Week 8 + 9 Flashcards
(79 cards)
1
Q
What is a vaccine?
A
- a suspension of antigens that is administered to induce immunity
- currently majority of vaccines derive from microbial pathogens for controlling infectious diseases
2
Q
What does a vaccine contain?
A
- antigens
- preservatives + stabilizers - preserving Ag
- specific antibiotics - inhibiting bacterial and fungal growth
- adjuvant - enhancing the immune response to Ag
3
Q
What is the purpose of adjuvant in vaccines?
A
- delay release of antigen from the site of injection
- induce secretion of chemokines by leukocytes
- ex: aluminum hydroxide, saponin, etc.
4
Q
What are the different types of adjuvants?
A
5
Q
What are features of an ideal vaccine?
A
- inexpensive
- consistent in formation, minimal variation
- stable
- proper type of immune response
- range of immunological epitopes
- long-lived immunity
- immunological memory
- no adverse effects
6
Q
What are the kinds of infectious vaccines?
A
- live attenuated
- recombinant organism
- marker
7
Q
What are features of live attenuated vaccines?
A
- intact, viable organism
- low-level infection
- no clinical disease/pathology
- pros:
- rapid immunity
- single dose
- cons:
- can become virulent
- less stable in storage
8
Q
What are features of recombinant organism vaccines?
A
- use carrier organisms
- cannot become virulent
- adjuvant not required
9
Q
What are features of marker vaccines?
A
- differentiate between infected + vaccinated immune response/animals
- ex: IBR w/ deletion
10
Q
What are the types of non-infectious vaccines?
A
- killed whole organism
- subunit
- naked dna
- mRNA
11
Q
What are features of killed whole organism vaccines?
A
- antigenically intact
- unable to replicate or induce disease
- in chemical killing-formalin, alcohol, or alkylating agents
- pros:
- safe
- stable
- no interference w/ other vaccines
- cons:
- slow immunity
- boosters
- less protection
12
Q
What are features of subunit vaccines?
A
- contain immunological proteins/metabolites from a organism
- ex: purified proteins, synthetic peptides,recombinant proteins
13
Q
What are features of naked DNA vaccines?
A
- gene is cloned from plasmid
- plasmids transfer the APC’s; pathogen gene is expressed and processed in APC for antigen presentation
14
Q
What are features of mRNA vaccines?
A
- mRNA of gene of pathogen
- mRNA is expressed and processed by APC for antigen presentation
- ex: covid-19 vaccine (spike protein)
15
Q
What are the kinds of immunization?
A
- active + passive
- immunization: aka vaccination, artificial induction of immunity to protect from infectious diseases
16
Q
What are features of passive immunization?
A
- performed (changed) antibodies administered
- particular antigen
- inhibit endogenous antibody response
- sensitize recipient for hypersensitive reaction
- immediate protection
- fast, TEMPORARY, no memory
- ex:
- artificial: tetanus antitoxin, antivenoms, mAb to SARS-CoV-2
- natural: colostrum
17
Q
What are features of active immunization?
A
- antigen administered
- induced immune response (humoral/cell-mediated)
- memory
- protection proportional to infection severity (no infection to no protection)
- ex:
- artificial: vaccine
- natural: antibody from infection
18
Q
What are methods of vaccine delivery?
A
- injection
- intranasal
- needle-free
19
Q
What are examples of adverse effects to vaccines?
A
- type i hypersensitivity: facial or periorbital edema, pruritus
- FISS (feline injection site sarcoma): surgical removal challenging, poor prognosis
20
Q
Why are diagnostic tests important?
A
- confirm diagnosis
- determine treatment
- epidemiological surveillance
- prevention, control, and eradication strategies
- identification of new pathogens
21
Q
What are the phases of diagnostic testing?
A
- pre-analytical: test selection, sampling, storage, transportation
- analytical: handling and analysis of specimen
- post-analytical: results and interpretation
22
Q
What is used to determine test selection?
