezing or coughing creates aerosol droplets of infectious particles

• droplet - respiratory droplets containing pathogens can fall on surfaces and transfer if a person touches their eyes, mouth or nose

• direct physical contact - via touch, exchange of bodily fluids, sexual contact, mother to baby

• indirect physical contact - spread through vectors or consumption of contaminated food, water or needles

• faecal-oral - pathogens from faeces can be consumed via contamination of food or water

Disease prevention

• keeping pathogen vectors away

• use of personal protective equipment (ppe)

• use of disinfectants (for surfaces) and antiseptics (for bodily tissues)

• education

• vaccination

Controlling disease

• quarantine

• isolation

Controlling disease transmission

• antibiotics - break cell wall of bacteria and stops replication. broad or narrow spectrum

• antiviral drugs - prevents virus from entering or reproducing in host cells and stops translation of the viral genome

• fungicides - treat fungal disease

Production of monoclonal antibodies

1. identify and isolate an antigen found on the desired cell.

2. Produce a vaccine and vaccinate mice to produce antibodies against the antigen

3. Scientists extract the B lymphocytes from the spleen of mice

4. Extracted B lymphocytes are fused with myeloma cells to form hybridomas.

5. Hybridomas are selected and are cloned to produce large amounts of antibodies

6. Antibodies are collected and administered to the same cancer patient

How do monoclonal antibodies work?

• antibody-dependent cell-mediated cytotoxicity - monoclonal antibodies bind to cancer cells attracting other immune cells to destroy them

• Complement activation - monoclonal antibodies bind to cancer cells and interact with complement proteins to form a membrane attack complex

• Conjugate monoclonal antibodies - monoclonal antibodies with a chemotherapy drug attached and are delivered to cancer cells when antibodies bind to the antigen. Targeted and specific therapy compared to radiotherapy or chemotherapy that kills healthy cells