MMI 302-3 Review

  1. Mutualism
    Both Organisms benefit
  2. Commensal
    Benefits one, neutral to second
  3. Parasitism
    Benefits one, harms second
  4. Parasite
    An organism that grows, feeds, and is sheltered on or in a host organism to the detriment of the host
  5. Endo Human Parasite
    Infects inside body, Protozoan, Helminths
  6. Ecto Human Parasite
    Infestation on or in skin, Ticks, ect
  7. Defenitive Host
    host for the parasite when it is in the sexual stage of life) -e.g. Humans with Schistosoma, Mosquitoes with malaria
  8. Intermediate Host
    host for the parasite when it is developing or reproducing asexually) -e.g. Snails with Schistosoma, Humans with malaria
  9. Incidental/Accidental Host
    host is not an obligate part of parasite life -e.g. Humans with Toxoplasma
  10. Reservoir Host
    host that carry parasite in wild -e.g. Mice with Toxoplasma
  11. Vector Host
    host species that transmit an infectious form of parasite to another host -e.g. Mosquitoes with malaria, Snails with Schistosoma
  12. Aspects of Epidemiology
    • Geographic Distribution (total area regardless of intensity)
    • Prevalence (Sporatic, Endemic, Epidemic)
    • Incidence (New infections in polulation/unit time)
  13. Kingdoms/Phylums of Human Parasites
    Protista and Anamalia
  14. Trypanosoma Life Cycle
    • -Infected bug takes blood meal, transmits metacyclic Trypanosoma through feces (infective stage)
    • -Metacyclic trypomastigote penetrates various cells at bite point
    • -Transform into amastigotes within cells -Amastigotes multiply by binary fission in infected tissues
    • -Amastigotes transform into trypomastigotes -Trypomastigotes burst out of cell into bloodstream (diagnostic stage)
    • -Some trypomastigotes invade other cells and become amastigotes
    • -Bug takes a blood meal, uptakes the trypomastigotes
    • -Epimastigote phase develops in midgut -Epimastigotes multiply in midgut
    • -Metacyclic trypomastigotes in hindgut
    • -Repeat
  15. Diagnosing Trypanosoma
    Look for trypanosoma in blood, test strips
  16. Entameoba histolytica Lifecycle
    • Mature cyst ingested
    • -Excystation occurs, becomes Trophozoite -Trophozoite multiplies
    • -Some trophozoites become cysts, mature
    • -Mature cyst excreted in feces
  17. Diagnosing Entameoba histolytica
    Find cysts in bloody diarrhea, stool antigen/PCR, trophozoites contain RBCs
  18. Fasciola hepatica Life Cycle
    • -Unembroynated eggs passed in feces -Embryonated eggs in water
    • -Miracidia hatch, penetrate snail shell
    • -Inside snail sporocysts turn to rediae turn into cercariae
    • -Free-swimming cercariae encyst on water plants -Metacercariae consumed by humans, sheep, or cattle
    • -Encyst in duodenum
    • -Adults in hepatic binary ducts
    • -Repeat
  19. Echinococcus granulosus morphology
    • Adult: Long, sectioned worm, two eyespots, entirety of reproductive tract in bottom half
    • Hydatid Cyst: Large outer membrane, brood capsules, hydatid sand, inner daughter cysts
  20. Tapeworm Types
    Solium (Pork) and Saginata (Beef)
  21. Tapeworm Life Cycle
    • -Egg/Graved proglottids released in feces, passed into environment
    • -Pig/Cattle consume egg/graved proglottids -Oncospheres hatch, penetrate intestinal wall -Circulate to musculature
    • -Develop into cysticerci
    • -Human ingests infected muscle tissue
  22. Schistosome Geography
    East coast of South America, Central and East Africa, Assorted areas in South East Asia
  23. Malaria Organisms
    P. falciparum, P. vivax, P. knowlesi, P. ovale, P. malariae
  24. Locaitons of Malaria in body
    Hepatocytes and Erythrocytes
  25. Definitive Host of Malaria
  26. Intermediate Host of Malaria
    Humans (Primates for P. knowlesi, slowly beoming humans)
  27. Transmission Vector of Malaria
    Anopheles female misquitos, congenital/needle transfer
  28. Epidemiology of Malaria
    • -200 mil cases, 655k deaths
    • -Most fatalities in children and primigravida women -Increased drug and insecticide resistence
    • -P. falciparum most dangerous
    • -Slowly being controlled
    • -40% of human population live in endemic regions
  29. Causes of Malarial Death
    Death from multiple organ failure, cerebral malaria, chronic anemia, ARDS and placental malaria
  30. Malarial Life Cycle
    • -Female mosquito carrying parasite feeds on human and introduces sporozoites to bloodstream -Sporozoites invade liver cells
