MicB 3301 Final Review

• food/water borne pathogens
• S. typhimurium used by cults to try to sway votes (bioterrorism)

• number of pathogens that will kill 50% of an experimental group of hosts
• lower LD50=more virulent

• 1. host contact/entry
• 2. replication
• 3. spread
• 4. cellular injury
• 5. host immune response.
• 6. clearance, persistance, or death of host

large mass/fusion of cells; multinucleated. forms in response to viral infection

• specific site of infection (cell/tissue/organ)
• receptor dependent

• H=hemaglutinin=attachment
• N=neuraminidase=spread; cleaves host lipids and glycoproteins

• 1. block cytokine (interferon) synthesis
• 2. breakdown complement proteins
• 3. block production of complement proteins
• 4. block antigen processing of MHC export
• 5. antigenic variation (i.e changing the a.a. sequence in virion spikes)

• antiviral cytokines: important in viral resistance during early stages of infection
• destroy viral mRNA
• shut down viral translation
• stimulate CTLs and NKs

• capsules
• pili
• M protein

• virulence factor that clots sera, forms a shield that protects pathogens from phagocytosis
• ex) S. aureus

• Virulence factor that binds plasminogen and digests fibrin clots. Allows movement and spread
• ex) Staphylococcus, Streptococcus

• virulence factors that lyse RBCs and make Fe available to bacteria
• ex) staphylococcus, streptococcus, E. coli

• virulence factor that breaks down collagen and allows bacterial spread
• ex) Clostridium sp.

• virulence factor that cleaves IgA into Fc/Fab fragments
• ex) Streptococcus pneumoniae

• bacteremia=presence of bacteria in the bloodstream
• septicemia=growth/division of bacteria in the bloodstream

• 1. adhesion of bacteria to host cell
• 2. block adhesion of phagocytes to bacterium

• 1. Resist the complement system: cleave c5a, lengthen LPS, capsules
• 2. avoid specific immune responses: capsules, antigenic variation, IgA proteases
• 3. avoid phagocytosis: capsule, proteins that block adherence (M protein), leukocidines, coagulase
• 4. survival inside phagocytic cells: phagosome escape or resistance to ROS and NO, prevent phagosome-lysosome fusion

• 1. Listeria monocytogenes
• 2. Legionella pneumophila
• 3. Mycobacterium tuberculosis

• intracellular pathogen
• uses host cell actin polymerization
• doesn't enter extracellular space or illicit an immune response

• intracellular pathogen
• inhibits phagosome-lysosome fusion

• intracellular pathogen
• inhibits phagosome-lysosome fusion
• can escape phagosome to cytoplasm

• microbial communities attached to a surface and covered by a polysaccharide matrix
• protected from immune response and antibiotics
• produce virulence factors under QS control

• infection of the inner ear
• Streptococcus pneumoniae
• recurring infections due to biofilm protection from antibiotic treatment

Pseudomonas biofilms in the lungs

Staphylococcus or Enterococcus biofilms on heart valves

• 1. Membrane disrupting
• 2. AB exotoxins
• 3. superantigens
• 4. specific host site exotoxins

• membrane disrupting exotoxin that forms pores which cause host swelling and lysis
• ex) hemolysins release Fe
• ex) leukocidins kill macrophages

• membrane disrupting exotoxin
• cleaves host lipid bilayer between head and tail, leading to instability

• exotoxins that interact with and lock MHCII receptors to TCR, which overstimulates Tcell response even in the absence of peptide
• increases cytokines and inflammation
• ex) Staphylococcus and toxic shock syndrome toxin

• transmembrane, 2 subunits
• A= toxic effect
• B= binds to target cell

• ex) Shiga toxin
• ex) E. coli O157: H7

• AB exotoxin that does not form a pore via the B subunit
• instead, it enters the host via receptor mediated endocytosis
• at ph <5, the vesicle and A and B subunits diffuse to cytoplasm
• A affects ADP ribosyl transferase, B goes back to membrane

• often AB
• enterotoxins
• neurotoxins

• specific host site exotoxins that stimulate host adenylate cyclase which increases cAMP which causes ion imbalance and H20 loss.
• ex) cholera toxin of Vibrio cholerae

• specific host site exotoxins that block the release of Ach from the neuromuscular junctions, causing flaccid paralysis because the muscle can't contract
• ex) botulinum toxin of Clostridium botulinum (used in Botox)

• inactivated toxin that still illicits the immune response
• part of vaccines

vaccine for Diptheria, Tetanus, and Pertussis

• LPS from gram (-) bacteria
• more general effects: fever, shock, inflammation
• causes: release of endogenous pyrogens, TNF
• ex) meningitis, petechia--due to gram (-) shock

• for gram (-) pathogens
• inject effectors via injectisome

needle, pore, basal body

• large, often chromosomal DNA regions of the pathogen that encode many virulence genes (often in operons)
• encodes: injectisome for TTSS
• G and C content often differs from the rest of the pathogen genome...evidence for HGT