A
- pathogen type
- sample type
- test characteristics
- disease phase
- availability
- cost
23
Q
What is the difference between sensitivity and selectivity in test selection?
A
- sensitivity: capacity of a test to correctly identify positive individuals (true positives)
- specificity: capacity of a test to correctly identify the negative individuals (true negatives)
24
Q
T/F: more selective tests can be used to confirm a diagnosis
A
- false; specific
25
What are the test predictive values?
- positive predictive value: probability of a positive test being a TP
- negative predictive value: probability of a negative test being a TN
- prevalence is very important for predictive values
26
What are different immunodiagnostic techniques?
- serology: direct, indirect, titers
- enzyme linked immunosorbant assay (ELISA): direct, indirect, sandwich
- flow assays: lateral, bidirectional
- agglutination
- immunoprecipitation assays: solution based, gel based
- immunofluorescence
- immunohstochemistry
27
What are features of serology?
- in-vitro study of antigen-antibody interactions
- most commonly used diagnostic tool
- basis of several techniques
- usuall used with serum samples
- test infectious diseases, hormones, cancer, autoimmunity
28
What are the 3 main kinds of serology?
- direct: detects presence of ANTIGEN in sample, positive result = INFECTION
- indirect: detects presence of ANTIBODIES in sample, positive result = EXPOSURE
- titers: express concentration of antibodies/antigens, correlates with highest dilution at which they are still detectable via serial dilutions.
29
30
What are features of elisa?
- enzyme-linked immunosorbant assay
- uses enzyme labeled antibodies or antigens, with addition of a substrate, to detect and measure the concentration of analyte
- direct (+ sandwich) and indirect techniques
31
What ELISA technique is this?
- direct
32
What ELISA technique is this?
- indirect
33
What ELISA technique is this?
- direct, sandwich
34
What are features of flow assays?
- lateral or bidirectional
- ELISA-based
- qualitative or semi-quantitative
- point-of-care testing
- fast results
- no lab
35
What are features of agglutination?
- reaction between:
- antibody + particulate antigen
- antibody + soluble antigen coated latex beads
36
What are features of immunopreciptation assays?
- precipitation of antigen-antibody complexes
- exploits the concentrations of antibody and antigen (zone of equivalence) to measure relative quantities (titers)
- 2 methods:
- solution based
- gel based
37
What kind of immunoprecipitation is this?
- solution based
38
What kind of immunoprecipitation is this?
- line of precipitation on the gel indicates the zone of equivalence
39
What are features of immunofluorescence?
- fluorescent-labeled antibodies: tissue or cells, on slides
- requires a fluorescent microscope
- 2 methods: direct + indirect
40
What are features of immunohistochemistry?
- used on frozen or formalin-fixed tissues
- in situ results
- can detect tissue proteins or pathogen antigens
41
What are diagnostic techniques?
- direct examination
- culture
- immunologic methods
- molecular analysis
42
What are kinds of molecular diagnosis?
- electrophoresis
- restriction fragment length polymorphism (RFLP)
- hybridization
- nuclear acid amplification - target
- protein detection
43
What are features of electrophoresis?
- separated in a electrophoretic field
- negatively charged particles —> positive end
- size: smaller is faster
- structure: supercoiled (fastest) > linear > nicked circles (DNA)
44
What are features of restriction fragment length polymorphism (RFLP?)
- analyzing differences among homologous DNA sequences by restriction enzymes
- restriction enzymes: cut DNA at the specific recognition nucleotide sequences (SPECIFIC sequence)
- EcoRI: sticky end
- SmaI - blunt end
- use in paternity tests, forensics
45
What are features of hybridization? Of probes?
- denatured, single-stranded DNA, ssDNA, (probe) binds to a complementary single-stranded sequences
- ex: dot, in situ, Southern, Northern, microarray
- fragment of nucleic acids
- labeled via radioisotope,enzyme, or chemiluminescence
- detect complementary sequences in samples
- high specificity
- variable size
46
What are features of nucleic acid ampification?