    • -Over 5-16 days, sporozoites grow and divide, produce many haploid merozoites (May stay dormant at this stage)
    • -Merozoites re-enter bloodstream, invade red blood cells
    • -Merozoites reproduce asexually, infected cell proliferate
    • -Mosquito bites human, imbibes merozoite infected RBCs
    • -Infected RBCs burst, releasing gametocytes -Gametocytes develop into gametes
    • -Male and female gametes fuse into diploid zygotes -Develop into actively moving ookinetes
    • -Ookinetes burrow into misquito midgut wall, form oocysts
    • -Oocysts divide and develop over 8-15 days, creating many sporozoites
    • -Oocysts burst, release sporozoites that travel to salivary glands and cycle continues
  31. Malarial Incubation Period
    7-30 Days
  32. Uncomplicated Malaria
    -Adults: Fever/cold stage, hot stage, sweating stage, 6-10 hours flu like symptoms, anemia, hepato-splenomegly.Children: Fever/Diarrhea/Vomiting
  33. Severe Malaria
    Cerebral Malaria, Respiratory Distress Syndrome, Anemia
  34. Cerebral Malaria
    • -Unarousable coma, not attributable to any other cause
    • -P. falciparum present
    • -1% of P. falciparum cases result in cerebral and 10-20% of these die
    • -Usually seen in children over 2 years
    • -Mechanical Hypothesis: Cytoadhesion of infected erythrocytes
    • -Inflammation hypothesis: Malarial toxin and excessive cytokines
  35. Respiratory Distress Syndrome
    • -Seen in African children and Asian adults
    • -Caused by injury to lung micro-vascular endothelium/aveolar epithelium via excessive inflammation
    • -Also by heart failure, parasite sequestration, or increased respiration
    • -Associated with metabolic acidosis, usually involving lactic acid
  36. Anemia
    • -Caused by falciparum or vivax
    • -Destruction of parasitized RBC by developing parasites
    • -Reduces ability to transport oxygen
    • -Increased rate of removal for un-infected cells -Suppressed erythropoiesis
    • -Immune destruction of RBCS with parasite antigens -Usually occurs <2 years
  37. Pathology (Merozoite Bursts)
    • -P. vivax/P.ovale: 48 hr spike merozoite burst
    • -P. malariae: 72 hr spike merozoite burst
    • -P. falciparum: 48 hr broad merozoite burst
  38. Malarial Invasion of RBCs
    • -Engage binding receptors on RBC surface
    • -Undergo apical reorientation
    • -Develop Junction formation
    • -Signal to release organelle contents
    • -Initiate actin-myosin moving junction, brings parasite into RBC
    • -Parasite develops in RBCs lacking expression of MHC molecule
  39. Malarial Variant Surface Antigens
    • -Express parasite antigens on RBC surface: PfEMP1
    • -Mediates binding to host tissue/stopping spleen from clearing parasites
  40. Malarial Blood Behavior
    • -Blood can exhibit:
    • -Rosetting (Clumps of regular blood surrounding infected cell)
    • -Endothelial cytoadherence
    • -Rolling on endothelium
    • -Vascular occlusion

    • Malarial Diagnostic Tests (Microscopic)
    • -Geimsa stain of thin/thick smears
    • -Each strain look slightly different
    • -P. falciparum: multiple rings of RBC, no trophozoites/schizonts
  41. Malarial Diagnostic Tests (Non-microscopic)
    • -Rapid dipstick immunoassay
    • -PCR
  42. Malarial Immunity
    • -Slow to develop, multiple infections needed
    • -Short lived
  43. Malarial Treatment
    • -Chloroquine, mefloquine, quinine
    • -Multidrug resistant common (esp. chloroquine) -Newer drugs: maladrone, doxycycline, clindamycin and artesunates
    • -IV quinidine still used for cerebral-Ovale/vivax require primaquine
    • -Patients traveling abroad: prophylactic w/ chloroquine, fansidar, malarone or doxycycline
  44. Malarial Prevention
    • -Avoid mosquitos: repellents and bednets
    • -New vaccine: RTS, circumsporozoite
  45. Causes for Malarial Resurgence
    • -Insecticides and anti-malarials after WWII gave hope
    • -Resistance quickly developed
    • -Little research into new drugs-Fake drugs-Single use therapy, need combination therapy to stop resistence
  46. Malarial Control Measures
    Antimalarials, Vaccines and Vector Control (Bed-nets, mosquito pathogens/sterility/mutants)
  47. Natural Barriers
    Skin, mucus, cilliated epithelium, gastric acid/bile, normal microbiota
  48. Innate Immunity
    -Pathogen-associated molecular patterns (PAMPs), antigen-nonspecific (i.e. fever, complement, iron-binding proteins, antimicrobial peptides, phagocytes)
  49. Adaptive Immunity
    -Memory responses (antigen-specific), T-cells, ect.
