Disease

What are antibiotics?

• chemicals that kill bacteria or inhibit their growth

• they interfere with specific metabolic pathways

• can be produced naturally by bacteria and fungi

• many are now produced synthetically

What are antibiotics effective against?

• only bacteria

• they do not effect eukaryotic cells because they have different structures and metabolic pathways

• they are ineffective against viruses

Who discovered antibiotics and when?

Alexander Fleming in 1928

How do antibiotic resistant bacteria occur due to the over-use of antibiotics?

• antibiotic is selective pressure

• variation in bacterial population due to mutation

• some bacteria has allele for resistance

• when exposed to antibiotics most resistant individuals survive and reproduce

• least resistant individuals in population die

• over many generations there is an increase in resistant population

• antibiotics become ineffective

• new antibiotic needed

What are superbugs?

• bacteria that have resistance to multiple antibiotics

• infections they cause are very difficult to treat

• spread more easily throughout population

What is an example of a superbug?

MRSA has acquired genes for resistance to all penicillins

What can we do to minimise build up of antibiotic resistance?

1. Use antibiotics wisely

2. Prevent infections

3. Reduce use in animals

4. Monitor and improve

5. Spread awareness (education)

How does using antibiotics wisely reduce antibiotic resistance?

• use only when prescribed

• never for viral infections

• complete full course

How can infection be prevented in order to reduce antibiotic resistance?

• wash hands regularly

• keep vaccinations up to date

• safe food handling

• infection control in hospitals

• hospital screening before admission

How can the use of antibiotics in animals be reduced in order to reduce antibiotic resistance?

• avoid use for growth promotion

• only use under veterinary guidance

• improve hygiene and vaccination

How can antibiotics be monitored and improved to reduce antibiotic resistance?

• track resistant pathogens

• support research

• rapid tests to guide treatment

How can we spread awareness about antibiotics to reduce antibiotic resistance?

• educate on misuse

• encourage responsible prescribing

Where does most of our modern medicine come from?

Traditional remedies from plants

What are two examples of modern medicines that come from traditional remedies made from plants?

1. morphine

2. aspirin

What was morphine been developed from and for?

• comes from the sap of unripe poppy seed heads

• 12th century opium was used as an anaesthetic

• 19th century morphine and opium were used

• drugs reduce nervous action in the nervous system

• if no impulses travel no pain can be felt

What was aspirin developed from and for?

• willow bark extract has been used to reduce pain and fever

• caused some issues with stomach bleeding

• 1897 found a way to reduce this

• led to development of aspirin and ibruprofen

How is research for new medicine carried out from traditional medicines?

1. aim to isolate active ingredient

2. tropical plants are the current focus

3. chemical fingerprinting digital technology has been developed

What is the advantage of researching plants already known to work in traditional folk medicine?

• quicker / easier to find

• cheaper than starting from scratch

• known side affects

• known dosage

• known interaction with other drugs

How are drugs designed based on research into mechanisms causing disease?

1. identifying significant receptors on cell membranes

2. blocking the receptors to prevent pathogen entering cell

• isolating and sequencing receptor molecules

• using molecular modelling to find the shape of the receptor

3. finding / creating a molecule that mimics the shape of the receptor molecule

• binds to virus

• virus can’t enter the cell

What is personalised medicine?

• medicine that has been artificially modified to account for individual differences

What are the positives of personalised medicine?

• potential for future medicines

• ability to sequence organisms genomes means it is possible to identify potential medicinal compounds from just DNA sequences

• potentially enables the manufacture of specific drugs for their conditions

What is pharmacogenomics?

• the relationship between an individual’s genetic make-up and their response to a drug

• it is an important part of personalised medicine

What are some examples of personalised medicine use?

• cancer treatments

• trastuzumab - used in breast cancer patients whose tumors overexpress the HER2 protein

What is synthetic biology?

• the use of genetic engineering techniques to develop populations of bacteria

• used as biological factories to produce much needed drugs

• the synthetic production of biological molecules

What is natural active immunity?

• immune system is activated and forms antibodies

• T and B memory cells produced

• on second meeting of pathogen the immune system recognizes the antigens

• immediately destroys the pathogen before symptoms develop

What is natural passive immunity?

• immune system of baby cannot make antibodies

• antibodies from the mother cross the placenta while fetus is in the uterus

• so the baby has some immunity at birth

• colostrum is high in antibodies

• they last until the immune system begins to make its own

• likely to be relevant to environmental pathogens where mother acquired them

What is artificial active immunity?

