response to infection Flashcards
disease definition
a condition that impairs the normal functioning of an organism
how does invaders cause disease?
number of mechanisms to protect body from invading organisms, when these mechanisms are overcome, invaders cause disease
pathogens
disease causing organisms
communicable infectious diseases
diseases that are spread from one person to another
most common pathogens that affects the body
bacteria and viruses
bacteria - structural characteristics
- cell wall
- no nucleus (prokaryotes)
- flagellum present
- DNA in the form of plasmids
majority of bacteria are…
non pathogenic
uses of bacteria
- essential to life e.g. decomposition of organic material
- industrial processes e.g. lactobacilli to make yogurt and sauerkraut
location of bacteria
live in skin & inside intestines
how does bacteria affect the body?
affect the body differently depending on the species
effects of bacteria
producing toxins & inducing allergic responses
size of bacteria
very small (microscopic) = diameter from 0.5 to 2.0 micrometers
under microscope, shape of cells is visible → used to classify
how to identify bacterium
grown on an agar player/growth medium in specific conditions → stained → viewed under microscope
viruses definition
microscopic infectious agents
virus structural characteristics
- all contain genetic material in the form of DNA or RNA (but never both)
- consist of a protein sheath surrounding a core of nucleic acid
- some also have an external lipid envelope
reproduction of virus particles
- totally dependent on living cells for reproduction
- not living things - cannot reproduce by themselves
- infect a living cell and it’s DNA/RNA induces the cell to manufacture more virus particles
- new virus particles leave the host cell → infect others
bacteriophages
viruses that infect bacteria
contagious disease
communicable disease may be spread by the transmission of pathogenic organism from one person to another
vectors with examples
intermediate host of the pathogen, e.g. fleas, mosquitoes
transmission of pathogens
- transmission by contact
- ingestion of food or drink
- transfer of body fluids
- infection by droplets
- airborne transmission
- transmission by vectors
transmission of contact
- spread of pathogen by physical contact
- direct = actually touching infected person
- indirect = touching an object that has been touched by infected individual
transmission of contact examples
skin infections, STIs
ingestion of food and drink
contaminated with pathogens
ingestion of food and drink examples
salmonella food poisoning, dysentery
transfer of body fluids
when blood or other fluids from an infected person comes into contact with mucous membranes (nose, throat, mouth, genitals, bloodstream) of another uninfected person
- via a needle stuck; break in the skin
transfer of body fluids examples
HIV, Hepatitis B and C
infection of droplets
- tiny dropped it to moisture containing pathogenic organisms are admitted when breathing, talking, sneezing or coughing
- may be breathed in by others; settle on food or utensils to be later ingested with food
ingestion of droplets examples
Ebola, COVID-19, mumps, cold, flus
airborne transmission
- moisture in exhaled droplets evaporate, most bacteria are killed, but viruses and some bacteria remain viable → cause infection when inhaled
- particles are lighter → remain viable for greater distance than those transmitted by droplets
airborne transmission examples
measles, chickenpox
transmission by vectors
- animals such as insects, ticks or mites
- some vectors transfer the pathogen directly
- some may spread the pathogen to food or water → injected (e.g. houseflies)
- Many vector-borne disease are spread by specific vector
transmission by vectors examples
malaria is spread by mosquitoes; lyme disease spread by ticks
non-specific defences
defence of the body that acts against all pathogens (innate)
specific defences
directed against a specific pathogen (adaptive)
external defences purpose
stop pathogens and foreign particles from entering
external defence examples
- skin
- mucus
- hair
- cilia
- acids
- lysozyme
- cerumen
- movement of fluid
skin
- overs outside of the body
- good at stopping entry of microorganisms (provided there are no cuts/abrasions)
- special protection at openings in skin (mouth, eyes, anus)
- normal bacteria occupy skin → pathogens find it difficult to establish
skin additional mechanisms
- sebum
- sweat
sebum
oily, waxy secretion from sebaceous glands; kills pathogenic bacteria
sweat
liquid produced by sweat glands; contains salts and fatty acids that prevent growth of many micro-organisms
mucus
Mucous membranes = epithelial tissue that secretes mucus and lines many body cavities
- Secretes mucus = slippery, stringy substance
- Traps particles → inhibits entry of microorganisms to the organs of the body
- Eg, digestive, urinary and reproductive tracts
- Irritation = Fumes; dust particles
hair
- Found in the nasal cavity and ears
- Hairs + layer of mucus = trap up to 90% of particles inhaled when breathing
cilia
hair like projections from a cell; beat rhythmically to move material across a tissue surface
- Mucous membranes lining the nasal cavity and trachea have cilia
- Beating of the cilia moves mucus (containing trapped particles and micro-organisms) towards the throat → coughed or swallowed
acids
