microbio exam 4 cards 3/19 (up to before second line innate)

what is a virulence factor?

it is a component of a pathogen that allow it to cause disease better

what does it mean when a pathogen has a highver pathogenicity due to virulenc factors?

this means the pathogen has a higher capacity to infect and cause disease

what are common ways that virulenc factors help a pathogen?

• helps it multiply faster

• helps it avoid the immune system

• helps it attach or enter tissues

describe if cytolytic toxins are exo or endo and explain what they do to immune cells

these are exotoxins and they form pores in the cell membranes of immune cells causing them to lyse.

name 4 virulence factors for pathogens

capsules
toxins
flagella
iron-binding proteins

explain what a PAI or pathogenicity island is

these are specialized genetic sequences that are clustered in a bacterial genome to help encode for virulence factors

name the three different adherence factors from the slides

proteins, adherins, fimbriae

what is the characteristic of fimbriae

hair-like proteinfilaments on a cell surface

what is the characteristic of adherins

proteins or sugars that directly bind to host receptors

describe coagulase (what does it do and what secretes it)

it forms fibrin clots and blocks white blood cells. secreted by Staphylococcus aureus

describe streptokinase

dissolves fibrin clots

describe hyaluronidase and how it helps pathogens

this digests hyaluronic acid and it works by digesting hyaluronic acid in the extracellular membrane to allow microbes to get past it

describe collagenase and how it helps pathogens

digests collagen which is strongly present in the basement membrane.

how can a microbe get past the extracellular matrix AND the basement membrane?

the microbe needs both hyaluronidase and collagenase to get past both layers

describe leukocidin

this is a type 2 exotoxin that lyses specifically white blood cells

describe hemolysin

this is a type 2 exotoxin that lyses both red and white blood cells to interfere with host immune responses

what does it mean to have toxemia

this means there are toxins present in the bloodstream

what is toxic shock syndrome (and what bacteria causes it)

this is when type 1 exotoxins release superantigens which cause the immune system to overreact and output an immune response exponentially greater than normal. This is caused by bacteria Staphylococcus aureus and Streptococcus pyogenes

what is a type 1 exotoxin?

this is an exotoxin that acts on the surface of a cell using MHCII or T cell receptors in order to cause cytokine storms or systemic inflammation. these usually cause other things to kill it rather than directly killing it

what is a type 2 exotoxin?

these are toxins that directly damage the cell membranes and lyse them

what are type 3 exotoxins?

these are toxins that have an A and B subunit. The B subunit allows entry and binds to specific receptors on the cell while the A subunit goes in and disrupts the cell

what type of exotoxin is diphteria?

type 3 exotoxin

are exotoxins made by gram positive bacteria, gram negative bacteria, or both?

both

what is an endotoxin and what gram bacteria is it from?

endotoxins are mainly lipopolysaccharides that are released from gram negative bacteria membranes dissolving

what can endotoxins cause?

they can cause inflammation and cytokine production and at higher doses, septicemia

what are the three lines of immune defense

1. innate barrier defense

2. innate cellular and molecular defense

3. adaptive defenses

is innate or adaptive immunity the immunity you are born with?

innate

what is the window of response from exposure to an infectious agent for innate immunity?

0-96 hours

what is first line innate immunity?

innate barriers

what is the second line of innate immunity?

innate cellular and molecular defenses

what are divisions of first line innate immunity

mechanical, physical, and chemical

what are examples of mechanical defenses?

tears and saliva flow, peristalsis, urine flow, menstrual flow, respiratory cilia

why is skin such a good physical first line innate immunity defense?

it is dry, salty, acidic, and built of dead cells

are lysozymes physical or chemical first line innate immunity defenses? what do they break down?

lysozymes are chemical first line innate immunity. they break down peptidoglycans

what are AMPs?

antimicrobial peptides that bind to microbial membranes and lyse them through mechanisms like pore formation

what happens if the first line of defense fails?

the microbes invade the host and cause infection

the lymphatic system drains what and transports it where?

it drains excess interstitial fluid and proteins from body tissues and transports it to the blood

what happens in the primary lymphoid tissues? what are the primary tissues

immune cell development and maturation occurs here and the primary tissues are the thymus and bone marrow

what happens in the secondary lymphoid tissue and what is part of it

activates lymphocytes and filters lymph and collects antigens. the appendix, spleen, and peyer’s patches are all part of it

define hematopoiesis

the development of erythrocytes

what do all pluripotent blood cells start as?

pluripotent stem cells

where does hematopoiesis occur?

in the bone marrow

what are the immune cell lineages?

granulocytes
monocytes and macrophages
dendritic cells
lymphocytes

what are granulocytes? (name each one as well)

these are immune cells with granules in their cytoplasm. these are neutrophils, basophils, eosinophils

how do neutrophils defend?

they envelop pathogens through phagocytosis and use reactive oxygen species and antimicrobial enzymes from their granules to kill them. they also form NETs or neutrophil extracellular traps to contain pathogens from spreading.

how do neutrophils relate to pus forming?

dead neutrophils with the dead microbes and cellular debris help form pus

explain NETs

these are DNA, histones, and antimicrobial proteins that are sent out from neutrophils to trap and kill extracellular pathogens.

what are basophils related to and how do they defend?

basophils are related to allergenic responses. they defend by releasing histamine during inflammation from their granules.

where are basophils and mast cells located?

basophils are in the blood and mast cells are in the tissue

what are eosinophils related to and how do they defend?

eosinophils are related mainly to parasitic worms and allergic reactions. They amplify inflammation during allergies and for parasitic worms they bind to its surface and release toxic proteins that destroy its surface to kill it.

how do monocytes and macrophages differ and connect?

macrophages are monocytes that have moved into the tissue from the blood.

what can monocytes cause in a person?

they can cause sepsis

what are dendritic cells and where are they found?

these are professional antigen presenting cells that are found in tissues.

how do dendritic cells function?

they will move between the surface and find antigens and bring them to the closest lymph node. these cells then activate naive T cells and start an adaptive immune response

what is the main characteristic of lymphocytes?

these are cells that migrate to the lymph nodes to scan for antigens presented by dendritic cells

describe B cell lymphocytes

these are lymphocytes that produce and secrete antibodies that look for specific antigens

what is an antibody?

these are proteins with two heavy and two light chains that have specific foreign counterpart that binds with it called an antigen

describe T cell lymphocytes

these are lymphocytes that mature in the thymus to attack

what is the difference between CD4+ T cells and CD8+ T cells?

CD4+ T cells are helper cells that direct and initiate immune responses using cytokines. CD8+ T cells are cytotoxic cells that directly kill virus or cancer infected cells.

what are Natural Killer cells? (include the cell lineage: granulocyte, dendritic, etc)

these are lymphocytes that kill the body’s own cells if it’s infected with a virus or cancer

are NK cells innate or adaptive?

these are innate

are T cells innate or adaptive?

adaptive

if both NKs and CD8+ t cells attack virus and cancer cells, how are they different?

NK cells are looking for cells without MHC class 1 while CD8+ cells look for cells presented to them with specific antigens from MHC class 1 molecules

are NK cells first or second line innate and are they fast or slow?

they are second line defense and are fast