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2012-10-18 19:31:45
Lab Tech ll

Lab Tech ll
Show Answers:

  1. How big are viruses?
    • submicroscopic particles
    • 20 - 150 nm (1 one thousandth of a micron, 1 one millionth of a millimeter)
  2. What kind of microscope do we need to use in order to see a virus?
    electron microscope
  3. What is nm?
  4. What do viruses contain?
    either RNA or DNA
  5. Where do viruses replicate?
    • only in living cells
    • can exist in the environment, but can not replicate in the environment
  6. What are obligate intracellular parasites?
    parasites that can only replicate in living cells and can not replicate in the environment
  7. Define virion.
    a virus particle
  8. Define viremia.
    virus in the blood - spreading from point A to point B
  9. Define incubation period.
    from infection till the animal shows clinical signs
  10. How long is the incubation period for viruses?
    about 3 - 5 days
  11. Viruses grow ____ than bacteria but _____ than fungi.
    • slower
    • faster
  12. Viruses are _____ covered by _____.
    • nucleic acids
    • protein
  13. What are capsomeres?
    individual viral proteins that make up the capsid.
  14. What is the capsid?
    protein covering the nucleic acids
  15. What are the purpose of nonstructural proteins?
    enzymes that allow for take over of hot's biosynthetic apparatus - allows the virus to take over the cell
  16. What are some examples of nonstructural proteins?
    • RNA reverse transcriptase
    • polymerases
    • protein kinases
  17. What is the envelope?
    lipid and glycoprotein covering the virus to increase virulence
  18. Do all viruses have envelopes?
  19. What does virulence mean?
    the destructiveness of the virus
  20. How do viruses get an envelope?
    from the host cell
  21. What are peplomers?
    glycoprotein spikes on the outside of the virus
  22. What is the purpose of peplomers?
    helps the virus attach to the membrane of the cell
  23. Do all viruses have peplomers?
  24. What are the different RNA viruses?
    • Reovirus
    • Rhabdovirus
    • Retrovirus
    • Paramyxovirus
    • Orthomyxovirus
    • Togavirus
    • Coronavirus
    • Calicivirus
    • Arenavirus
    • Picornavirus
    • Bunyavirus
  25. What are some Caliciviruses?
    • Feline calicivirus
    • Vesicular exanthema
  26. What are the clinical signs of the Feline calicivirus?
    • upper respiratory infection
    • lesions in the mouth
  27. What species does Vesicular exanthema (calicivirus) affect?
    • sheep 
    • goats
  28. What are some Picornavirus?
    • Foot and mouth disease
    • Swine vesicular disease
    • SMEDI
    • Rhinovirus in the horse
  29. Foot and mouth disease is an exotic disease.  How did we get it this way?
    test and slaughter
  30. What does an exotic disease mean?
    it is not seen in our country, only in other countries
  31. What does the rhinovirus (picornavirus) in horses cause?
    upper respiratory infection
  32. What is the main Rhabdovirus?
  33. What is rabies?
    neurologic disease seen in all mammals
  34. Which types of animals can not get rabies?
    • reptiles
    • birds
  35. How is rabies spread?
    • spread by bites
    • virus is in the saliva
  36. Which states are number 1 and 2 in having the rabies virus?
    • Texas - #1
    • Virginia - #2
  37. Why is the rabies virus mainly seen in wildlife?
    because we vaccinate our domestic animals
  38. What are some Paramyxoviruses?
    • Canine distemper
    • Canine parainfluenza
    • Bovine parainfluenza 3 (Bovine PI3)
    • Respiratory syncytial virus
    • Rinderpest
  39. Is the Canine distemper (Paramyxovirus) tissue specific and species specific?
    no, can affect different types of tissue in the body and can affect more than just dogs
  40. What does the Canine parainfluenza virus (Paramyxovirus) cause?
    upper respiratory infection
  41. Which Paramyxovirus an exotic disease?
    Rinderpest (seen in Africa)
  42. What are some Coronaviruses?
    • TGE (transmissable gastroenteritis)
    • FIP
    • Canine coronaviral enteritis
    • Feline enteric coronavirus
    • Bovine neonatal diarrhea
  43. What animal does TGE (Coronavirus) affect?
  44. What are some Togaviruses?
    • EEE (eastern equine encephalitis)
    • WEE (western equine encephalitis)
    • VEE (venezuela equien encephalitis)
