Unit 5 Combined Set: Microbial Symbiosis, Virulence, Immunology & Epidemiology

rhizosphere

complex microbial ecosystem including plant roots and surrounding soil

phylosphere

leaves of plants and the complex microbial ecosystem that covers them

leghemoglobin

oxygen carrier protein that is found on nitrogen fixing root nodules of legume plants. It functions to sequester oxygen, protecting nitrogenase.

mycorrhizae

Fungi that grow with the roots of a plant in a mainly symbiotic relationship

biostimulation

Method to clean up toxic chemicals by providing additional nutrients for existing bacteria to grow

bioagumentation

Method to clean up toxic chemicals by adding bacteria to a spill site

chemolithotrophic

the use of inorganic reduced compounds for energy

A. fischeri

bacterium that has the ability to act as an bioluminescent and often forms mutualistic symbioses with invertebrates

microbiota

microorganisms that make up a particular area, habitat, or within the body

Helicobacter pylori

bacterium that was found to be the causative agent of stomach ulcers

prebiotics

non-digestible food additives used to promote growth of good bacteria

probiotics

living organisms that have scientifically been proven to improve health when consumed or administered

gnotobiotic

term to describe animals that lack normal microbiota or all together are "germ free"

Clostridium difficile

bacterium that can cause serious complications such as colitis and highly resistant to antibiotics

dysbiosis

microbial imbalance on or inside the body that can cause a disruption in normal function

endosymbiont

organism that lives to mutual benefit within the body or cells of another organism

Rhizobia

nitrogen-fixing bacteria that are commonly found in the soil, mainly found in root nodules of leguminous plants

pathogenicity

the ability of a parasite to inflict damage on a host

virulence

the degree to which a pathogen inflicts damage (usually measured as an LD50) The lower the LD50 - the more deadly the disease is...

septicemia

blood poisoning giving rise to a systemic infection from bacteria or other toxins that can lead to septic shock, inflammation, and or death

indirect transmission

infections that spread from when an infected individual sneezes or coughs allowing transmission to occur through air droplets or fomites.

superantigens

toxins that over-stimulate the host immune response which can lead to shock and death

adherence

enhanced ability of microbes to attach to host tissues

LD50

estimate of virulence by measuring the lethal dose of a pathogen to kill 50% of a population

fomite

an object that can likely carry infections such cloths, utensil, furniture, etc.

coagulase

bacterial enzyme that aids in clotting to protect bacteria from immune system responses

cytolytic toxins

toxins that degrade cytoplasmic membrane integrity which results in cell lysis and death

adhesins

cell surface components of bacteria that aid in adhesion to other cells or surfaces an is a virulent factor

opportunistic infection

infection caused by organisms that do not normally cause disease in healthy hosts

protein A

virulence factor used by some bacteria to bind to the Fc portion of antibodies to prevent phagocytosis by the immune response

infection

when a microorganism is established and growing in a host, could be or could not be harming the host

bacteremia

presence of bacteria in blood, usually transient, no replication

direct transmission

Transmission of an infection in which there is physical contact between an infected individual and an susceptible individual

Clostridium tetani

bacterium that is responsible for causing tetanus

hyluronidase

a tissue destroying enzyme that breaks down host tissues

pathogen

microbial parasite that inflicts damage in a host and causes disease

Mackaness experiment

Experiment that demonstrated that serum could transfer some, but not all immunity

negative selection

T cells that bind strongly to self antigens are either silenced or deleted

MHC Class I proteins

found on all nucleated cells. present internal antigens to CD8+ T cells so that the cell can be targeted for destruction by T cells.

superantigen

interacts with constant regions of MHC and constant regions of T-cell receptors, activating many T-cells in a short period of time

positive selection

T cells that recognize MHC peptides are retained

MHC Class II proteins

found on professional antigen-presenting cells (ie dendritic cells, macrophages, B cells). Presents the internalized antigen to CD4+ T cells, activating helper T cells to receive T cell help.

CD4+ T cell

Release cytokines, increasing the inflammatory response from white blood cells.

