Option: Immunology and disease

Sporozoites

The infective stage of malaria, which is passed to humans after being develop in the mosquito’s gut and waiting in salivary glands. It is transmitted during feeding and travels to the liver.

Merozoites

Plasmodium cells developed in liver cells via asexual reproduction. Then released into the blood, infecting red blood cells, sexually reproduce and cause the cells to burst and fever symptoms. They then infect more cells.

Gametocytes

Taken into a mosquito if it takes blood from an infected person. These produce zygotes in the gut, which develop into sporozoites and move to the salivary glands.

Anopheles

Type of mosquito which carries malaria, which lives in sub-tropical regions. During wet seasons, it causes malaria to become an epidemic.

Quinine and artemisinin

Drugs used to treat malaria, one developed in the 17th century which has lost effectiveness and one with documented resistance. Ultimately, malaria is treated with a combination of drugs, as it is unlikely malaria is immune to all of them.

Plasmodium

Protoctista which causes malaria. Prevented by sleeping under treating mosquito nets, draining stagnant water, sterilisation, and biological methods such as fish. Can only be treated when in blood, which is becoming an issue due to resistance.

Pathogenic

An organism that causes disease.

Infectious

A disease that is transmittable, either by inhalation, consumption or physical contact.

Carrier

An infected person showing no symptoms but able to infect others.

Disease reservoir

A long term host of a pathogen, with little to no symptoms, but able to infect others.

Endemic

A disease occurring constantly, at a predictable rate, at a specific location.

Epidemic

Rapid spread of infectious disease to a large number of people in a small amount of time.

Pandemic

Widespread occurrence of an infectious disease over a country or the world.

Vaccine

A weakened or killed pathogen, or a toxic or antigen derived from it, which stimulates the immune system to cause a response without causing infection.

Antibiotic

A substance produced by a fungus which diminishes bacterial growth.

Antigen

A molecule which causes the body to produce an immune response.

Antibody

A blood protein produced in response to and counteracting a specific antigen.

Resistance

When pathogens become immune to the drugs used to kill and treat them.

Vector

A person, animal or microbe that carries and transmits an infectious pathogen into another person.

Toxin

A small molecule, such as a peptide, produced in cells or organisms that causes disease following contact or absorption. These often affect macromolecules.

Vibrio cholera

The gram negative, comma shaped bacteria which causes cholera. It is transmitted through contaminated food and water. Infected become reservoirs and carriers. Treated with electrolytes orally or intravenously. Has a temporary vaccine.

Chlorine channel proteins (CFTR)

The toxin produced by vibrio cholera affects these in the small intestine. This prevents water, sodium, chlorine, etc. absorption, causing severe watery diarrhea, dehydration, low blood pressure and death.

Mycobacterium tubercuolsis

A bacillus bacteria which causes TB. Spread by aerosol transmission via sneezes and coughs. Has a vaccine. Treated with antibiotics.

Tubercles

Nodules of dead and damaged cells in the lungs of those with TB. Also causes chest pain, bloody sputum, swollen neck lymph nodes, loss of appetite and fever.

bacillus of Calmette and Guerin (BCG)

Vaccine made from an attenuated strand of a related bacterium, M.bovis. Given to babies, and those with a negative skin test up to 16. Provides 75% protection for up to 15 years, and less effective in adults.

Variola major

A DNA containing virus which causes smallpox, which is completely extinct except for in labs. Spread through inhalation or saliva. Enters small blood vessels in the skin, mouth and throat and is then dispersed around the body, causing a rash and fluid filled blisters which scar. Can also cause blindness and limb deformities.

Vaccina virus

What virus the smallpox vaccine is made from. Led to the complete elimination of the virus, except for in the lab. Prior to this, isolation was used.

Influenza

Has three subtypes, A, B and C; A is the most common. It has 8 strands of RNA as a genetic material, and has a phospholipid membrane derived from the host cell’s surface membrane. Spread via aerosol transmission.