    • BVD
    • Hog cholera
  45. What does the Togavirus require in order to be spread?
    arthropod vector
  46. Which Togavirus is exotic?
    Hog cholera
  47. Do we see Togaviruses in carnivores?
  48. What are some Reoviruses?
    • Rotavirus enteritis
    • Bluetongue virus
  49. What do Reoviruses cause in most species?
    enteritis and respiratory diseases
  50. What species gets Bluetongue virus (Reovirus)?
  51. Are Reoviruses common?
  52. What are some Retroviruses?
    • Oncornavirus (bovine and feline leukemia)
    • Lentivirus (Caprine Encephalitis Arthritis, Equine Infectious Anemia, FIV, Visna-maedi)
  53. How are Lentiviruses spread (Retrovirus)?
    by direct contact such as biting
  54. What are the DNA viruses?
    • Pox virus
    • Parvovirus
    • Herpesvirus
    • Adenovirus
    • Papovavirus
    • Iridovirus
  55. What are some Pox viruses?
    • Cow pox
    • Orf (sheep) - Contagious ecthyma
    • Horse pox
    • Avian pox
    • Monkey pox
  56. Which Pox virus is the most common?
    Avian pox
  57. What part of the body do Pox viruses usually infect?
  58. Are pox viruses seen in carnivores?
  59. What are some Herpes viruses?
    • Infectious Bovine Rhinotracheitis
    • IPV (pustular vulvovaginitis)
    • Malignant catarrhal fever (hoof stock)
    • Equine rhinopneumonitis
    • Feline rhinotracheitis
    • Canine herpes
    • Marek's disease (chickens)
  60. What is the main clinical sign for herpes viruses?
    mostly respiratory
  61. What are some Parvoviruses?
    • Canine parvovirus
    • Feline panleukopenia
    • Porcine parvovirus
    • Raccoon parvovirus
  62. What are some Adenoviruses?
    • Infectious canine hepatitis
    • Canine adenovirus 2 (kennel cough)
  63. What are the three diseases that cause kennel cough?
    • Canine adenovirus 2
    • Canine parainfluenza
    • Bordetella
  64. What do Adenoviruses usually cause?
    respiratory/GI diseases
  65. What are some Papavoviruses?
    Papillomatosis (warts)
  66. What species is Papillomatosis (Papvovirus) common in?
    cows and dogs
  67. What are some Flaviviruses?
    West Nile virus
  68. What does West Nile virus (Flavivirus) cause?
  69. How is West Nile virus (Flavivirus) transmitted?
    by insects
  70. What are some Circoviruses?
    • Porcine circovirus
    • Psitticine Beak and Feather Disease
  71. What are some Filoviruses?
    Hemorrhagic diseases in primates (Ebola, Marburg, Reston)
  72. What are the steps of how the virus effects the cell?
    • Attachment:  must get to cell and attach to it first
    • Penetration:  penetrates the cell - pinocytosis - brings the cell in
    • Uncoating:  protein coat and envelope go away - now it's a "naked cell"
    • Biosynthesis:  nucleic acid from the virus gets into the nucleic acid from the cell and makes the cell stop doing it normal function and start making more of the virus
    • Maturation and Release:  virus either reassembles  in the cell and destroys the cell or leaves the cell to go to another one and starts the process over again
  73. What are the different types of infection?
    • clinical
    • subclinical
    • persistent
    • latent
    • carrier
    • slow
  74. What are clinical infections?
    shows signs
  75. What are subclinical infections?
    does not show any signs
  76. What are persistent infections?
    lingers in the body
  77. What are latent infections?
    virus is in equilibrium with the immune system - the virus is not doing anything until soemthing suppresses the immune system
  78. What are carrier infections?
    shed the virus even after recovery
  79. What are slow infections?
    long incubation periods
  80. What are the different routes of infection?
    • inhalation
    • ingestion
    • direct contact
    • in utero
  81. What does "horizontal spread" of an infection mean?
    spread from animal to animal
  82. What does "vertical spread" of an infection mean?
    spread from mother to offspring
  83. What are the different types of Host Immune Responses we have to fight off viruses?
    • Interferon
    • Macrophages
    • Immunoglobulins
    • Cell-Mediated Immunity
  84. What is interferon?
    produced mostly by T-lymphocytes that then produce antiviral proteins which stops the penetration of the virus into other cells and protects the other cells
  85. Is interferon immune response specific or non-specific?
    non-specific which means there isn't one for each specific virus...they work for all the viruses
  86. What do macrophages come from?
  87. What do macrophages do?
    • engulf the virus
    • make interleukin - 1 which is a chemical that activates T-lympohocytes to kill cells