Stomach juices are strongly acidic (HCI)
- Kills many of the bacteria taken in with food or those contained in mucus swallowed from nose or windpipe
- Vagina has acid secretions → reduce growth of microorganisms
lysozyme
enzyme that kills bacteria
- found in tears, saliva and perspiration
cerumen
cerumen = ear wax
- Protects the outer ear against infection by some bacteria
- Slightly acidic
- Contains lysozyme
movement of fluid
Eg. Urine flowing through urethra = cleansing action
- Prevents bacterial growth
- Helps stop bacteria reaching the bladder and kidneys
protective reflexes
involuntary reflexes that help protect the body from injury
1. Sneezing
2. Coughing
3. Vomiting
4. Diarrhoea
sneezing
- stimulus = irritation of the walls of the nasal cavity
- forceful expulsion of air carries mucus, foreign particles and irritating gases out through nose and mouth
coughing
- stimulus = irritation of lower respiratory tract (bronchi and bronchioles)
- air is forced out of the lungs to try and remove the irritant
- air drives mucus and foreign matter up the trachea → throat and mouth
vomiting
- contraction of abdominal muscles and diaphragm expels stomach contents
- psychological stimuli, excessive stretching of stomach and bacterial toxins = induce vomiting
diarrhoea
- irritations cause increased contractions of the muscles of the wall of the intestines → irritant removed ASAP
- material doesn’t stay in the large intestine long enough for water to be absorbed
- irritants = bacteria, viruses or protozoans
internal non-specific defences
- phagocytosis
- inflammatory response
- fever
Organisms that penetrate our external defences are attacked by…
phagocytes
Phagocytes
specialised WBC (leucocytes) that engulf and digest micro-organisms and cell debris
- eliminates many pathogens before an infection has the chance to take hold
different types of cells that are phagocytic
- Monocytes and macrophages
- Neutrophils
- Dendritic cells
Monocytes
type of leucocyte found in the blood that migrates into damaged tissues (infected or inflamed) - form macrophages
Macrophages description
large phagocytic cell; derived from monocyte
macrophages function
- some move through tissues looking for and destroying pathogens
- some are fixed; only deal with pathogens that come to them
- important in removing microbes and dying cells through phagocytosis
neutrophils description
- granulated leucocyte (granules visible in their cytoplasm)
- lobulated nucleus
neutrophils function
first cells to move into the tissue to destroy the pathogen by phagocytosis (important in killing pathogens inside cells)
neutrophils life span + death
- short life span (die after a few days)
- dead cells = pus that forms after an infection
dendritic cells description
characterised by projections from the cytoplasm
dendritic cells function
- Different from macrophages and neutrophils = function goes beyond phagocytosis
- Ability to detect, engulf and process foreign particles
- Use info about ingested particles → assist with specific immunity
Inflammation
response to damage to a tissue; involves swelling, heat, pain and redness in the affected area
- the accumulation of fluid, plasma proteins and white blood cells that occurs when tissue is damaged or infected
inflammation purpose
- Reduce the spread of pathogens, to destroy them and prevent entry of addition pathogens
- Remove damaged tissue and cell debris
- Begin repair of the damaged tissue
Four signs of inflammation
- Redness
- Swelling
- Heat
- Pain
Steps in the inflammatory shape are assisted by
proteins in the complement system produced by liver cells and macrophages
Complement system
system of proteins produced by the liver that enhance the activity of antibodies and phagocytes
how are proteins in the complacent system activated?
Proteins are inactive; when initiated → one protein activates the next and so on
inflammatory response steps mnemonic
my head hurts properly, probably from music
inflammatory response: first step
- Mechanical damage or local chemical change → specialised leucocytes called mast cells to be activated by complement proteins
- Leads to release of histamine, heparin and other chemicals into the tissue fluid
inflammatory response: second step
- Histamine increases blood flow through the are due to vasodilation
- Walls of blood capillaries more permeable → more fluid moves through capillary walls into tissue
- Increased blood flow → heat and redness
- Escape of fluid → swelling
inflammatory response: third step
- Mast cells release heparin = prevents clotting in the immediate area of injury
- Clot of the fluid forms around damaged area
- Slows the spread of the pathogen into healthy tissues
inflammatory response: fourth step
- Complement system proteins and some chemicals released by the mast cells attract phagocytes (neutrophils) → consume micro-organisms and debris by phagocytosis
inflammatory response: fifth step
- Abnormal conditions in the tissue stimulate pain receptors in inflamed area
inflammatory response: sixth step
- Phagocytes are filled by bacteria, debris and dead cells = die
- Pus formed from dead phagocytes and tissue fluid
inflammatory response: seventh step
- New cells produced by mitosis → repair of damaged tissue takes place
Fever
elevation of body temperature above 37C
pyrogens
interleukin-1, activated macrophages, dendritic and epithelial cells
what causes a fever?