• host cell cytoskeleton- actin
• host cell signalling- NFkB

• Enteropathogenic E. coli: cause of infantile diarrhea
• ex) Type III secretion System
• binds host cells using bundle forming pili, assembles injectisome and delivers effectors
• *one effector is Tir-Translocated intimin receptor
• Tir is presented on the host cell surface to bind EPEC intimin and serve as a docking station

• magic bullets
• selective toxicity (to germ rather than host)

Selman Waksman

• accidentally discovered penicillin
• Staphylococcus and Penicillium on same plate

• Florey
• Chain
• Heatley
• (1939)

• cidal: kills pathogen
• static: inhibits growth

• 1. Cell wall synthesis
• 2. Plasma membrane
• 3. Nucleic acid synthesis
• 4. Protein synthesis
• 5. metabolic enzymes

• betalactams (penicillin)
• Vancomycin
• Bacitracin

• Polymyxins
• Imidazole
• Nystatin

• Quinolones
• Rifampin

• Aminoglycosides (streptomycin, kanamycin)
• Tetracycline
• Macrolides (erythromycin, azithromycin)

• Sulfonamide
• Triclosan

• target PBPs (penicillin binding proteins) for transpeptidation
• transpeptidation: energy used to cross-link NAG and NAM residues with the terminal D-Ala
• penicillinase attack the beta lactam ring

• CELL WALL SYNTHESIS INHIBITOR
• glycopeptide antibiotic
• binds terminal D-Ala and prevents peptidoglycan synthesis

• CELL WALL SYNTHESIS INHIBITOR
• inhibits carrier for peptidoglycan subunits

• PLASMA MEMBRANE INHIBITOR
• disrupt lipid bilayer
• cidal against narrow spectrum gram-

• PLASMA MEMBRANE INHIBITOR
• blocks synthesis of membrane sterols
• treats athletes foot

• PLASMA MEMBRANE INHIBITOR
• binds membrane sterols
• treats Candida infections

• NUCLEIC ACID SYNTHESIS INHIBITOR
• inhibits DNA gyrase
• **synthetic antimicrobials
• ex)Nalidixic acid
• ex)Ciprofloxacin

• NUCLEIC ACID SYNTHESIS INHIBITOR
• inhibits RNA polymerase (and therefore transcription)

• PROTEIN SYNTHESIS INHIBITORS
• prevent 30S and 50S binding
• ex) Streptomycin
• ex) Kanamycin

• PROTEIN SYNTHESIS INHIBITOR
• binds 30S, distorts A site, prevents amino-acyl tRNA binding

• PROTEIN SYNTHESIS INHIBITORS
• bind 50S rRNA, block elongation
• ex) Erythromycin
• ex) Azithromycin

• METABOLIC ENZYME INHIBITOR
• metabolic analogs that inhibit folic acid synthesis
• also inhibit purine and pyrimidine synthesis

• METABOLIC ENZYME INHIBITOR
• present in plastics, toothbrushes, etc.
• binds enoyl reductase (an enzyme for fatty acid synthesis)

• ANTIVIRAL
• inhibits DNA polymerase of herpes virus

• ANTIVIRAL
• inhibits neuraminidase to prevent spread of influenza virus

highly active antiretroviral therapy

• HAART antiviral for HIV
• targets reverse transcriptase
• nucleoside analog, causes DNA chain termination

• HAART anti-HIV drug
• protease inhibitor (prevents viral assembly)

• 1. prevent access to or alter the drug target
• 2. create an enzyme to degrade antibiotic (ex. penicillinase)
• 3. Alter antibiotic (ex. phosphorylation)
• 4. efflux pumps
• 5. resistance genes from HGT

Vancomycin resistant Enterococcus

has a mecA gene which encodes mutant PBP, creates low affinity for penicillins

• Herpes family
• dsDNA, icosahedral, enveloped
• causes Chickenpox and Shingles

• attenuated (live): specific genes inactivated, activates humoral and cellular immune responses, may revert
• inactivated (killed): chemicals or irradiation, activates humoral response, requires a booster
• VLP (Virus Like Particle): noninfectious, naked, capsid (no genome) of a virus ex) Gardisil

• Measles, Mumps, Rubella
• all caused by RNA viruses
• MMR vaccine=attenuated

SHIFT: major antigenic changes, often the result of different strains resorting via a reservoir (ex. Swine flu)

DRIFT: minor antigenic changes, due to mutations in N (or H) of influenza virus (ex. seasonal changes and increases in flu outbreaks)

• 1. new antigenic influenza subtype
• 2. infects humans, and causes serious illness
• 3. spreads easily

• =arthropod-borne viruses
• insects=vectors
• ex) Yellow Fever-mosquito
• ex) West Nile Fever-mosquito and birds
• RNA flavoviruses

