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SEROLOGY 101

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SEROLOGY 101 Or How To Interpret Those Funny-Looking Graphs Dr. Victoria Bowes Animal Health Centre Abbotsford, BC Presented June 4, 2003 Avian Immune System NON ... – PowerPoint PPT presentation

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Title: SEROLOGY 101


1
SEROLOGY 101
  • Or How To Interpret Those Funny-Looking
  • Graphs
  • Dr. Victoria Bowes
  • Animal Health Centre
  • Abbotsford, BC
  • Presented June 4, 2003

2
Avian Immune System
  • NON-SPECIFIC and SPECIFIC
  • border defenses (innate)
  • surveillance (white blood cells)
  • rapid elimination of harmful substances

3
Avian Immune System
  • NON-SPECIFIC IMMUNITY
  • anatomic skin, mucus, cilia
  • body temperature
  • genetic factors
  • sneeze, cough, vomit
  • age, nutrition

4
Avian Immune System
  • SPECIFIC IMMUNITY
  • Passive (provided in the yolk to chicks)
  • Acquired (must be produced by the bird)
  • (by infection or vaccination)
  • Cells lymphocytes, macrophages
  • Antibodies - produced by B-lymphocytes
  • Memory

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6
The Immune Response
  • Must recognize foreign or potentially harmful
    intruders
  • Produce and co-ordinate specific (antibodies) and
    non-specific (lymphocytes) reactions to ATTACH,
    TRAP and
  • ELIMINATE

7
The Immune Response
  • antibody a protein produced in response to the
    presence of a specific antigen
  • antigen a molecule capable of eliciting an
    immune response, usually large, complex and
    foreign

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10
The Immune Response
  • Example
  • An IB virus that has its surface receptors
    coated in antibodies cannot attach itself to the
    cells lining the trachea, the first step in
    infection.

11
The Immune Response
  • PRIMARY novel foreign antigen is processed,
    specific antibodies are slowly produced
    (short-lived) and memory cells become dormant
  • SECONDARY memory cells encounter their
    specific antigen and are activated, antibody
    production is rapid and potent

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13
Vaccines
  • Vaccines INSURANCE (something you may never use
    but you be very glad to have if ever needed)
  • Live gives best immune response but has side
    effects (weakened strains of virus)
  • Killed less side effects but poorer immune
    response (excluding adjuvants)

14
Serology
  • The detection of antibodies in serum
  • Test methods plate agglutination
  • hemagglutination
    inhibition
  • ELISA
  • Interpreting results negative
  • vaccination
  • field
    challenge

15
Blood
  • 55 fluid mostly water
  • 45 solid cells (5001 red white cells),
    enzymes, proteins, nutrients
  • transports oxygen nutrients while removing
    waste
  • serum Vs plasma

16
Blood Serum
17
The Animal Health Monitoring Lab
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19
ELISA
  • E nzyme
  • L inked
  • I mmuno
  • S orbant
  • A ssay

20
ELISA
  • easily automated
  • sensitive specific
  • antigen-coated test plates capture specific
    antibodies in diluted blood sample and reagents
    turn shades of blue depending and the amount of
    antibody present
  • generates computer graph histogram

21
The Elisa Plate Reader
22
ELISA plate
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24
HI plate
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26
Serological Strategies
  • DIAGNOSTIC field challenge
  • paired samples
  • ASSESS VACCINATION RESPONSE protective and
    maternal titres

27
Serological Strategies
  • small sample size is used to infer the condition
    of a larger population of birds
  • statistical techniques dictate sample size of
    significance
  • variables flock size 12-24 /air space?
  • testing type
  • pooling samples reduces test sensitivity
    (dilutional)

28
Interpretation
  • Serology results must be interpreted in
    association with other sources of information
    vaccination history
  • production data
  • condemnation data
  • clinical signs
  • necropsy findings

29
Limitations
  • seroconversion takes 4-20 days
  • tests only circulating antibody
  • static measure (rising, stable, falling)
  • cant differentiate field vs. vaccine strains
  • cross-reactions
  • test error

30
Titres or Titers
  • a unit of measurement of antibody
  • uses pre-determined reference numbers
  • historically measured by sample dilution until a
    standard reaction was produced
  • dilution titre
  • a titre of 32 ½ the antibody of 64
  • 2X the antibody of
    16

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34
Interpreting Results
  • 123 A BB 18 X 345 IBD-XR
  • 123 flock
  • A or B 1st or 2nd bleeding
  • BB broiler breeder (or TU, BR)
  • 18 age in weeks
  • X submitter code (hatchery, vet)
  • 345 owner code
  • IBD-XR test name

35
Interpreting Results
  • MEAN TITRES
  • the average titre number (zero to gt10,000)
  • each titre group (bottom line of graph)
    represents a different titre range depending on
    the virus

36
Titre Group Reovirus MG/MS IB, IBD NDV AE
0 0-537 0-395 0-444
1 538-1075 396-999 445-769
2 1076-1999 1000-1999 770-1215
3 2000-2999 2000-2999 1216-1661
4 3000-3999 3000-3999 1662-2107
5 4000-4999 4000-4999 2108-2553
6 5000-5999 5000-5999 2554-2999
7 6000-7999 6000-7999 3000-3444
37
Interpreting Results
  • UNIFORMITY
  • CV (coefficient of variation)
  • lt 30 excellent
  • 30-50 good
  • 51-80 fair
  • gt 81 poor or bimodal

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39
Standards
  • Optimum Titres minimum titre level to provide
    long duration immunity for breeder hens, also
    assuming protective. Assessed 4 weeks post-killed
    vaccine.
  • ND 8/10 gt 7 IBV 8/10 gt 6
  • IBD 8/10 gt 8 Reo 8/10 gt5
  • AE 8/10 gt4

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Interpretation
  • EXAMPLES
  • The following are typical histograms

42
5 week unvaccinated broilersnegative titres
43
5 week broilersIBD vaccination or challenge?
44
5 week vaccinated broilersIBD challenge, poor
vaccine?
45
62 week layer bloods waning titres
46
pre post-killed IBD titres
47
pre post-killed reovirus titres challenge?
48
NDV titres poor prime boosted by killed vaccine
49
IBVuneven prime, suboptimal titres
50
Reovirus titrespossible vaccine field
challenge?
51
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