- Change due to resetting of body’s thermostat (controlled by the hypothalamus) to a level higher than normal
- Reaction due to pyrogens released by WBC during inflammatory response and act on hypothalamus
how is body temp still regulated in response to heat/cold with a fever?
set point is at a higher level
how do the thermoreceptors detect body temp during a fever?
hypothalamus recognises it is lower than the new higher set point
what happens after the thermoreceptors recognise low temp during fever?
- Vasoconstriction in the skin and shivering occur
- Conserve heat and increase heat production (increasing body temp)
what happens when fever breaks
- body’s thermostat set to normal
- Person feels hot and appears flushed → skin vasodilation and sweating (bring body temp down)
how can a fever be beneficial?
- High body temp inhibits the growth of some bacteria and viruses
- Heat speeds up the rate of chemical reactions → help body cells repair themselves more quickly during disease
- May inhibit viral replication by allowing chemicals called interferons to operate more quickly
what happens if body temp goes too high?
convulsions; brain damage
- death will occur © 44.4 - 45.5C
lymphatic system consists of
- Lymph nodes - located along the length of some lymph vessels
- Network of lymph capillaries joined to larger lymph vessels
lymphatic system function
- Function = collect some of the fluid that escapes from the blood capillaries → return to circulatory system
- Important part of body’s internal defence against pathogenic organisms
Lymph nodes location and structure
- Occur at intervals along lymphatic vessels
- Contain masses of lymphoid tissue; cells are criss-crossed by a network of fibres
lymph function
Lymph entering lymph nodes contain cell debris, foreign particles and microorganisms that have penetrated the body’s external defence
what can get trapped while passing through the lymph nodes?
Larger particles (g. Bacteria) are trapped in meshwork of fibres as lymph flows through spaces in nodes
large particles that get trapped in the lymph node meshwork are
ingested and destroyed by macrophages through phagocytosis
When infections occur, formation of lymphocytes…
increase
lymph nodes become swollen and sore example
Infected finger may result in swelling and tenderness in the armpit (large no. of lymph nodes)
specific defences against disease
Directed towards a particular pathogen
If you get infected or vaccinated with chickenpox virus…
- body will make antibodies to combat the virus
- Antibodies only effective against chickenpox virus - won’t work against any other virus or bacteria
immune system composed of…
cells and proteins that protect against foreign organisms,
range of alien chemicals, cancerous and other abnormal cells
example of a cell that is non-specific
Phagocytes → able to engulf and digest
micro-organisms and cell debris
cells for specific defences against disease
b-cells and T-cells only provide protection against specific micro-organism or disease-causing substance
when t and b cells reacts it is called an…
immune response
immune response is a…
Homeostatic mechanism
immune response function
Helps to deal with the invasion of micro-organisms and foreign substances enter the body → restore to normal conditions
key cells involved in immune response
- lymphocytes
- B-cells
- T-cells
b and t cells are produced in… and end up in…
produced in bone barrow and end up in lymphoid tissue
how do t cells mature
Half of cells produced by bone marrow → go to thymus
Mature into T-cells before being incorporated into lymphoid tissue
how do b cells mature
Half mature in the bone marrow → become B-cells
Become part of lymphoid tissue
lymphoid tissue location
Most lymphoid tissue is in lymph nodes
- Also occurs in spleen, thymus gland and tonsils
what happens after b cells mature
Develops into either plasma cell that produces antibodies or a memory cell
what happens after t cells mature
Can differentiate into a no. of different kinds of cells that are involved
in cell-mediated immunity
Humoral or antibody-mediated immunity
- Involves the production of special proteins called antibodies by B-cells
- Circulate around the body and attack invading agents
Cell-mediated immunity/response
- Due to T-cells
- Involves the formation of special lymphocytes that destroy invading agents
antigen
- Any substance capable of causing the formation of antibodies when introduced into the tissues → causing a specific immune response
- Triggers both antibody and cell mediated immunity
self-antigens
Molecules produced in person’s own body doesn’t cause IR
non-self antigens
Foreign compounds that trigger IR by being recognised by receptors on B and T cells
how are self-antigens and non-self antigens differentiated in the body
Immune system becomes programmed before birth to distinguish between self-antigens and non-self antigens → only attacks non-self antigens
Antibodies shape
Y-shaped specialised protein
antibodies
Substance produced in response to a specific antigen; combines with the antigen to neutralise or destroy it
how are antibodies produced
Produced by plasma cells in response to a non-self antigen → combines with that antigen → forms an antigen-antibody complex
* Antigen molecules have specific active sites with a particular shape
* Antibody has the complementary shape > allowing two molecules to fit together like a key in a lock
* Each antibody can combine with only one particular antigen
what protein group does antibodies belong to
Belong to a group of proteins = immunoglobulins
* Represented by Ig
* Five classes that vary in structure = IA, IqD, IdE, laG and IgM
antigen-presenting cells
Phagocytic cells that digest pathogens and present the antigen to lymphocytes; include dendritic cells and macrophages
how do antigen-presenting cells present the antigen?
