CSCC BIO 2215 Exam 4

Define hypersensitivity

an immune response that damages tissue

Define allergen

the antigen to which allergic individuals are sensitive

Define allergy

hypersensitivity reaction due to a normally harmless, environmental substance

What are the four types of hypersensitivities?

Type I: Immediate IgE-mediated

Type II: Cytotoxic

Type III: Immune complex-mediated

Type IV: Delayed cell-mediated

What antibody classes and lymphocytes are involved in each type of hypersensitivity?

type I: IgE antibodies

type II: complement system and antibody dependent cellular toxicity

type III: IgG or IgM antibodies

type IV: T cell receptors

Type I: what three steps occur upon first exposure to the antigen?

1. B-cell Activation: B cell binds to allergen and is activated by helper T cell

2. Proliferation, class-switching and differentiation: the B cells differentiate into IgE-producing plasma cells and memory cells.

3. Sensitization: Fc portions of IgE antibodies bind to mast cell receptors

Type I: what three steps occur upon secondary (or subsequent) exposure?

1. Cross-linking of cell-bound IgE: cross-linking by allergen causes the mast cell to degranulate.

2. Degranulation and release of mediators: histamine and other mediators are released.

3. Allergy symptoms: symptoms of allergy include sneezing and runny nose.

How does immunotherapy treat Type 1 hypersensitivities and lead to desensitization?

by injecting someone with extremely dilute concentration of allergen.

allergen gradually increased over time and individual gradually become less sensitive.

How does omalizumab treat Type 1 hypersensitivity?

by binding to the Fc portion of IgE, which blocks the attachment to mast cells and basophils

What are the four main blood types in which antigens are associated with each blood type?

Type A - A antigens

Type B - B antigens

Type AB - A antigens and B antigens

Type O - no antigens

How does the Rh factor cause hemolytic disease and pregnant women?

the basis of the disease is when there is incompatibility of Rh factor between the mother and child

Rh antibodies form in Rh- mothers who are pregnant with Rh+ fetuses

What does RhoGAM do?

Destroys fetal Rh+ RBCs that have crossed the placenta

What are some common causes of Type III hypersensitivities?

bacterial, viral, protozoan infections and also from inhaled dust, bacteria, injected medications.

Explain the process of Type IV hypersensitivities.

delayed hypersensitivities that are caused by T cell responses that are slowly developing an antigen specific T cell response

What are some examples of Type IV hypersensitivities?

contact dermatitis, tissue damage, positive tuberculosis skin test, poison ivy

How does the TB test work?

injected right beneath skin, 48-72 hour incubation

+ = hard red area, - = no reaction

What markers are used as the basis of tissue graft/organ transplant rejection?

MHC class 1 differences between the donor and recipient

What is an autoimmune disease?

A malfunction in the immune system that results in destruction of self antigens (auto-antigens)

What are some examples of tissue/organ specific and widespread autoimmune disorders?

Organ specific: Thyroid disease

Widespread: Rheumatoid arthritis, lupus

What are Primary immunodeficiencies?

inherited disorder of immune system (B, T, NK, phagocytes, complement system)

example: Selective IgA deficiency (antibody deficiency), DiGeorge syndrome (lymphocyte deficiency), and Chronic Granulomatous Disease (GCD, phagocytic deficiency)

What are secondary immunodeficiencies?

results from environmental factors, like malignancies, pregnancy, increased age, etc.

example: syphilis, leprosy, malaria, AIDS

What type of microbial infection causes Streptococcal Pharyngitis (Strep Throat)?

bacterial infection of the upper respiratory tract

strep throat is an acute infection

What is the name of the causative agent of strep throat?

Streptococcus pyrogenes

What are the symptoms of strep throat?

- sore, red throat with patches of pus

- difficulty swallowing

- fever

- enlarged, tender, lymph nodes, and neck

What violence factors does Streptococcus pyrogenes have?

- M protein, important adhesion an anti-phagocytic factor

- structural components of outer cell wall/capsule allow evasion of host defenses

-Hyaluronic acid capsule anti-phagocytic factor and host mimicry

What is the root of transmission for strep throat?

Airborne droplets from coughing or sneezing

Which type of microbial infection causes pinkeye, earaches and sinus infections?

bacterial infections

All three infections are acute

What is the name of the causative agents for pinkeye, earache, and sinus infection?

- Haemophilus influenza (G- bacilli)

- Streptococcus pneumoniae (G+ diplococcus)

- Mycoplasma pneumoniae

- Streptococcus pyrogenes

- Staphylococcus aureus

What are the symptoms for pinkeye earache, and sinus infections?

