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MCB50 - Unit 2 - Coggle Diagram
MCB50 - Unit 2
Vaccine
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Attenuated vaccine
Advantages:
• Self-replicating
• No adjuvant
• Less expensive
• More effective at presenting MHC I antigens, stimulating CTL production
Disadvantages:
• Can become more virulent if virus mutates
• Live virus requires cold storage
• Unstable once thawed
Examples: OPV, measles, mumps, rubella, varicella zoster vaccine (VZV)
Response-eliciting component: live, but weakened, form of the pathogen. Are modified to replicate poorly or cause minimal disease.
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Inactivated vaccine
Examples: Influenza, Hepatitis A, Pertussis, IPV
Response-eliciting component: Whole, killed, non-replicating organism/toxin inactivated by chemicals, heat, or irradiation
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DNA vaccine
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Response-eliciting component: DNA encoding target antigens is delivered into cells using a vector (LNP)
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Advantages:
• Strong, long-lasting immune responses
• Safe, low risk of adverse effects
• Can be rapidly designed and produced
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mRNA vaccine
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Response-eliciting component: Lipid nanoparticles containing the gene of interest that has been cloned into mRNA.
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Pathogen
Bacteria
Sexually transmitted
Chlamydia trachomatis
How they cause disease: many different strains that can cause STD or conjunctivitis. Disease is associated with the immune response to inflammation
Replication location: Intracellular (macrophages, DCs, epithelial cells)
Immune response: IgG, IgA, Th cells, CTLs
Immune evasion: antigenic variation of surface proteins, antigen masking using unreactive lipids
Symptoms: discharge, painful urination, sore throat
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Neisseria gonorrhea
How they cause disease: gonococci attach to mucosal cells lining the genital tract during sexual contact
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Immune response: IgG, IgA, Th cells, CTLs
Immune evasion: pili antigens undergo antigenic variation, so there are several genes for the pili but one is expressed at a time
Symptoms: discharge, painful urination, sore throat
Intestinal
Salmonella
How they cause disease: invades epithelial cells in intestine to cause diarrhea through ingestion of contaminated food/water. Produces toxins that exacerbate symptoms.
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Immune response: IgA, Th cells, CTLs
Immune evasion: antigenic variation of surface proteins, induces regulatory T cell response to dampen immune response
Cholera
How they cause disease: produces cholera toxin that induces disease upon ingestion of contaminated food/water. The toxin binds to surface receptors of intestinal epithelial cells, activating excessive secretion of water and electrolytes
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Immune response: IgA, Th cells, CTLs
Immune evasion: production of cholera toxin, can adhere to the intestinal epithelium without invading host cells
Campylobacter
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Immune response: IgA, Th cells, CTLs
Immune evasion: antigenic variation of surface proteins, inhibits phagocytosis
How they cause disease: Invades the intestinal epithelium and induces an inflammatory response through ingestion of contaminated food/water
Symptoms: diarrhea, fever, gastric ulcers
Shigella/E. coli
How they cause disease: invades intestinal epithelial cells and spreads, causing widespread damage and inflammation
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Symptoms: bloody diarrhea, fever, vomiting
Immune response: IgA, Th cells, CTLs
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Parasites
Protozoa
Giardia lamblia
How they cause disease: causes little disease, highly asymptomatic. Replicates in mucosal tissue.
Symptoms: diarrhea, flatulence, vomiting
Replication location: extracellular, intestines
Immune response: IgA (main, very effective), Th cells, CTLs
Immune evasion: antigenic variation, inhibits phagocytosis, downregulates inflammatory cytokines and upregulates anti-inflammatory cytokines
Zoonosis?: Yes, livestock, beavers, and domesticated animals; vector: house fly
Trypanosoma brucei
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Symptoms: fever, irritability, extreme fatigue, severe headaches
Replication location: extracellular, blood
Immune response: IgG (neutralization, but VSGs evade IgG), ADCC
Immune evasion: VSGs (antigenic variation) change surface structure between different VSG variants, induces suppressor cells following infection
Zoonosis?: Yes, domesticated dogs; vector: tsetse fly
Leishmania
How they cause disease: promastigotes (injected by sandflies) are phagocytosed by host macrophages. They transform into amastigotes, which replicate within cells, and spread, forming lesions (sites of chronic infection)
Symptoms: fever, weight loss, swelling of the spleen and liver
Replication location: liver, intracellular (within macrophages)
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Immune evasion: NO antigenic variation, inhibits activation of macrophages, alters host cell's signaling pathways to avoid apoptosis
Zoonosis?: Yes, dogs and rodents; vector: sandflies
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Helminths
Cestodes (flatworms)
Taenia (tapeworms)
How they cause disease: ingested through contaminated meat and attach to intestinal wall to absorb nutrients and mature. Lays eggs that are shed through feces and contaminate the environment, allowing it to reinfect and form cysts in tissues
Symptoms: diarrhea, flatulence, nausea
Replication location: extracellular, intestine
Immune response: IgE (activates degranulation of mast cells and eosinophils to expel worms - unusual carbohydrates on surface of worms can be recognized as antigens for IgE responses), Th2 cells
Immune evasion: Adult form is too large for phagocytosis, antigen trapping via cyst formation, secretion of protease inhibitors (inhibit cytokine production)
Zoonosis?: Yes, livestock and/or humans
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Nematodes (roundworms)
Ascaris lumbricoides
How they cause disease: ingested through contaminated food and water, obstruction of intestine, nutritional depletion due to competition with host for nutrients, tissue damage
Replication location: extracellular, small intestine
Symptoms: nausea, diarrhea, abdominal pain
Immune response: Th2 cells --> IgG and IgE, activate eosinophils
Immune evasion: antigenic variation; suppress immune cell activation, cytokine production, and antigen presentation
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Ancylostoma (hookworms)
How they cause disease: transmitted through contact with contaminated soil, ingest RBCs for nutrition, causes blood loss and iron deficiency, nutritional deficiencies, tissue damage
Replication location: extracellular, intestine
Symptoms: itching, rash, diarrhea
Immune response: Th2 cells stimulate B cells to produce antibodies (IgE) which causes effector functions such as ADCC and C'
Immune evasion: suppression of immune cell activation and cytokine production, downregulation of host immune responses
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Trichinella
How they cause disease: ingested through contaminated meat, penetrate intestine to migrate through bloodstream, form cysts in muscle tissue. Pathogenesis is due to migration, encystment, and inflammatory response
Replication location: intracellular, intestine
Symptoms: muscle pain, weakness, fever, facial swelling
Immune response: Th1, Th2, IgG, IgE
Immune evasion: suppress immune cell function, induce regulatory T cells and cytokines which dampen effector responses against parasite
Zoonosis?: Yes, reservoirs in domestic pigs, rodents, horses, bears, wolves)
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