They:
- Detect the presence of a non-self antigen
- Engulf the antigen
- Digest the pathogen, producing small fragments that move to the surface of the cell
- Present the antigen to the lymphocytes
antibody mediated immunity works against…
bacteria, toxins and viruses before they enter the body’s cells; also against red blood cells of a different blood group than the person.
cell mediated immunity works against…
transplanted tissues and organs, cancer cells and cells that have been infected by viruses or bacteria; also provides resistance to fungi and parasites.
antibody mediated immunity steps
- Antigen-presenting cells recognise, engulf and digest pathogens, displaying the antigen on their surface.
- Antigen-presenting cells reach lymphoid tissue and present the antigen to lymphocytes.
- Helper T-cells are stimulated by antigen-presenting cells, which release cytokines.
- Specific B-lymphocytes are stimulated, enlarge and divide, undergo rapid cell division.
- Most new B-cells develop into plasma cells, which produce antibodies and release them into blood and lymph.
- Antibodies combine with the specific antigen and inactivate or destroy it.
- Some of the new B-cells form memory cells
cell mediated immunity steps
- Antigen-presenting cells recognise, engulf and digest pathogens, displaying the antigen on their surface.
- Antigen-presenting cells reach lymphoid tissue and present the antigen to the lymphocyte.
- Helper T-cells are stimulated by antigen-presenting cells, which release cytokines.
- Specific T-lymphocytes are stimulated, enlarge and divide, undergo rapid cell division.
- Most new T-cells develop into killer T-cells or helper T-cells, which migrate to the site of the infection.
- Killer T-cells destroy the antigen, while helper T-cells promote phagocytosis by macrophages.
- Some sensitised T-cells form memory cells
b cell receptors
- Lymphoid tissue contains 1000’s of types of B-cells
- Each has a receptor for a particular antigen > capable of responding to a specific antigen
- When antigen-presenting cell presents the antigen to the specific B-cells → cells activated
what happens after antigen is presented to helper T cells
release of cytokines
cytokines
- small proteins that are released in response to antigens; act as
messengers in the IR- Cause helper T-cells to clone themselves > release different cytokines > activate B-cells
what do memory cells do?
Spread to all body tissues to allow the response to occur more rapidly should the antigen enter the body again
plasma cells function
secrete specific antibody capable of attaching to the active site of the antigen
Primary response
- First exposure to antigen
- Slow response → days to build up large amounts of antibodies
- Time for B-cells to multiply and differentiate → plasma cells and secrete antibodies
- Declines after level of antibodies reached peak
secondary response
- Second/subsequent exposure to same antigen
- Response faster → memory cells recognise the antigen more quickly
- Plasma cells are able to form quickly
- Antibody levels in body plasma rising rapidly to higher level that lasts longer
- Antigen has little opportunity to exert a noticeable effect on body = no illness
Types of T cells
- Killer-cells (cytotoxic T-cells)
- Helper T-cells
- Suppressor T-cells
Killer-cells (cytotoxic T-cells)
- migrate to the site of infection and deal with invading antigen
- Attach to the invading cells → secrete chemical that will destroy antigen
- Then go in search of more antigens
Helper T-cells
- Bind to antigen on antigen-presenting cells → stimulate secretion of
cytokines that:- Attract lymphocytes to infection site → sensitised and activated → intensifies response
- Attract macrophages to infection site → can destroy antigens by phagocytosis
- Intensify phagocytic activity of macrophages
- Promote the action of killer T-cells
Suppressor T-cells
- Act when the immune activity becomes excessive/infection dealt with successfully
- Release substances that inhibit T and B cell activity → slowing down IR
Immunity
resistance to infection by invading micro-organisms, the ability of the body to recognise foreign substances, and destroy them
how are the presence of memory cells important?