Conjunctiva - teariness, redness, swelling, pus

Otitis media - severe earache, fever, vomiting, and ruptured eardrum possible

Sinusitis - facial pain/pressure, headache, nasal discharge, malaise

What virulence factors do pinkeye, earaches and sinus infections have?

strains that infect the conjunctiva have adhesions that allow them to attach firmly to the epithelium

What is the route of transmission for pinkeye, earaches, and sinus infections?

Sinusitis and otitis media - usually proceeded by nasal infection, probably spread via eustachian tube

Conjunctivitis - poorly understood

What type of microbial infection causes diphtheria?

bacterial infection of the upper respiratory tract

Diphtheria is an acute infection

What is the causative agent of diphtheria?

Corynebacterium diphtheriae

What are the symptoms of diphtheria?

- mild sore throat

- slight fever

- extreme fatigue

- malaise

What virulence factors does Corynebacterium diphtheriae have?

release diphtheria toxin (powerful B exotoxin) -> gene is carried by specific lysogenic bacteriophage

What is the route of transmission for diphtheria?

Spread by air, acquired via inhalation or from fomites

What type of microbial infection is the common cold?

viral infection of the upper respiratory tract

The common cold is an acute infection

What are the causative agents of the common cold?

99 serotypes of rhinovirus, plus coronavirus, and adenovirus

What are the symptoms of the common cold?

- malaise

- sore throat

- runny nose

- cough

- hoarseness

What virulence factors does the common cold have?

rhinoviruses bind to and infect nasal epithelial cells and may cause the cells to die or slough off

What is the route of transmission for the common cold?

airborne droplets inhaled, touching eyes

What type of microbial infection is Adenoviral Pharyngitis?

viral infection of the upper respiratory tract

adenoviral pharyngitis is a latent infection

What is the cause agent of adenoviral pharyngitis?

more than 50 antigenic types of human adenoviruses

What are the symptoms of adenoviral pharyngitis?

- runny nose

- ever

- sore throat

- gray-white pus on pharynx and tonsils

What virulence factors does adenoviral pharyngitis have?

adenoviruses attached to and enter epithelial cells, and can remain infectious in the environment for long periods of time

What is the route of transmission for adenoviral pharyngitis?

respiratory droplets, fecal-oral

What type of microbial infection is pneumococcal pneumonia?

bacterial infection of a lower respiratory tract

pneumococcal pneumonia is a acute infection

What is the causative agent for pneumococcal pneumonia?

Streptococcus pneumoniae

What are the symptoms of pneumococcal pneumonia?

- sudden rise and temperature and shaking chill

- sputum becomes pinkish, or rust colored from blood

What virulence factors does streptococcus pneumoniae have?

-A capsule (unable to cause infection without this), which helps adherance (this allows it to bind to pharyngeal epithelial cells and colonize most people)

-Produces a cytotoxin (pneumolysin) that induces cell lysis (that causes fluid to move into the lungs)

What is the route of transmission for pneumococcal pneumonia?

around 30% of healthy people carry the bacteria in their throat, risk of infection increases when the host defense is impaired

What type of microbial infection is klebsiella pneumonia?

bacterial infection of the lower respiratory tract

klebsiella pneumonia is an acute infection

What is the positive agent of klebsiella pneumonia?

Klebsiella pneumoniae

What are the symptoms of klebsiella pneumonia?

- repeated chills

- Production of bloody, gelatinous sputum

What virulence factors does klebsiella pneumoniae have?

The capsule interferes with the action of the complement system component C3b

The bacterium produces a specific siderophore with a very high affinity for iron, allowing it to "steal" from the host cells

What is the route of transmission for klebsiella pneumonia?

contracted via inhalation, contact, or medical equipment (like a ventilator)

What type of microbial infection is Mycoplasmal pneumonia ("walking pneumonia")?

bacterial infection of the lower respiratory tract

Mycoplasmal pneumonia is an acute infection

What is the causative agent of mycoplasmal pneumonia?

Mycoplasma pneumoniae

What are symptoms the of walking pneumonia?

includes fever, malaise, sore throat, and excessive sweating

onset is gradual, generally mild

What virulence factors does mycoplasma pneumoniae have?

bacterial attachment damages the respiratory epithelium, causing the ciliated cells to slough off

What is the route of transmission for walking pneumonia?

aerosolized droplets of respiratory secretions

What type of microbial infection is Pertussis (Whooping Cough)?

bacterial infection of a lower respiratory tract

Whooping cough is an acute infection

What is the causative agent of whooping cough?

Bordetella pertussis

What are the symptoms of whooping cough?

3 stages:

1. Catarrhal stage (information of mucous membranes): one to two weeks of signs resembling URI, most contagious stage

2. Paroxymal stage (repeated sudden attacks): frequent bursts of violent, uncontrollable coughing, dry but severe; small blood vessels in eyes rupture, tongue protrudes, neck veins stand out. Forceful inhalation of air: "whoop" sound in children, susceptible adult. Vomiting and seizure may occur.