Haemagglutinin and Neuraminidase (H and N)

The two important proteins which act as antigens for influenza. There are many types, which can combine. The virus attacks mucous membranes, especially in the upper respiratory tract, causing a sore throat, cough and fever.

Animal reservoirs

Source of a new infection, produced when a virus mutates and becomes infectious to humans. For influenza, pigs and chickens are particularly high risk. During transmission, the disease is protected by a mucous, and it survives better in dry and low UV light conditions - winter.

Antigenic types

When different individuals of the same pathogenic species have differing surface proteins, and therefore antibodies. Can develop via antigenic drift of shift.

Drift

When antigenic types develop due to a lack of RNA proofreading enzymes, meaning a mutation occurs on average after every round of replication. This causes a gradual change in surface proteins.

Shift

When antigenic types develop due to combining antigenic types, such as influenza with H and N. This occurs when two different viruses infect a single cell, causing separate strands of RNA to recombine. This can cause epidemics.

Lytic

Cycle of bacteria where they immediately reproduce using the host’s metabolism, copying their own nucleic acids and synthesising a new protein coat. This occurs via a virion attaching, injecting it’s nucleic acid, this and capsid protein are then synthesised by the host cell metabolism to make mature virus particles and the cell lyses.

Lysogenic

Cycle where viruses integrate their nucleic acid into host cell genomes and remain there for many cell generations with no clinical effect. Later, they are triggered to enter the lytic cycle and produce symptoms.

Antimicrobials

Compounds that inhibit the growth of bacteria, including antiseptics used on living tissue (Dettol), disinfectants used on non-living surfaces (bleach) and antibiotics.

Broad

Spectrum of antibiotics that affect many different Gram-positive and Gram-negative species, such as tetracycline.

Narrow

Spectrum of antibiotics which are more selective, such as Penicillin which only affects Gram-positive and some GramB-negative bacteria.

Bactericidal

Antibiotics which kill bacteria, such as penicillin.A

Bacteriostatic

Antibiotics which prevent bacterial multiplication, but do not kill. Without antibiotic, bacteria will return to normal.

Transpeptidase

Enzymes which cross-link polysaccharide molecules by attaching them to side chain of amino acids. Used to form bacterial cell walls.

Penicillin

Released from penicillium fungus when growth is inhibited and it is under high stress. Bactericidal and narrow spectrum. Small enough to penetrate right through murein, and can enter some Gram-negative bacteria via porins. Prevents the cell wall from being build, causing the cell to burst via osmosis.

DD-transpeptidase

Enzyme used in cell wall synthesis in bacteria. Inhibited by penicillin, causing the cell wall to be broken down via hydrolysis, along with it’s precursors. Weakens the cell wall, and the cell eventually lyses due to osmosis.

Tetracycline

Produced by the Streptomyces fungus. It is broad spectrum and bacteriostatic. Used from conditions from acne to anthrax. Diffuses and is pumped into bacterial cells, where it binds to small (30S) ribosome subunits and blocks tRNA attachment in the second position, the A site, preventing new amino acids from being added. A reversible effect, making it bacteriostatic.

MRSA

Methicillin-resistant Staphylococcus aureus. Resistant to penicillin and all it’s derivatives, and is treated with vancomycin. Resistant to multiple bacteria.

Innate

Immune system that consists of natural barriers that resist infection, such as the skin, microbiota, mucus and cilia of respiratory passages, blood clots and inflammation.

Keratin and collagen

Part of the skin epidermal cells that makes it waterproof, and the part in connective tissue that makes the skin tough, respectively.

Inflammation

Part of the innate immune system, which causes increased blood flow towards the site of infection with large numbers of phagocytic cells, allowing capillaries to heal and a higher temperature which is unfavourable to microbes.

Adaptive

Type of immune system where a specific response is created to each antigen, provided via lymphocytes from stem cells in the bone marrow.

