MICRO 201 PENN STATE FINAL EXAM

Ability to live in a .......... is a MAJOR virulence factor

Phagocyte / They are obligate intracellular pathogens live in them, cannot be detected by antibodies

Beta cells differentiate into....

plasma and memory cells, plasma B cells produce antibodies

What does IgG stand for?

Immunoglobulin G, most common antibody,

The variable region of IgG (antibody) is.....

Antigen specific, the properties of the antibodies and what antigen they will attack are found in this region

Infection

Growth of an orgranism on or within a host

Pathogenicity

Ability of an organism to cause disease

Opportunistic PAthogen

Causes disease only in the absence of normal host resistance mechanisms

Virulence

Measure of the pathogenicity of the organism

Measuring virulence: ID50

Infectious dose that is seen 50% of the time. The amount of an agent required to infect exactly half of the tested hosts

Measuring virulence: LD50

Infectious dose that is fatal 50% of the time. The amount of agent required to kill exactly hald of the tested hosts

Exception to LD50

Highly virulent pathogens show little differene in the number of cells required to kill 100% of the population compared to just 50%

Stages of virulence in order

Exposure: to pathogen

Adherence: binding to host

Invasion: entering host

Colonization and growth: production of virulence factors

Path 1: toxicity: toxin effects

Path 2: invasiveness: further growth

all lead to -> disease

Attentuation

The decrease or loss of virulence

Toxicity

Organism causes disease by use of toxin meant to inhibit or kill host cell. Toxins can travel to cites within hosts not inhabited by pathogen.

Invasiveness

Ability of a pathogen to grow in host tissue at densities that inhibit host function. CAn cause damage w/o producing toxin

Toxicity vs Invasiveness

toxicity: phage producing toxins that cause the damage, the organism itself may not be actually causing issues but its products are

Invasiveness: Organism is actually inside of the host, living and growing. The direct growth of this organism can cause disease.

True or False: Pathogens utilize only Toxicity or invasiveness to cause pathogenicity

False, Many bacteriums use a combination of toxins, invasiveness, and other virulence factors to enhance pathogenicity

Activation of Beta cells leads to....

Clonal Expansion

Memory B cells allow rapid and strong production of antibodies after ...... exposure to antigen

Second

Primary Response to a pathogen has mostly ..... the second exposure mostly has...

IgM -> memory cells generated , IgG (due to memory cells) -> memory cells develop into plasma cells

How antibodies help: Agglutination

Sticking bacteria in one big clump, one phagocyte can clear them out

How antibodies help: Opsonization

Coating antigen with antibody = easy grip by phagocytes (lube it up)

How antibodies help: Neutralization

Blocks adhesion of bacteria and viruses to mucus = prevent binding receptors/no active binding

How antibodies help: Inflammation

Disruptuon of cell by complement, reactive protein that attracts phagocytic and immune cells

Activation of the Complement

Antibody binds to cell and punches hole in cell wall

Membrane Attack Complex (MAC)

What actually makes a hole in the activation of the compliment

Clonal Deletion

Removes self-reactive T-cells and antibodies, clearing out cells that would hurt you

Strep Throat

a case of molecular mimicry, 50% viral and 50% Streptococcus pyrogenes, if strep is due to pyrogenes -> you must NOT let the immune system clear it. The same antibodies that attack the bacterium will attack your heart valve too

What does cross reactive mean

Attacks pathogens and body

Allergies

People with allergies produce IgE

Being too clean especially as a kid is bad because it can result in more allergies, bone marrow thansplant can resolve allergies. THEY ARE A MATTER OF CROSS LINKED ANTIBODY MOLECULES

True or false: pregnant women should not clean out littler boxes

True, There are chemicals in cat pee that hurt the fetus. Toxoplasmosis -> messes up the placenta

Booster Shots increase...

IgG in the system up until the second exposure

Lady Mary Montegue (1689 - 1762)

Learned about practice of virulation to prevent smallpox.

Edward Jenner

Coined word vaccination

Epitope

Portion of a protein that elicits B-cells to make antibodies, usually 8-10 AA in length

What happens if clonal deletion does not occur?

Can result in autoimmune diseases, if non self if mistakenly deleted / it can result in a "hole"

IgE

binds to mast cells, dimerizes them and that signals mast cells to release histamine. Important in getting rid of helminths (worms and parasites)

Treatments for Allerigies

Antihistamines: block histamine receptors

Thymus processing eliminates....

98-99% of T lymphocytes

Poison Ivy

Delayed type hypersenstivity reaction

History of immunization

Smallpox, virulation came from Lady Montegue and proven by Edward Jenner. Weakened form of a pathogen can be used to raise a protective immune response w/o causeing disease. Vaccination = vacca -> cow

Specific immunity: Natural exposure: Active

Normal experience is how you develop immunity

Specific immunity: natural exposure: passive

From parents (womb, breast feeding)

Specific immunity: artificial: Active

Vaccines (antibodies injected into you)

Specific Immunity: artificial: passive

Transplants (blood, marrow)

Tetanus

Clostridium tetani, toxin causes muscles to contract. Require booster shot 10/yr to help prevent.

Cryptosporidium parvum

Protozoan, single eukaryote, THE MOST IMPORTANT WATER BORN PATHOGEN IN THE DEVELOPED WORLD, resistant to chloring treatment

What is a reservoir in relation to a pathogen?

It's the way in which you would find it in nature, could be humans, animals, water, etc.