• hemorrhagic fevers
• ex) fruit bats and the Ebola virus (filamentous morphology)
• viral proteins cause blood clotting, interferon blocks, and hemorrhaging

zoonotic

• HIV/AIDS
• Common Cold
• Mononucleosis
• Hepatitis

• enveloped, icosahedral, RNA retrovirus
• enzymes and proteins: gp120, protease, reverse transcriptase, integrase
• life cycle: in a CD4+ Th cell, genome integrates (provirus), uses host machinery to assemble capsid
• pathogenesis: depletion of T cells and APCs (dendritic cells)

• Acquired Immune Deficiency Syndrome
• HIV infected individual with <200 CD4+ T cells per uL of blood

• Major cause of the common cold
• ssRNA+, naked, icosahedral
• >100 different serotypes

• cell-surface receptor for Rhinoviruses
• Intracellular Adhesion Molecule-1

• type of herpesvirus; cause of Mononucleosis
• infects epithelial cells and then B cells
• icosahedral, enveloped, dsDNA

Epstein Barr Virus

• 11 viral causes (2=herpesviruses, 9=hepatotropic viruses)
• inflammation of the liver

• multiple modes of transmission
• cause Jaundice, hepatitis
• treatment: vaccines, recombinant interferon therapy

• (1 of 2) viral gastroenteritis
• NSP4=viral enterotoxin that promotes fluid secretion

• (1 of 2) viral gastroenteritis
• naked, RNA
• outbreaks on cruise ships, at oscar parties

• causes polio (infantile paralysis)
• naked, icosahedral, +ssRNA
• stable in food and water
• targets motor nerve cells in spinal cord, creates paralysis
• treatement: attenuated and inactivated vaccines available

• cause of TB (intracellular pathogen)
• waxy coat/cell wall that allows identification by acid fast staining
• treatment: iconiazid and rifampin

• Streptococcus pyrogenes and Streptococcus pneumoniae
• infections of the skin, throat, lungs
• Treatment: penicillins, macrolides (erythromycin)

• necrotizing fasciitis
• Invasive Streptococcus pyrogenes infection

• Bordetella pertussis (Gram -)
• virulence factors: pili, siderophores, Ptx
• Ptx: targets adenylate cyclase (increases secretions, mucus)
• treatment: Augmentin

• Rx for Whooping Cough/Bordetella pertussis
• Amoxicillin component inhibits cell wall synthesis
• Clavalanate component impedes beta lactamases

• Haemophilus influenzae
• Streptococcus pneumoniae
• Neisseria meningitidis**

• one cause of meningitis
• gram (-): LPS->TLR4->TNF->PMNs from blood vessels
• virulence factors: endotoxin, pili, capsule

• Yersinia pestis
• 2 types: Bubonic and Pneumonic
• Bubonic: fleas spread, lymph nodes to rest of body forming bubos
• Pneumonic: humans, flu-like initially but 100% fatal if untreated
• Uses a Type III secretion system

• Borrelia burgdorferi
• stages: 1-localized, 2-disseminated, 3-late
• treatment: Tetracyclines, Penicillins

• Bacillus anthracis
• Toxin: AB but three parts
• cutaneous vs. respiratory
• Treatment: Quinolone (ciprofloxacin)

• AB but three parts:
• PA=protective antigen (B)
• EF=edema factor (A)
• LF=lethal factor (A)
• encoded on plasmid and enter cell when the three toxins associate

Concept that viruses are selfish and prevent superinfection by removing entry receptors from the cell surface once they have infected it

• Vibrio cholerae gram (-)
• cholera toxin increases adenylate cyclase, causes ion imbalance and H20 hypersecretion

• Clostridium botulinum
• botulinum toxin: prevents Ach release from neuromuscular junctions, causes flaccid paralysis and cardiac failure

• Salmonella typhimurium: causes acid stress response in stomach, activates a specific set of genes in the human GI system
• E. coli 0157:H7: carried by cattle, produces shiga-like AB toxin, that cleaves rRNA. Encoded on a temperate phage (which makes treatment difficult)

• Lactic (cheese and yogurt)
• Propionic
• Ethanolic (alcohol)

balances with glycolysis (NAD+-->NADH reduction, ADP-->ATP)

2 pyruvate-->2 lactate. NADH-->NAD+ oxidation, no ATP required

• Lactobacillus and/or Streptococcus (Starter Culture)
• "Lactic Acid Bacteria" gram (+)

• "polylactide"
• E. coli and Lactobacillus

milk--1-->curd--2-->cheese

• 1=Lactococcus starter culture and renin
• 2=ripening by microbial action (microbe varies for each type of cheese)

Propionibacterium

Penicillium roqueforti

• Brand names: Serovera, Activia, Bifantis
• Microbes: Lactobacillus, Bifidobacterium
• Benefits: compete with unwanted organisms, produce antimicrobial compounds, etc.

• Sacchromyces ferments the must (from grapes/juice)
• Leuconostoc sp. undergo malolactic fermentation (malic acid to lactic acid)

• compound that accumulates during period of nutrient limitation following active growth (aka stationary phase)
• ex) Penicillin G and other ANTIBIOTICS

Using microbes to degrade pollutants

enzyme (from microbes) to use to clean up oil spills--some microbes can use that carbon as a source of energy