Humoral

Response of the adaptive immune system where antibodies are produced via the maturation of B lymphocytes in the spleen and lymph nodes, which divide making plasma cells, which produce antibodies, and memory cells.

B lymphocytes

Part of the humoral response. Mature in the spleen and lymph nodes. Receptors on cell membranes respond to foreign antigens, and they divide to make plasma cells and memory cells.

Memory cells

Made by both B and T lymphocytes when they divide. Remain dormant in circulation, waiting for the same antigen is encountered to divide. Lessen over time, meaning some diseases require booster vaccines.

Plasma

Part of the humoural response. Cells created by the division of B lymphocytes, which then create antibodies. These bind to two antibodies, causing them to agglutinate (clump together).

Antibody

Part of the humoural response. A Y shaped glycoprotein known as an immunoglobulin. Has a quaternary structure - four polypeptides held together by disulphide bonds. The variable portions are at the end and specific to antigens, and the inner Y is heavy while outer parts are light.

Cell mediated

Response of the adaptive immune system where phagocytic and B and T lymphocytes are activated. T lymphocytes activate in the thymus gland, forming T memory, cytotoxic and helper cells.

Cytotoxic T

Part of the cell mediated response. Cells created by the division of T lymphocytes which kill pathogens with a specific antigen by lysing them. AKA T killer cells.

T helper

Part of the cell mediated response. Cells created by the division of T lymphocytes which release chemicals including cytokines, which stimulate phagocytic cells, clonal expansion and antibody creation.

T lympocytes

Part of the cell mediated response. Activated in the thymus gland. Receptors on their cell membranes respond to antigens and they divide, making T memory, T killer and T helper cells.

Cytokines

Part of the cell mediated response, and released by T helper cells. Stimulate phagocytic cells, such as macrophages, B and T lymphocytes to undergo clonal expansion and B lymphocytes to create antibodies.

Clonal expansion

Stimulated by cytokines. When B and T lymphocytes divide repeatedly into genetically identical cells, forming a large population of cells specific to one antigen, which differentiate into various lymphocyte classes.

Primary

Immune response with a short latency period where macrophages consume foreign antigens, followed by T helper cells detecting the antigen and secreting cytokines and B plasma cells secreting antibodies for 3 weeks to subside symptoms of infection.

Macrophage

In the primary immune response, these engulf the foreign antigen, or cell/virus to which it is attached and incorporate the antigenic molecules into their own cell membrane, a process known as antigen presentation and making macrophages a type of antigen-presenting cell.

Antigen presentation

Process where macrophages incorporate the antigenic molecules of the foreign molecule engulfed into their own cell membrane, making them a type of antigen-presenting cell.

Secondary

Immune response that relies on memory cells. After a short latency period, memory cells undergo clonal expansion faster than before. Antibodies are made quicker and more concentrated, and remain at high concentrations in the circulation for longer, preventing any symptoms developing.

Active

Immunity when the body makes its own antibodies, which is long lasting as it produces memory cells. This can be stimulated by infection or a vaccine.

Vaccine

Can be made by antigens isolated from pathogens, attenuated (reduced in effect) pathogen strains, inactivated or killed pathogens and inactivated toxins. These are recognised as non-self, and the body produces it’s own antigens.

Booster

A type of vaccine sometimes given, as memory cells can decreased if not re-exposed to a pathogen. An example is tetanus.

Passive

Type of immunity where the body receives antibodies from another individual, such as via the placenta or breast milk. Also can be given as antibody injections.

Ig replacement therapy

AKA antibody injections. Given when rapid resistance is needed, such as rabies infection, or immunocompromised individuals, such as those with HIV, become sick. This is short lived as the body will respond with an immune response to these antigens.

Immunogenic

Able to produce an immune response. Vaccines are more successful if antigens are highly this, as more specific antibodies are made.

Serotype

Another term for antigenic type. If there are multiple, vaccines are more difficult as each type requires a new vaccine.