• stimulated to make antibodies by a safe form of the pathogens antigens (a vaccine)

1. pathogen is made safe

2. small amount of safe antigen

3. primary immune response triggered

4. secondary response triggered when live pathogen enters system

• may last years - lifetime

What is artificial passive immunity?

• for potentially fatal diseases

• they are formed in one individual, extracted, and then injected into bloodstream of another

• temporary immunity may be lifesaving

• prevents development of disease but don’t provide long term immunity

What occurs in active immunity?

• lymphocytes are activated by antigens

• specific immune response is produced

What occurs in passive immunity?

• antibodies are introduced into the body and these provide immunity

• no activation of lymphocytes occurs

What happens during vaccination?

• antigens are introduced into the body

• a specific immune response is produced

• results in artificial active immunity

What are the different types of vaccines?

• live

• dead

• subunit

• genetically engineered

What is a live vaccine?

• living whole organism introduced

• attenuated microorganisms introduced (harmless/weaker)

What is a dead vaccine?

Dead whole organisms introduced

What is a subunit vaccine?

• isolated surface antigens introduced

• contain some parts of microorganisms

• e.g. inactivated toxins

What is a genetically engineered vaccine?

genetically engineered antigens introduced

What is an epidemic?

When a disease suddenly spreads rapidly to affect many people

What is a pandemic?

When a disease suddenly spreads over a very large area e.g. continents, whole world

What is herd immunity?

The majority of a population is immune to a particular disease

What is ring vaccination?

• used during epidemics

• controls the spread of disease

• all individuals in contact with initial case are vaccinated

What are some problems with vaccination?

• poor response

• antigenic variation

• eukaryotic pathogens

• antigenic concealment

• safety concerns

What is a poor response to vaccination?

Some people do not respond well to vaccination e.g. malnutrition / immunodefficiency

Why is antigenic variation an issue with vaccination?

Pathogens mutate regularly to give different antigens

What is antigenetic shift?

Major change in antigens of a pathogen

What is antigenetic drift?

Minor change in antigens of a pathogen

Why are eukaryotic pathogens a problem for vaccination?

• they are more complex

• they have more antigens and a complex lifecycle

• this makes vaccine development of vaccines difficult

Why is antigenic concealment a problem for vaccination?

• some pathogens hide inside host cells

• reduce the time available for an immune response

What are safety concerns of vaccinations?

Vaccines can cause side effects individuals may be hypersensitive or allergic (to either antigen or ingredients)

What is a non-specific immune responses?

• Are present from birth and do not distinguish between pathogens

• They do not give any lasting immunity

What is a specific immune response?

• Are acquired during organisms lifetime and can distinguish between pathogens

• They result in immunological memory that gives lasting protection to that specific pathogen

What is an eosinophil?

Phagocytes that migrate to lymph nodes during infection causing swelling

What are B lymphocytes?

• originate and mature in the bone marrow

• produce antibodies

• responsible for humoral immunity

What are T lymphocytes?

• originate in the bone marrow

• mature in the thymus gland

• responsible for cell-mediated immunity

How are B lymphocytes activated?

By the pathogen antigens immediately

How are T lymphocytes activated?

By modified body cell

What receptors do T cell have?

T cell receptors

What receptors do B cells have?

Antibody receptors

What are some examples of cells which a T lymphocyte would respond to?

• virus infected cell

• mutated cells (early cancer cells)

• transplanted cells

• antigen presentation by macrophages

How is a T cell lymphocyte activated by antigen presentation?

1. phagocyte eats a bacteria

2. antigen of bacteria goes to the surface of phagocyte

3. phagocyte presents the antigen to the helper T cell

4. helper T cell is activated

How does antigen presentation occur?

• macrophage engulfs a pathogen

• process the antigens by combining them with glycoproteins in the cytoplasm

• called the major histocompatibility complex

• the MHC moves pathogens antigens to the cel surface membrane

• macrophage is now an antigen presenting cell

What are the steps in T cell activation?

1. clonal selection

2. clonal expansion

3. differentiation

What is clonal selection in T cell activation?

• specific T helper cell binds to presented antigen

• (complimentary binding)

• the APC secretes interleukins

• they activate selected T cells

What is clonal expansion of T cells?