CD8+ T cell (Cytotoxic)

T cells that directly kill cells which display foreign antigens. Cell-to-cell

perforin

a protein released by CD8+ T cells that destroys targeted cells by creating pores in their membranes

granzyme

a protein released by CD8+ T cells that induces programmed cell death in targeted cells

Th17 cells

Th cells that recruit neutrophils

Treg cells

develop upon T cell activation with a dendritic cell and self antigen. Help reduce the immune response.

incidence

the number of new cases of a disease in a given area over a given period of time

prevalence

the total number of new and existing cases in a given area at a giventime

endemic

diseases that are "normal" in a specific given area, typically at low levels

epidemic

diseases that infect an unusually high number of people

pandemic

diseases that spread worldwide

epidemiology

the study of the occurrence, distribution, and determinants of health and disease in a population

surveillance

observation, recognition, and reporting of diseases as they occur at every level.

reportable diseases

diseases that have the potential to become an epidemic or diseases that are atypical. medical clinics are required to provide information on them to the CDC.

outbreak

a large number of cases in a given area at a given time

chronic infection

infections that have long disease stages.

acute infection

infections that proceed and are resolved rapidly

mortality

incidence of death in a population from a particular infection

morbidity

quality of a disease that refers to the incidence of the disease, including fatal and nonfatal diseases.

Disability-Adjusted Life Year (DALY)

quantitative measurement of disease burden in terms of lost years due to disease, disability due to disease, and premature death.

balanced pathogenicity

a pathogen that balances virulence with transmission opportunities-- isn't too virulent, as to kill the host before being passed on, which wouldn't be favorable to the survival of the pathogen.

zoonotic diseases

diseases that do not normally use humans as hosts, and are therefore often quite virulent to humans

herd immunity

resistance of a group to an infection due to a high proportion of the group being immune

common source epidemic

usually arises from contamination of water or food, has a rapid increase and a rapid decrease

host to host epidemic

people spread the disease to other people. the disease shows a slow, progressive rise and a gradual decline

R0 value

the number of expected secondary cases of a given disease from a single case. the higher it is, the more infectious the disease is.

R value

observed reproductive number, which can be altered by infection control measures and herd immunity. bringing it down to under one will help eliminate a disease.

innate immunity

non-inducible mechanisms to recognize and destroy pathogens or their products

cytokines

proteins produced by immune cells to communicate with themselves, nearby cells, or distant cells

extravasation

movement of a cell from the blood vessel to the surrounding tissues

dolor

One of the 4 cardinal signs of inflammation, defined as pain

opsinization

C3b coats a target so it can be engulfed by phagocytes easier

granzymes

enzyme associated with cell death

cytokine storm

a positive feedback loop with pro-inflammatory cytokines that can be lethal

membrane attack complex (MAC)

end result of complement activation, directly attacks pathogen by poking holes (polymerizing C9)

interferons

cytokines produced by virally infected cells that protect nearby cells from viral attack

phagocytes

immune cells that engulf bacteria

calor

one of the 4 cardinal signs of inflammation, defined as heat

pyrogen

a cytokine that can cause a fever (IL-1 typically)

rubor

one of the 4 cardinal sings of inflammation, defined as redness

chemokine

cytokines that draw immune cells towards the site of an infection

tumor

one of the 4 cardinal signs of inflammation, defined as swelling

chemoattractant

serves as a signal to draw more immune cells towards infection site

complement (C')

set of proteins that circulate in the blood and activate to act as a first line of defense mechanism against pathogens

interleukins

type of cytokine related specifically to the immune system, are typically numbered

perforin

protein produced by NK cells and cytotoxic T cells that pokes holes in a target's membrane

monocytes

precursor cell to macrophages and dendritic cells

granulocytes

leukocytes with granules including cells like neutrophils, eosinophils and mast cells

macrophages

engulfs bacteria at site of infection

dendritic cells

presents antigen from pathogen to T cells

PAMPs

pathogen associated molecular patterns, like flagellin, LPS, peptidoglycan

C3H/HeJ mice

has a point mutation in TLR4 gene so do not respond to LPS

neutrophils

contain granules for pathogen killing, are recruited to bacterial infection site

eosinophils

elevated levels are associated with parasitic infections

antigen

molecule seen as "not self" by immune system

leucocidins

cytotoxin used by some bacteria to kill leukocytes

mast cells

associated with allergies, release histamine because they bind to IgE on with their Fc receptors

phagosome

membrane bound vesicle containing an engulfed bacteria