    • T lymphocytes kill the macrophages
  88. What are immunoglobulins?
  89. Are immunoglobulins specific or nonspecific?
    specific to each virus
  90. How do immunoglobulins work?
    • there is in increase in immunoglobulins M within 7 days of the first exposure to the viruse
    • B lymphocytes increase in 10 - 14 days after exposure
    • After 2 weeks there is an increase in immunoglobulins G
    • Anamnestic (memory) response with a second exposure
  91. What is a cell mediated immunity?
    • Macrophages process virus for the T cells
    • T cells then become cytotoxic
  92. How are viral diseases often diagnosed?
    clinical signs 
  93. How do we definitively diagnose a viral disease?
    lab testings
  94. What do we need before we do diagnostic testing?  Why? 
    suspicion of what virus it is, tests are very specific - different tests for each virus
  95. What are the two types of tests?
    • antibody tests
    • antigen tests
  96. What are antibody tests?
    tests for antibodies, can only tell us if the animal has been exposed to something and has the antibodies - does not tell us if the animal currently has the active form of the virus
  97. What are antigen tests?
    determines if the virus is active in the animal
  98. What are the general findings of an animal with a virus?
    • characteristic history
    • characteristic signs/lesions
    • changes in CBC
    • biochemical changes (relate to organ system that is affected)
  99. What are some changes we will see on a CBC?
    • panleukopenia
    • lymphopenia
  100. What is histopathology usually done?
    once the animal is dead
  101. What does a DNA virus look like in a histopathology?
    intranuclear (in nucleus)
  102. What does a RNA virus look like in a histopathology?
    intracytoplasmic (in cytoplasm)
  103. What are different ways we can see the virus?
    • electron microscopy
    • immunostaining (immunofluorescence)
    • radial immunodiffusion RID
    • polymerase chain reaction (PCR)
  104. Where does the electron microscope usually see the virus?
    in tissue/discharge
  105. Who usually uses an electron microscope?
    research labs
  106. What does the electron microscope use to see the virus?
    electron rays
  107. How much does an electron microscope magnify?
  108. Why do we rarely culture viruses?
    because they can't grow in the environment
  109. What is the time frame for collecting infected tissue for a culture of a virus?
    • within 4 days of seeing signs
    • within 8 hours after death
  110. If we send a culture off to a lab how does it need to be sent?
    • kept cold
    • sent to lab quickly
    • viral transport medium used to keep bacteria under control
  111. What are the three main ways to isolate the virus?
    • cell (tissue) culture
    • embryonated eggs
    • animal inoculation
  112. How do we use cell culture to isolate a virus?
    inject sample into cell/tissue and then look for cytopathic effects
  113. What kind of cytopathic effects do we look for after a cell/tissue culture?
    • cell lysis
    • cell agglutination
    • inclusion bodies
  114. What are continuous cell lines?
    cells that divide indefinitely in vitro for a cell culture
  115. How do we use embryonated eggs to isolate a virus?
    inject virus into specific part and then look for lesions in the embryo
  116. How do we use animal inculation to isolate a virus?  What kind of animals do we use and why?
    • inject the disease into a live animal and then look for lesions
    • mice because they are small and don't take up a lot of space
  117. What do serological tests depend on?
    the type of virus
  118. What do serological tests measure?
    antibodies (indicates that the virus was present at some point in time)
  119. What are measured in serological tests?
  120. What are titers?
    how great the antibody response is
  121. How do we do a serological test?
    • take two different types of samples (acute - right when the animal is showing signs and convalescent - after being treated)
    • need to see a 4x increase in the titer for the convalescent sample
  122. What are the different serological tests?
    • hemagglutination
    • hemagglutination inhibition
    • complement fixation
    • virus (serum) neutralization
    • immunostaining - IFA
    • AGID (agar gel immunodiffusion)
    • immunoflurescence
    • ELISA
    • radioimmunoassay
    • immunodiffusion
    • complement fixation
  123. Which serological tests measure antibodies and titers?
    • hemagglutination
    • hemagglutination inhibition
    • hemadsorption
    • complement fixation
    • virus (serum) neutralization
  124. Which serological tests give us yes or no answers?
    • immunostaining - IFA
    • AGID (agar gel immunodiffusion)
    • ELISA
  125. What does IFA stand for?
    immunofluorescent antibody - this test is not necessarily just an antibody test, it tests for antigens too
