Benefits the host.

microbes in human gut (enterobacteria)

aid in digestion

train immune system

Microbe benefits, no help or harm to host usually

e.g. staphylococcus epidermis (lives on skin and eats sluffed off cells)

Microbe benefits, host is harmed

Types:

Primary pathogens

Opportunistic pathogens

Commensal pathogens

Chronic pathogens

Primary pathogens

Cause disease in otherwise healthy host

e.g influenza

Opportunistic pathogens

only cause disease when the health of thehost is compromised.

e.g. pathogenic fungi- pseudomona aeruginosa (cystic fibrosis, burns susceptible)

lie dormant for a while, eventually cause disease

e.g. mycobacterium tuberculosis

single celled

binary fission for replication (replicate DNA, split)

Cell wall (peptidoglycan)

No nucleus

single circular chromosome

obligate intracellular pathogen/parasite(need another cell to live)

enclosed by a membrane/protein coat

variety of nucleic acids for genome:

dsDNA, dsRNA, ssRNA, ssDNA

eukaryote

cell wall (chitin)

heterotroph (all rely on braking down organic matter)

eukaryotes:

protozoa

helminth (worms)

1. microorganism should be found in organisms suffering from disease, but not in healthy organisms

2. Microorganisms must be isolated from infected organism and grown in pure culture.

3. implant into healthy organism

4. should be able to reculture organism from the infected individual.

Woolsorter's disease (bacillus anthrasis)

1. Spores in environment 

2. spores enter host

3. spores germinate, spread

4. bacteria fight immune system, cause disease

5. host dies spores re-enter environment 

1. reservoir

2. attachment entry

3. replication and spread

4. fight immune system

5. exit

 all components that fight a pathogen the same way every time (no memory)

1st line of defense

all components capable of learning.

host takes advantage of unique aspects of pathogens to destroy them.  

e.g. viral pathogens (RNA replication process)

skin: epidermis is outermost (continually renewing)

outermost cornified dead layer is barrier to most organisms

can enter through cuts in skin, digestive system, lungs, use of additional organisms, hair follicles

Mucous membranes:

continuous secretion of mucous (keeps pathogens away from cells, eg goblet secreting cells in villi of pancreas)

cillia: wave particles out of lungs and up esophagus.

stomach: low pH, degrading enzymes

1. anti-microbial peptides

2. anti-microbial proteins (larger, 3ary struct)

AKA defensins

short +charged, amphopathic

forms pores in cell walls of bacteria, lyses

selective for bacteria

larger, tertiary structure

e.g. lysozyme (degrades peptidoglycan), albumin

RNAase (contra viral genomes)

lactoferrin: soaks up iron from bacteria (need iron to grow)

1. heat stable (antibodies), due to disulfide linkage

2. heat labile (compliment)

one protein is cleaven into two, one of which cleaves another, etc.

used in clotting

results in inherant amplification

study it!

uses antibodies

mannose/fructose pattern on bacterial surface is bound by manosbinding lectin (MBL)

triggers compliment cascade

MBLs recognize pathogens based on surface protein

originate in bone marrow, resides in blood

gives rise to macrophage or dendritic cell

tissue resident

long-lived

part of liver but originate in bone marrow

"Street sweepers" eat everything not supposed to be there 

short-lived, live in blood

respond to infection

contain granulocyte (dense vesicle of protein, anamirobial peptides, lysozyme)

Also called Polymorphonuclear cells (PMN)

lobed nucleus allows neutrophil to squeeze into tight places

nucleation (initiation of polymerization)

actin dimer is hardest to form, after that its down hill

actin:atp is active form, actin:adp is inactive form

Arp2/3 is a nucleating protein, binds 3 actin polymers (overcomes rate limiting step)

Postive feedback: Arp2/3 binds to side of actin chain and initiates new chain, "webbing effect"

phagocyte can bind to surface antibodies or compliment.

ARP2/3 activated near binding site, membrane curves around bacteria, additional receptors bind.

rapid polymerization, envagination

Guanine nucleotide exchange factor

Rho-lipid modification

activates Rho:GTP

1. protein: calprotectin

2. DNA chromatin forms extracellular trap

Neutrophil (esp. contra bact)

eosinophil (contra parasites)

basophils (allergy)

Mast cells (in tissue, release histamine)

causes inflammation:

capillaries swell, allow neutrophils to spueeze through tissues, diffusion of necessary chemicals

high increasein histamine.

treat with epinephrine (contraction of vasculature) eg epipen.

professional antigen-presenting cells

work with adaptive immune system

macrophage

dendritic cell

Pathogen associated immunostimulant

any molecule made by pathogen that is not made by the host and which the host uses to detect infection

e.g small molecules, repeating patterns (PAMPs)

inflammation

recruitment of phagocyte

phagocytosis

PAI 

unique tRNA for initial methionine start codon in bacterial transcription

lipopolysaccharides (LPS)

important PAI in gram negative bacteria:

the outer leaflet of the outer membrane of gram negative bacteria is composed of LPS

variation in LPS structure among bacteria, but all share common core.

PAI

anchored in membrane, giant polymer protrudes through cell wall

fx: adherence, negatively charged

serves as PAI

bacteria has  CpG motife.  In euk, cytosine methulated in fifth position, bacteria is normal.

used to recognize viruses

normal Euk RNA: mRNA, tRNA, rRNA

primarily single stranded

Double stranded in viruses (reovirus)

immune system recognizes dsRNA

protein flagellin ("motor" structure)

TLR5 recognizes flagellin

molecule released from one cell population that have an effect on themselves and/or other cell pop.s

cytokine important for growth and differentiation of the immune system.

cytokine, made by macrophage, endothelial cells

results in inflammation, stimulates phagocytosis

by itself is responsible for gram negative sepsis

cytokine, produced by macrophage, epithelial, endothelial cells

PMN chemotaxis (signal to neutrophils)

Interferon gamma (IFN gamma)

primarily made by T-cells (adaptive immune system)

signal to activate macrophage (wants signal for T cell swallows bacteria but doesn't kill cell outright until it gets IFN gamma from T cells)

protein with lectin domain, binds carbohydrate on PMN, forming weak connection.

selectin anchored to actin filament in cytosol.

during blood flow, neutrophil rolls along endothelial surface.

"purple lightning" 

cutaneous hemorrhages and necrosis in kids and youth

group B streptococcus

(gram stain and shape)

tremonema

leptospira

borrelia

syphilis

spirochete

can't gram stain

can't culture

STD

chronic infection (takes decades to progress to tertiary)

general serology

specific serology (antibodies for Lipoprotiens)

chronic infection

obligate aerobic

non gram staining

acid fast (stains mycolic acid)

facultative intracellular pathogen

high lipid content, waxy and hard to penetrate

obligate intracellular

persistant chronic infections

non gram staining

can be stained with silver

human reservoir common

STD and ocular infection

EB: extracellular (infectious)

RB intracellular (replicating)

no cell wall (no gram stain, no cell wall antibiotics)

shape changs

smallest bacteria

growth is fastidious and requires media with sterols

slow growth

obligate intracellular

polymerize actin

geographically diverse

no culture

zoonotic