- target amplification: enzyme mediated process to synthesize copies of targeted nucleic acid
- polymerase chain reaction (PCR): sensitive!
- isothermal amplification (ex: LAMP)
- true/q PCR
47
What are PCR primers?
- single stranded DNA fragments complementary to sequences flanking the region to be amplified
- distance between primer and binding sites determines size of PCR product
- determine specificity
48
What are features of primers?
- types: random or specific
- primers: product size, annealing temperature, specificity
- nucleotide composition
49
What are PCR variations?
- reverse-transcriptase PCR
- nested PCR
- multiplex PCR
- quantitative or real-time PCR
- etc.
50
What are features of real-time or quantitative PCR?
- probe or dye to generate a fluorescent signal from the product
- signal in real time allows quantification of starting material
- signal: exponential curve with lag phase, log phase, and stationary phase
- lag phase: inversely proportional to amount of starting material
51
What are features of isothermal activation/LAMP?
- pros:
- no thermal cycles needed, but need room temp
- quick - 1H
- sensitivity > PCR
- visible results
- cons: complicated design of primer plates
52
What are phenotypic characteristics (observable characteristics) of microorganisms?
- morphology: size, shape, structure
- biochemical reactions: staining, cell inclusions
53
What are advantages and disadvantages to microscopic identification?
54
What are features of concentration techniques?
- work to increase concentration of pathogens in the sample
- common in parasite diagnosis
- ex:
- flotation techniques
- sedimentation techniques
- baermann test for larval identification
55
What are features of fecal flotation?
- gross examination
- fresh feces: detect parasites in GI tract, liver, bile ducts
- fecal flotation: based on differences in specific gravity between the parasites eggs, larvae, cysts, or oocysts, and the majority of fecal debris
- determine presence of parasite, egg types, general level of infection (eggs per field view)
- McMaster egg counting slide
56
What are features of the baermann technique?
- method for extraction of nematode larva from fresh feces (ex: lung worm larvae in feces, larvae from fecal cultures, pastures,soil,tissues, etc.)
- warm water stimulates live larvae in the sample to move out and gravity pulls them to the bottom of the container
57
What are the two main categories of staining techniques?
- simple stain (only 1 dye)
- identification of morphology and cellular arrangement
- drawback: may not stain all components, difficult interpretation
- differential stain (more than 1 dye)
- identification of morphology and cellular arrangement
- distinguish between different cell types + structures
- drawback: multistep method requires more time, reagents, expertise
58
What are features of hematoxylin and eosin stain (H&E)?
- common tissue stain used to identify a range of normal/abnormal cells + tissues, can reveal viral, bacterial, fungal, and parasitic infections
- different structures have different dye affinities
- hematoxylin (basic stain): stains acidic (basophilic) or - charged particles (ex: nuclei, chromatin) PURPLE
- eosin (acidic stain): stains basic (acidophilic) or + charged components (ex: cytoplasmic components + granules) and extracellular components (ex: muscle, RBC) PINK
- detection of VIRAL INCLUSION BODIES: aggregates made mostly of proteins, represent site of viral replication
- virus cause virus-specific changes in cell structure, organization, and morphology
59
What are features of Diff-Quick?
- commercial romanowsky stain
- used in histological rapid staining
- fixative (fast green in methanol) > stain solution 1 (eosin G) > stain solution 2 (methylene blue)
- air dried sample prior
- modified wright-gives a stain: differential stain for adherence of pathogenic bacteria to cells (ex:blood cells, stain chromosomes)
60
What are features of Gram-stain?
- distinguish betweeen Gram + and Gram - bacteria based on CELL WALLS (peptidoglycan)
- G+ : PURPLE
- G - : PINK
61
What are some stains for specific bacterial structures?
- acid fast stain: stains organisms with impenetrable cell wall (ex: mycobacterium, cryptosporidium)
- capsule stain: negative sting technique; contrast a translucent, darker colored background with stained cells but unstained capsule (ex: bacillus anthracis, klebsiella pneumoniae, clostridium sp.)