• selected T cells, stimulated by interleukins divide rapidly

• form identical clones of T helper cells

• all the cloned cells carry the same complementary receptor to a particular antigen

What is an interleukin?

A type of cytokines promote the differentiation of cloned T cells

What are the types of T cells?

• Helper T cells

• Killer T cells

• Regulatory T cells

• Memory T cells

What is a helper T cell?

• release interleukins which stimulate B cells to divide

• B cells differentiate into plasma

• also activate killer T cells

What is a killer T cell?

• seek out and destroy infected cells or non-self cells

What is a regulatory T cell?

• inhibit other cells in the immune systems once pathogen has been eliminated

• act as a control to prevent autoimmune responses

What is a memory T cell?

• remain in the body for a long time

• reactivate quickly during secondary response

• gives immunological memory

How do killer T cells destroy pathogens?

• attach to an antigen presenting cell

• secrete perforins to lyse the cell membrane

• release toxins (e.g. H₂O₂) to destroy the cell

What are two examples of autoimmune diseases?

1. HIV / AIDS

2. rhumatoid arthritis

What does AIDS do?

Specifically target helper T cells

What type of antigens do B lymphocytes respond to?

On the outside of organisms cells

• surface of bacteria

• surface of fungi

• soluble antigens e.g. toxins from bacteria

What is clonal selection of B lymphocytes?

• antibody receptors on the B lymphocytes bind to specific antigen

• interleukins from helper T cell are also required to activate the B cell

What is clonal expansion?

Cells divide rapidly by mitosis to form clones

What type of cells can B cells differentiate into?

1. plasma cells

2. B memory cells

What do plasma cells do?

• quickly synthesise and secrete antibodies

What do B memory cells do?

• remain in the body for a long time

• reactivate quickly during secondary response

• give immunological memory

What are the differences of antibody production in primary and secondary responses?

Primary

• takes longer

• often feel symptoms

Secondary

• rapid response

• higher concentration of antibody produced

• often don’t feel symptoms

What are the three regions of an antibody?

1. constant region

2. variable region

3. hinge regions

What is an antibody made up of?

• 2 long polypeptide chains

• 2 short polypeptide chains

• held together by disulphide bridges

What is the constant region of an antibody?

• same in every antibody

• enables antibody to bind to phagocytes and induce phagocytosis

What is the variable region in an antibody?

• different in every type of antibody

• complimentary to the antigen they bind to

What is the hinge region of an antibody?

allow flexibility to bind to more than one antigen

What is agglutination?

large antibodies can cause pathogens to stick together, meaning they:

• form a group too large to enter a host cell

• they are less mobile

• easier for phagocytes to enguls

What is opsonisation?

Antibodies bind to pathogens and tag them for recognition by phagocytes

How do antibodies work?

• act as anti-toxins

• immobilisation

• neutralisation

How do antibodies act as anti-toxins?

• bind to toxins produced by pathogens

• toxin is made harmless

How do antibodies cause immobilisation?

• binds to bacterias flagela

• stops bacterium from moving

How do antibodies cause neutralisation?

• cover the pathogen binding sites

• preventing from binding to a host cell and entering

What are primary defences?

The initial barriers that prevent pathogens entering the body

What happens when pathogens enter the body?

The secondary defences are triggered

What are the two types of secondary response?

1. specific

2. non specific

What are the primary defences of the body?

• Skin

• Eyes

• Mucous membranes

• Stomach

• Expulsive reflexes

• Blood clotting

How does the skin act as a primary defence against pathogens?

• Physical barrier - blocks pathogens from entering the body

• Chemical barrier - produces antimicrobial chemical that destroy / slow the growth of organisms

How do the eyes act as a primary defence against pathogens?

• Tears contain antibodies

• Also contain the enzyme lysozyme

How do mucous membranes act as a primary defence against pathogens?

• Protect body openings from environment

• Secrete mucus that traps pathogens

• Secretes antimicrobial chemicals

How does the stomach act as a primary defence against pathogens?

• Contains stomach acid (HCl)

• Too acidic for pathogens to survive

How do expulsive reflexes act as a primary defence against pathogens?

• e.g. coughing and sneezing

• happen automatically

• sneeze = mucus membrane in the nostrils is irritated

• cough = irritation in the respiratory tract

How does blood clotting act as a primary defence against pathogens?

• prevents entry of pathogens

• prevents further blood loss