Presence of memory cells → body to respond quickly to deal with invasion before disease occurs
Natural immunity
occurs without any human intervention
Artificial immunity
produced by giving a person an antigen that triggers an IR; or giving them antibodies to an infecting antigen
Natural and artificial immunity can be either
passive or active
Passive immunity
When a person receives antibodies produced by someone else
- Individuals body played no part in the production of antibodies
natural passive immunity
Naturally
- antibodies pass from mother → placenta → fetus (or through breast milk)
artificial passive immunity
Artificially when person is injected with antibodies to combat a
particular infection
- Done when a person is exposed to pathogens that cause serious disease eg. Tetanus, rabies
- Immunity can be established rapidly
- Short-lived (lasts until antibodies are broken down→excreted)
active immunity
Results when the body is exposed to a foreign antigen > makes
antibodies in response to that antigen
does passive or active immunity last longer and why?
active immunity lasts longer than passive → presence of
memory cells
natural active immunity
develops from having the disease and recovering
artificial active immunity
develops from an injection of the antigens associated with the disease (artificial active immunity)
Immunisation
programming the immune system to respond rapidly to infecting microorganisms; developing immunity
Vaccination
artificial introduction of antigens of pathogenic organisms
vaccines have the ability to
produce the appropriate antibodies is acquired without the person having to suffer the disease
vaccine
antigen preparation used in artificial immunisation
types of vaccines
- live attenuated vaccines
- inactivated vaccines
- toxoid vaccines
- sub-unit vaccines
live attenuated vaccines
- Living attenuated microorganisms have reduced virulence (reduced ability to produce disease symptoms)
- Immunised person doesn’t contract the disease; but manufactures antibodies against the antigen
live attenuated vaccines use examples
Eg. Polio, tuberculosis, rubella, measles, mumps
inactivated vaccines
- Contain dead microorganisms
- Produce an immunity that is shorter lasting than immunisation using LA microorganisms
inactivated vaccines use examples
Eg. Cholera, typhoid and whopping cough
toxoid vaccines
- Cases where bacteria produce their effects in humans by liberating toxins - not necessary to use the bacteria for immunisation
- Toxins produced by the bacteria can be inactivated → when injected they don’t make the person ill
- Inactivated toxins = toxoids
toxoid vaccines use examples
Eg. Diphtheria, tetanus
Sub-unit vaccine
Fragment of organism can be used to provoke Immune response
sub-unit vaccine use examples
Eg. HPV and Hepatitis B
recombinant DNA use in vaccines
- Insert certain DNA sequences from the pathogen into harmless bacterial cells
- Chosen DNA sequence causes the production of antigens characteristic of the pathogen
- Vaccination with harmless bacterium → immunity against pathogen
an approach to making pathogens less virulent
modify characteristics of the pathogen by slightly changing the DNA in the microorganisms cell→ making pathogen less virulent
most common method of vaccination
injection via syringe
when do vaccinations start
after 6 weeks of age
why are vaccines given after 6 weeks of age?