- endospore stain: spores are dyed by heating malachite green dye
- flagella stain: flagella are thickened with mordant
62
What are some fungal and parasite stains?
- lactophenol cotton blue stain: stain chitin in cell wall of fungi
- gomeri methenamine silver (GMS): dark brown staining of fungal cell wall, surrounding tissue green
- periodic acid schiff (PAS): mucin stain
- Wheatley’s trichrome stain: detection of Protozoa
63
What do cultures allow observation of? How?
- mostly bacteria + fungi
- viruses = cell cultures
- different environmental and nutritional requirements
- ensure pathogen growth of desired specimen
- enrich number of pathogens for more study
- determine pathogen identity
64
What are pros and cons of culturing?
- pros:
- identification
- assessment of AMR
- ability of microbe to cause disease
- study characteristic and genetics
- cons:
- time consuming (2-10 days)
- expensive
- un-culturable bacteria, no ID
65
What are fastidious bacteria?
- bacteria that require specific nutrients and culture conditions
66
What are some kinds of fastidious bacteria?
- aerobes, anaerobes, temperature dependency
67
What is the great-plate culture anomaly?
- ~1% of bacteria is culturally
- unculturable: used to describe bacteria not grown on artificial media to date (not enough info)
68
What are kinds of culture media?
- agar (solid)
- nutrient media: general growth
- selective media: growth of suspected agent
- differential media: most are selective and aid in ID
- broth (liquid)
- nutrient broth
- enrichment broth: increase number of specific bacteria and limit others
69
What are features of agar plate growth?
- bacteria grow as colonies
- bacterial colony: visible mass of bacteria originating from a single mother cell aka clones
- streak plate method to obtain pure cultures
- oxygen requirements
70
What are kinds of non-selective nutrient media?
- basic nutrient media
- trypticase soy agar (TSA)
- luria bertani (LB) agar
- mueller-hinton (MH) agar
- enriched nutrient media
- blood agar
- brain heart infusion (BHI) sugar
- chocolate agar
- lysed-blood agar
71
What are kinds of selective nutrient media?
- selective for gram-positive organisms
- phenylethyl alcohol agar (PEA)
- selective for fungi
- sabouraud dextrose agar (SDA)
- selective for gram-negative organisms
- eosin methylene blue agar (EMB)
72
What will occur if you add antibiotics to agar?
- only antibiotic resistant bacteria will grow
73
What are kinds of differential media?
- blood agar
- hemolysis
- MacConkey agar
- selective for G-
- lactose fermentation (pink colonies)
- mannitol salt agar
- G+
- mannitol fermentation (yellow colonies)
- CLED agar: urine bacteriology
- cysteine-lactose-electrolyte deficient
- supports growth of common urinary pathogens (ex: proteus, klebsiella)
- lactose fermentation
74
What are biochemical tests for bacterial identification?
- based on metabolic characteristics
- enzyme production
- catalase: breaks down H2O2
- coagulase: causes fibrin in blood to clot
- urease: hydrolysis urea
- tryptophanase: ability to convert tryptophane to indole
- carbon source utilization
- carbohydrate fermentation: lactose, sucrose, glucose, xylose
75
What are features of UTI culture paddles?
- semi-quantitative culture count
- presumptive ID of common uropathogens
- EMB agar: selective for gram - bacteria
- CLED agar: non-selective
- interpretation of results
- colony density: degree of infection
- growth on EMB: gram -
- color on CLED: lactose fermentation
76
What are features of Flexicult Vet urinary test?
- semi-quantitative colony count
- presumptive ID of uropathogens
- antibiotic susceptibility information
- test within 30 mins of mid-stream urine collection, incubate at 37 C for 18-24 hours
- >10^3 pathogen/mL = infection
- no growth = antibiotic susceptible
77
What is the cycle of diagnostic process?
78
What are differences between on-site analysis and diagnostic lab?
79
What are features of a good diagnostic lab?