  126. What are the two types of immunostaining?
    • direct
    • indirect
  127. What does direct immunofluorescence?
    • antibody to a specific virus is labeled with a fluorescent dye
    • if no virus is present then the fluorescent antibody washes away
  128. Is IFA direct or indirect?
  129. What does IFA use to test?
    flurescent microscope
  130. What shows up if positive in a IFA test?
    yellow-green fluorescence
  131. What do ELISA tests detect?
    • antigen
    • antibody
  132. Are ELISA tests sensitive?
  133. What indicates a positive result in an ELISA test?
    color change
  134. Are ELISA tests common in house tests?
  135. What are agglutination tests?
    reaction of particular antigen with antibodies to form visible aggregates
  136. What are different types of agglutination tests?
    • slide tests
    • card tests
    • tube tests
  137. How do we do an agglutination test?
    • start with particle that has antigen bound to it (RBCs, bacteria, latex)
    • add sample
    • if sample contains antibodies it will bind with the particle and agglutination will occur
  138. How do we do a hemagglutination test?
    • serially dilute sample (dilute more and more for each sample)
    • add sensitized RBCs
    • titer is the first tube where we see clumping (cloudy bottom) - this is the result of the test
  139. How do we do a hemagglutination inhibition?
    • combine sample and virus and allow to bind
    • add RBCs of appropriate species
    • if antibodies are present then RBCs will bind with the virus and there will be no agglutination
    • if antibodies are not present then the virus is free to attack RBCs and agglutination will be present
  140. Is the end result of the hemagglutination inhibition the opposite of the end result of a hemagglutination test?
    yes, the titer is the first tube where clumping is inhibited in the hemagglutination inhibition whereas the titer is the first tube where there is clumping for the hemagglutination test
  141. What is the latex agglutination test?
    • latex particles are coated with antibodies agglutinate when mixed with antigen
    • easy to perfom
    • fast results
  142. How do we do a virus neutralization in a cell culture?
    • incubate sample with virus
    • place in cell culture
    • look for effects on plate
    • if antibodies are present they neutralize the virus so it cannot infect cells
    • if antibodies are not present, the virus infects cells and causes visible damage
  143. How do we do complement fixation?
    • add antigen to sample
    • incubate
    • add complement
    • wait
    • add RBCs and anti-RBC serum
    • if no antibodies there is hemolysis because complement is available
    • if antibodies are present, then no lysis because complement was used by first Ag-Ab reaction, see red dot
  144. What is electrophoresis?
    • molecules separated by size and electric charge in a gel
    • can look at protein and nucleic acid pattern
    • nucleic acid bands are then stained
  145. What does Western blot test?
    check for specific antibodies
  146. What is western blot mostly used with?
  147. What is done before western blot?
  148. What does the southern blot identify?
  149. What does the northern blot identify?
  150. What test is considered the gold standard?
    polymerase chain reaction (PCR)
  151. What is another term for PCR?
  152. What does the PCR test do?
    • amplifies specific nucleic acids in sample
    • can compare base sequence to that of known pathogen
  153. Is the precipitation reaction test used often?
  154. What does the precipitation reaction test determine?
    antigen or antibodies in sample
  155. What does the Agar Gel Immunodiffusion use?
    special agar plate
  156. How does the agar gel immunodiffusion work?
    Ab and Ag in sample migrates in agar and we see precipitation line
  157. What test uses the agar gel immunodiffusion?
    • coggins test
    • johne's
  158. How do we do the radial immunodiffusion - RID?
    • antibody is mixed with agar and poured onto plate - uniform distribution
    • samples place in well, cut into agar and will diffuse out into agar
    • at point where equal numbers of Ag as Ab the complexes will precipitate out
    • size of precipitation ring correlates with amount of Ag in sample
  159. What does radioimmunoassay use?
  160. How do we do radioimmunoassay?
    • antibody to hormone is attached to filter
    • add serum to the sample
    • if hormone is present, it will bind to antibody on the filter
    • add radioactive iodine-labeled hormone
    • if hormone is not there, iodine binds to antibodies on filter
    • wash (all unbounded substances will wash away)
    • if hormone is present, no iodine remains
  161. What do we mainly use radioimmunoassay for?
  162. What are prions?
    • proteinaceous infectious particles
    • another class of infectious agents
  163. What do prions do?
    influences proteins in brain cells to turn bad
  164. Are nucleic acids involved in prions?
  165. What do prions cause?
    transmissilbe spongiform encephalopathies
  166. What are some tranmissible spongiform encephalopathies?
    • bovine spongiform encephalopathy (BSE) - mad cow disease
    • scrapie - sheep disease
    • chronic wasting disease of elk, deer, moose
    • feline spongiform encephalopathy
    • variant creutzfel-jakob disease (CJD) - mad cow disease in people
  167. How are spongiform encephalopathies spread?
    by ingestion
  168. How long are the incubation periods of prions?