- Child’s blood contains antibodies from it’s mother via placenta and breast milk
- If given earlier than weeks, antibodies from mother will eliminate antigens
- 6 weeks gives newborn time for immune system to be activated
Antibody levels from the primary response following first dose will…
decline
why shouldn’t a second dose be take too soon
antibodies present in blood will eliminate vaccine material before B-cells can be activated
Use of vaccines in mass immunisation programs
eradicated or greatly reduced incidence of certain diseases
use of Smaller scale immunisation programs
prevent possibility of serious
outbreak of highly infectious disease
- Reduce the chance of disease in most susceptible individuals → increases immunity of population
herd immunity
occurs when high proportion of ppl in a population are immunised that those who aren’t immune are protected
problems with immunisation programs
- As incidence of infectious diseases declines > ppl become
complacent- Risk of vaccine vs risk of contracting the disease
a factor to consider with vaccinations
Inability to be vaccinated due to health issues
Inability to be vaccinated due to health issues
- Allergic reactions
- May occur from the medium in which the vaccine is cultured
- Eg. Many flu vaccines are manufactured in fertilised eggs → if allergic to egg protein they may react
- Preservatives
- Chemicals used as preservatives
- Beliefs that these preservatives can affect the NS
social factors with vaccinations
- Ethical concerns with the use of animals to produce vaccines
- Ethical concerns with the use of human tissue to produce vaccines
- Ethical concerns with informed consent
- Ethical concerns with testing on animals
- Availability
Ethical concerns with the use of animals to produce vaccines
- Viral vaccines require host tissue (as viruses can only be replicated in living cells)
- Eg. Influenza virus cultured in chicken embryos
Ethical concerns with the use of human tissue to produce vaccines
- Using human tissue avoids problems of cross-species infection from possible unknown viruses
- Eg. Rubella vaccine manufactured using cultured human cells obtained from human foetuses
Ethical concerns with informed consent
Trialing vaccines in developing countries → use in populations with low standards of education → ppl aren’t fully aware of the risks → exploitation
Ethical concerns with testing on animals
- Prior to clinical trials in humans, vaccines tested on animals to identify potential
problems - Legislation exists to limit the way animals can be used
- Mice commonly uses
social factors: availability
Vaccines aren’t always readily available in all areas
cultural factors vaccination
Religious beliefs
- Religious that rely on faith healing/healing through prayer
- Methods used to produce vaccines may contradict religious beliefs → non-participation in immunisation program
economic factors vaccination
- Cost of vaccine
- May be too expensive
- Commercialisation
- Interests of commercial vaccine production may affect it’s use
antibiotics
Drugs used to fight infections of microorganisms
what can’t antibiotics be used for and why
Cannot be used to treat viral infections
- Viruses are not living cells → do not metabolise
antibiotic
Each antibiotic is effective for only certain types of bacterial
infection
- Testing often carried out prior to antibiotics being prescribed
first antibiotic
- First antibiotic = penicillin
- Mould was able to stop the growth of Staph bacteria
how do antibiotics work
Works by preventing the synthesis of the walls of the bacterial cells → inhibiting the reproduction of bacteria
why has effectiveness of antibiotics reduced
many bacteria developed resistance to it
Other antibiotics interfere with…
- Protein synthesis in the cells of the target bacteria
- Synthesis of the cell wall
antibiotic types
- bactericidal antibiotics
- bacteriostatic antibiotics
Bactericidal antibiotics
- Kill bacteria by
- changing the structure of the cell wall or membrane
- Disrupting action of essential enzymes
Bacteriostatic antibiotics
- Stop bacteria from reproducing
- Disrupting protein synthesis
broad spectrum antibiotics
Affects many types of bacteria
narrow spectrum antibiotics
Effective only against specific types of bacteria
duration of defence: antibiotics vs vaccines
antibiotics: short lived
vaccines: long lasting
antibiotic resistance
Widespread use → some bacteria have evolved and become
resistant to antibiotics
- Multiple drug resistance = resistance of some strains of bacteria to most available antibiotics
- Caused by overuse of antibiotics in medicine and agriculture
how to slow antibiotic resistance
- Developing new classes of antibiotics
- Genetically engineer bacteria to disable antibiotic resistant genes
antivirals
- Drugs used specifically to treat viral infections
- No treatment for common ailments such as colds, chickenpox
why is it hard to find drugs that will treat viral infections
- The way viruses replicate makes it difficult to find drugs that will treat viral infections
- Host cell produces new virus particles, any drug that interferes with the virus replication is likely to be toxic to the host
- Research aimed at identifying viral proteins that can be disabled by specially designed chemicals
Common antivirals that inhibit development of virus
- Zovirax for herpes (coldsores)
- interferons for Hep B and C
Recombinant vaccines
vaccine produced through recombinant DNA technology
first vaccine for human use using recombinant DNA
hep B
Recombinant DNA and vaccines - Hep B vaccine
- Gene for surface antigen on the virus is isolated → added to a plasmid
- Plasmid introduced into a yeast cell
- When yeast cell divides, new cells contain the plasmid with the gene for the antigen
- Gene allows the yeast cells to produce the antigen protein which can be collected and purified
virulence
the severity or harmfulness of infectious diseases
physical barriers of body
barriers which physically block a pathogen from entering your body
e.g. skin, mucous membranes, cilia
chemical barriers of body
make the body surfaces inhospitable to pathogens
e.g. lysozyme, acidic secretions (cerumen, vaginal secretions)