  50. Mechanisms of Host Immune Evasion
    • -Capsules
    • -Antigenic variation
    • -Anti-immunoglobulin proteases
    • -Disruption of complement cascade
    • -Inhibition of opsonic action
    • -Inhibition of phagocyte chemotaxis
    • -Destruction of phagocytes by leucotoxins
    • -Intracellular replication
  51. Bacterial Virulence Factors
    • -Adhesions
    • -Cell invasion
    • -Exotoxins
    • -Superantigens
    • -Capsules
    • -Evasion of immune defenses:complement resistance, IgA proteases, cellular invasion, and antigenic variation-Iron acquisition (siderophores)
    • -Disruption of host signaling mechanisms (modulins)
    • -Motility
  52. Uropathogenic E. coli colonization pattern
  53. Uropathogenic E. coli virulence factors
    • -Fimbriae-Phase switch between Type 1 and P Type
    • -Iron acquisition systems-Toxins: Hemolysin/CNF-1/Sat
  54. P fimbriae bind to
  55. Type 1 bind to
    alpha-methyl-D-mannosides on glycoproteins
  56. Yeast Cell Walls
  57. Yeast Agglutination Assay
    Looks grainy versus cloudy when posistive
  58. Expression of fimS
    Binding of promoter sets Type 1
  59. FimBE-like Recombinase Loci in CFT073
    fim, ipu, and ipb genes
  60. Falkow's Postulates
    • -Phenotype should be associated with pathogenic strains
    • -Knockout gene should remove virulence factor -Replacement/removal of knockout should return virulence
  61. Negative Selection
    • -Mater Plate
    • -Growth on complete medium
    • Press Master Plate into sterile velveteen affixed to wooden block with a plastic hoop
    • -Velveteen is imprinted with all the colonies
    • -Press velveteen block into complete and minimal medium
    • -All colonies should grow on complete pressed medium, mutants do not grow on minimal
    • :Assume mutants lack ability to produce something not on minimal plate
  62. Positive Selection
    • Brute Force Vrs. Semi-Brute Force Approaches to Look for Attenuated Mutants
    • -Method A: 10,000 random transposon mutants are individually used to infect animals/tissues
    • -Method B: Pools of 96 independent mutants used to interrogate virulence
    • -Still need 100-120 animals to acquire sufficient coverage for genome the size of E. coli
  63. Plasmodium Staining
    • -Smear blood drop across slide thinly
    • -Fix red blood cells to slide with methanol (submerge for 1 minute)
    • -Drain from slide, let slide air dry-Emerge in giemsa stain, incubate for 5 min at room temp-Pour off stain, briefly wash with water-Count slide
  64. UP E. coli resistent to:
  65. LacZ positive mutants
    Take up red color from BAP, are indicative of active fimS
  66. Pathogenicity Island
    • -Help distinguish pathogenic from non-pathogenic strains of closely related bacteria
    • -Chromosomal clusters of pathogenic-specific virulence genes
    • -Found inserted at tRNA loci
    • -Trait common to some lysogenic phage
    • -Can be excised at high frequencies in some cases being lost, resulting in deletion
    • -Question of origin and mobility to other bacteria
  67. Complement Based bacterial lysis
    • -C5b bind C6/C7
    • -C5b67 complexes bind to membrane via C7
    • -C8 binds to complex and inserts into cell membrane
    • -C9 molecules bind to complex/polymerize
    • -1-16 C9 molecules bind to form pore in membrane
    • -Create membrane lesions
  68. Metal Iron Transport
    • -Iron is growth limiting
    • -Host produces lactoferrin and transferrin to chelate free iron
    • -Inflammation raises these
    • -Siderophores
    • -Inhibition of pathogenic growth depends on reducing iron
  69. Ferric-siderophore receptor
    • -Receptor in outer membrane-TonB/ExbB/ExbD complex links to CM through periplasm
    • -Ferric-siderophore binds PBP
    • -ICM/ABP use ATP to pump ferric-siderophores into cell
  70. Virulence: Adherence
    • -Pili/fimbriae
    • -to host or other bacteria
    • -Non-fimbrial surface proteins
    • -Capsule
    • -Lipoteichoic acid
    • -Flagella
    • -Receptor
    • -Ligand interaction:Cells,Viruses,Antibodies,Lectin,Hormones,Enzymes,Bacterias
  71. FimS flip Occurrence
    1 in 1,000/10,000
  72. Gene Responsible for hemolytics in UP E. coli
    UPEC-536, mutants have less beta-hemolysis
  73. Assay for siderophore
    Chrome Azurol S medium (CAS), are blue when iron is bound to pigment, when siderophores take the iron it turns orange
  74. Yeast Agglutination inhibited by
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MMI 302-3 Review
Exam 3