Carriers

People who carry pathogen but do not have disease

Staph aureus is a .... repitaory infection and Streptococcus penumonie is a .... resporatory infection

Upper / Lower

Types of exposure

Direct contact, vectors, soil, H20, food

Pasteur proved that ....... give things like good wine and bread

Good organisms like yeast

PAsteurization

Heating to destroy all undesirable organisms w/o destroying the product

Loxiella burnetelli

Q fever, #1 food borne pathogen, lots of pathogens are found on row or undercooked meat

Stanley Falkow (1934-)

Father of molecular microbial pathogenesis, genes and proteins must be involved in pathogenesis

Adherence

Diseases have to stick to host tissues before they can invade them -> capsules prevent phagocytosis -> sticky and hard to break

Adherence is usually a..... and ...... fit

Lock and Key

UPEC

Ueropathogenic E. coli

UTI

Urinary tract Infection, Capsule, flagella, biofilm , anf fimbrae

......... protein binds to .................. host glycoproteins on epithelial cells of the .........

FimH / mannosylated / bladder

What can we take to prevent adherence of UTI's?

Mannose, so the FimH just binds to that instead of the bladder walls, basically just a decoy

Invasion

Pathogens produce enzymes that enhance virulence by breaking down or altering host tissue to provide access to nutrients

Protecing the Pathogen

Interfering with normal host defense mechanisms.

Iron

Bacteria have to work hard to get iron in the environment. Iron is present in very tiny amounts. Bacteria and fungi synthezise and secrete iron chelaters.

Siderophores

Iron bearer

Gram negative bacteria versus humans

Gram - want more iron whereas humans work to keep iron low

Transferin

Iron binding protein, moves iron in and out of cells, keep serum levels low

If you have a mouse infected with 100000 pathogens and one with just 100 pathogens (this is their LD50), what happens if you give them an iron injection?

Their LD50s decrease by a 100x change. So only 1000 will cause the disease in the first and only 1 will cause the disease in the second.

TonB system of E coli

A novel type of ACTIVE transport across the unenergized outer membrane. TonB is a virulence factor for UPEC. New target for antibiotics.

What happens if you block the TonB system? Why don't gram + have a tonB system?

The gram - are not effective able to interact with FepA (infectious factor) and that will eventually kill the cell. Gram + have one membrane, so they don't need TonB

Toxins

Exotoxins (action at a distance) - cytolitic, AB, superantigen

Endotoxins: part of bacterium

Exotoxins

Proteins released from the pathogen cell as it grows

3 Major types of EXOtoxins

Cytolitic, AB (2 subunit), superantigen

Cytolitic Toxins

Work by DEGRADING cytoplasmic membrane cytoplasmic membrane integrity, causing host cell lysis and death.

Cytolitic toxins that lyse red blood cells are called

Hemolysins, ex is Staphylococcal alpha-toxin

AB Toxins 2 subunits

A + B subunits, work by binding to host cell receptors via subunit B and transferring damaging agent, A, across cell membrane Ex: Clostridium botulinium

Mediucal uses for botulism toxin

Relaxes overactive muscles. Botox

tetanus Toxin medical uses

Excites nonactive muscles

Botulism

soil bacterium, easy way to contract is from not properly canned foods, spored germinate in anerobic environment

Superantigens (SAGS)

Pouring gasoline on the immune response fire, cause acute-system-wide inflammation that damages tissues and organs ex: s. aureus

John Snow (1813)

Father of epidemiology Found that cholera is spread through water. Cholera was a pandemic at the time and now.

Cholera enterotoxin is encoded on a temperate bacteriophage

Toxin co-regulated pillus is found on a "pathogenicity-island". Both toxin and pillus are virulance factors.

PAthogenicity ISland

REgions of a chromosome that harbor lots of different virulence genes. These virulence genes are surrounded by removable IS sequences that make them transposable elements.

Endotoxin

Lipopolysaccharide portion of cell envelope of the gram - bacteria elicits an imflammatory response. GENERALLY LESS TOXIC THAN EXOTOXINS

Vaccines prevent bacterial....

Capsule formation

Most tuberculosis infections are....

Latent/dormant, they hide in the system and then they come out when characteristics are right. Stays walled off in the lungs

Humans have evolved lipocalins, which are

A human made proteins that bind and deactivate the enterochelin formed by bacteria that tries to steal iron.

E.coli, to combat lipocalins, now produce....

Strains of enterochelins decorated with glucose that the body can't recognize.

Cytokine storm

attack self tissue, can be prevented with clonal deletion

Potable

safe to drink, not accessible in third world countries. Most who drink water become carriers/

A cholera outbreak in Haiti was due to...

Un workers who were carriers

Herd Immunity

The ability of the group to resist disease. When the herd has immunity, infection can only be transmitted to the susceptible.

CoEvolution of host and pathogen (Rabbit in austraila example)

Takes a lot of time. First the rabbits are highly susceptible. then they start becoming resistant. That leads to the virulence of the phage to decrease too. Myxoma is the disease in rabbit population.

What happens if there is no herd immunity?

Anyone who is susceptible will become infected

Ro is...

The number of people that one person with the disease can infect.

If Ro = 50 for X and Ro = 2 for Y, which is more infectious?

Ro = 50

Animal REservioirs

Zoonoses

Smallpox Eradiacation

No Carrier State: humans are only reservoir, an infected person always shows symptoms

Transmission is exclusively human -> human. Vaccine was extremely effective.

Enterotoxins

Variety of exotoxins active in the gut

Cytotoxic T-cells can recognize........

Host cells with pathogens inside