Damage (4)

Does speed matter in immune response and why?

Yes because it is a race between pathogen replication and spread, and mobilization of host response

What three things cause symptoms?

Immunopathology, inflammation, and direct action of pathogen

What is the leading cause of death for children?

Diarrhea

How does diarrhea cause death?

It depletes body fluids and causes extreme dehydration

What are most diarrhea-associated deaths caused by?

Unsafe water, inadequate sanitation, and insufficient hygiene. Mostly spread via fecal-oral route through contaminated water

What are the causes of diarrhea?

Microbial, the mechanism for shedding, and host-induced to get rid of infectious agent

What are skin rashes often a result of?

Immune activity

What are mechanism that allow pathogens to cause direct damage?

Cytopathic, acid production, damaged macrophage releases cytokine, etc.

How is HIV an example of direct pathogen damage?

Directly lyses CD4+ T cells, causing immune collapse

How are respiratory viruses examples of direct pathogen damage?

They kill epithelial cells, allowing secondary bacterial infections

How are worms an example of direct pathogen damage?

They cause mechanical damage by obstructing the bile duct

What are exotoxins?

Proteins that are produced by gram positive or negative bacteria that alter a function or kill host cell

What are some examples of exotoxins?

Cytolytic enzymes (disrupt membrane), receptor-binding proteins, and superantigens

What is an endotoxin?

LPS which is a part of bacterial cell wall, induces immunopathology, and usually released when bacterial cell dies

What are a common target of vaccines?

Toxins

What are different targets that toxins are classified by?

Intracellular targets, cell surface, and extracellular matrix

What are toxins that modulate intracellular targets?

Exotoxins, Type III Cytotoxins, and Type IV to VII Cytotoxins

What are toxins that act at the host cell surface?

Endotoxin (LPS), membrane-damaging toxins, and superantigens

What are the toxins that act on extracellular matrix?

Exoenzymes, like Hyaluronidase, Collagenase, and Elastase (break components of connective tissue), DNases, and Streptokinase (breaks clot)

What are characteristics of tetanus toxin?

Causes painful muscle contractions, lockjaw, prevented with vaccine, and treated with antitoxin and antibiotics

What are the characteristics of botulinum toxin?

Caused by Clostridium botulinum, results in muscle weakness, inhibits excitatory neurons, treated with antitoxin

What are characteristics of Cholera Toxin?

Produced by vibrio cholerae, affects ion channels, efflux of ions cause water loss and acute diarrhea

What are mechanisms of action that toxins can be classified by?

Enzymatic lysis, pore formation, inhibition of protein synthesis, and hyperactivation

What are the characteristics of Diphtheria Toxin?

Produced by C. diphtheriae, inhibits protein synthesis causing cell death

What is immunopathology?

Damage caused by the host's immune response to infection, contributes to many symptoms, helps host survive

What part of a bacterial cell wall is an endotoxin?

LPS

What is LPS composed of?

Lipid A, core polysaccharide, and repeating O-polysaccharide

What receptor binds to endotoxin?

TLR4

What can be induced by high levels of endotoxin?

Septic shock (driven by TNF)

What are symptoms of inflammation?

redness, swelling, pain, and heat

What can an influx of neutrophils cause?

Puss, damage of extracellular matrix, staphylococcal abscess

What are characteristics of staphylococcal toxic shock syndrome?

Produced by Staphylococcus aureus, mediated by superantigen TSST-1, and death caused by hypovolemic shock leading to multiorgan failure

What toxins and superantigens can cause STSS?

SpecA and SpecC

What is necrotizing fascitis?

Flesh eating disease caused by streptococcus pyogenes

What are consequences of overactive adaptive immune responses?

Prolonged infections can result in hypersensitivity