3. Convalescent stage: not contagious, coughing decreases.

What virulence factors does Bordetella pertussis have?

- Fimbriae and adhesions for attachment: stop silly reaction, triggering, immune response and cell death

- release three toxins critical to disease: PTx (AB toxin) -> increases mucus, decreases phagocytosis. Adenylate cyclase -> kills leukocytes. Tracheal cytotoxin -> fever, kills ciliated epithelial cells

What is the route of transmission for pertussis?

Droplet transmission

What type of microbial infection is tuberculosis?

bacterial infection of the lower respiratory tract

Tuberculosis is a chronic infection

What is the causative agent of tuberculosis?

Mycobacterium tuberculosis

What are the symptoms of tuberculosis?

- slight fever

- weight loss

- night sweats

- persistent cough

- often blood streak sputum

What virulence factors does mycobacterium tuberculosis have?

Cording factor and cell wall lipids

acid-fast organism, strict aerobe that grows very slowly

What is the route of transmission for tuberculosis?

airborne/droplet nuclei

What type of microbial infection is influenza?

viral infection of the lower respiratory tract

Influenza is an acute infection

What is the causative agents for influenza?

influenza A in orthomyxovirus family

What are the symptoms of influenza?

- headache

- fever

- sore throat

- muscle pain (peeks in 6 to 12 hours)

- dry cough develops and worsens over a few days

What virulence factors does influenza have?

8 segments of ssRNA, glycoprotein spikes embedded in envelope: hemagglutinin agent (HA) and neuraminidase antigen (NA).

HA: attachment

NA: release and spread

What is the route of transmission for influenza?

inhalation of droplets, or transferred to eyes, ears, nose from contaminated fomites

What are the functions of the upper respiratory tract?

Warm, filter, and moisten incoming air

1st and 2nd line of defense that protects the lower respiratory tract

What are the functions of the lower respiratory tract?

3rd and 4th line of defense present in lower to respond quickly if needed

How are the middle ear and nasal cavity connected?

eustachian tube

Which part of the respiratory tract is abundant in microbiota?

upper respiratory tract covered with normal flora (nasal cavity, nasopharynx, and pharynx)

Which areas of the respiratory tract are free of microbiota?

conjunctiva commonly have no normal flora

Lower respiratory tract: usually microbe free

What is the mucociliary escalator?

layer of mucus moved by cilia lining the respiratory tract that traps bacteria and other particles and moves them away from the lungs

Why are infection infections in the lower respiratory tract more serious?

because they affect the airway and lungs

For Streptococcal Pharyngitis: What complications can be caused if left untreated?

acute rheumatic fever (ARF), and Post-Streptococcal Glomerulonephritis (PSGN)

What is pinkeye?

conjunctivitis, inflammation of the eye surface

What is sinusitis?

inflammation of the sinuses

What is otitis media?

inflammation of the middle ear

How do microbes enter/reach the middle ear and cause otitis media?

spread through the eustachian tube, and builds up fluid/pus

Why is pinkeye, sinusitis, otitis media so common in small children?

children have smaller anatomy, a developing immune system, and poor hygiene practices

Diphtheria: What are pseudo-membranes?

Tough layers of dead cells and debris accumulated on an epithelial surface

For colds: Why are there no vaccines for colds?

because such a large number of immunologically different viruses cause colds.

Pneumonia: Why is Mycoplasmal pneumonia called walking pneumonia?

Because it is the mildest form of pneumonia, it doesn't cause you to go to the hospital

Which type of pneumonia is the most fatal?

Klebsiella pneumonia

Whooping Cough: Why is this disease more commonly found in infants?

because they are the most vulnerable due to their immature immune systems

Tuberculosis: Why is TB so hard to treat?

because the bacteria is an acid fast bacillus with a protective waxy capsule coating that makes it difficult to treat - it can stay alive in "suspended animation"

How do we test for tuberculosis?

Tuberculin Skin Test (TST)

Why do we not vaccinate for tuberculosis in the US?

because it causes TST to read positively

What is an antigenic drift in influenza?

minor mutations in the HA and NA genes, often a singular amino acid, responsible for seasonal influenza

What is an antigenic shift in influenza?

uncommon, concurrent infection that allows mixture of 8 RNA segments.

completely new strain of influenza, can lead to pandemic

Influenza: Explain how the surface antigens change and what effect that has on the antibodies your body makes

the NA and HA antigens will mix and match their different types to create new strands of influenza

This means that your body may have antibodies for the sub type of NA, but not HA, so you would still become sick due to you not having any antibodies that recognized that subtype