Midterm 2 - Lecture 9 Flashcards

1
Q

What is calf scours also known as?

A

Undifferentiated diarrhea in new born calves

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2
Q

Calf Scours

A
  • major economic losses
  • multiple agents cause the disease
  • related to interactions btw host, agent, and enviro
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3
Q

Signs of an E.coli agent for calf scours

A
  • effortless passing of yellow to white feces
  • releases a toxin that binds to the cell to increase all the water into the intestine = dehydration
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4
Q

Signs of a Salmonella agent for calf scours

A
  • similar to E.coli; yellow to white feces, possible blood
  • obliterates the villi (which is the barrier to pathogens and bacteria coming in)
  • ‘gut buster’
  • zoonotic
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5
Q

Signs of a Coccidia agent for calf scours

A
  • blood-tinged diarrhea
  • ‘drills holes’ in the mucosa for bacteria to come in
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6
Q

Signs of a Cryptosporidium for calf scours

A
  • watery brown to light green feces, blood and mucus
  • zoonotic
  • tiny protozoa
  • defaces brush border around each villi
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7
Q

Contributing factors for calf scours

A
  • cold, wet weather
  • sanitation: crowded housing = sick animals in close proximity
  • nutrition of both dam and calf
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8
Q

Medical treatment and prevention of calf scours

A
  • stress free clean enviro
  • treat with antimicrobial to protect against secondary infections
  • fluid and electrolyte therapy
  • colostrum
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9
Q

Management and prevention of calf scours

A
  • separate healthy cow/calf from sick to clean pasture
  • good sanitation of equipment and handlers
  • healthy cows
  • vaccinate cows prior to calving; antibodies passed to calf in colostrum
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10
Q

What is shipping fever also known as?

A

Bovine Respiratory Disease

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11
Q

What is Bovine Respiratory Disease?

A
  • shipping fever pneumonia is associated with the assembly into feedlots of large groups of calves from diverse geographic, nutritional, and genetic backgrounds
  • typically seen in feeder calves 7-10 days after feedlot assembly
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12
Q

What are the primary infection agents of shipping fever?
know how to spell these

A

1) insult with viral pathogen
- Bovine Herpes Virus-I
- Bovine Viral Diarrhea Virus
- Bovine Respiratory Syncytial Virus
- Bovine Parainfluenza Virus

2) and/or:
- Mycoplasma sp

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13
Q

What agents induce a secondary infection following shipping fever?

A
  • Mannheimia hemolytica
  • Histophilus somni
  • Pasteurella multocida
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14
Q

Innate immunity

A
  • generalized process, no immunological memory
  • composed of 2 components:
    1. non-cellular = barriers, enzymes/proteins, secretion, reflexes, complement cascades
    2. cellular = antigen-presenting cells, macrophages and granulocytes, NK cells, cytokine
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15
Q

Adaptive immunity

A
  • specific and has immunological memory
  • B cells: produce antibodies
  • T cells: control adaptive immune response
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16
Q

5 strategies to induce disease evasion of innate immunity

A
  1. Interference of physical barrier (lung)
    - respiratory epithelia cells provides mechanical, chemical, and microbial barriers
  2. Interference with phagocytosis
    - phagocytosis is an important component of innate immune defense
  3. Interference with intracellular killing
    - phagocytic cells produce toxin compounds important for destroying bacteria
  4. Interference with INF (interferons)
    - INF: antiviral and induce/enhance immune fxns; reduce viral replication and cell-cell transmission
  5. Regulation of Apoptosis
    - viral-induced cell death important to prevent viral proliferation cell-cell transmission
17
Q

Agent that infers with the physical barrier

A

Bovine herpes-I
- infects respiratory epithelium and goblet cells
- results in injury of epithelial barrier of epithelium and associated lymphoid tissue
- allows bacterial pathogens to invade from nasopharynx

18
Q

What agent interferes with phagocytosis?

A
  • Histophilus (Hemophilus) somni: when engulfed by phagocytic cells it induces apoptosis and reduces capacity of phagocytosis
19
Q

What agent interferes with intracellular killing?

A
  • Mycoplasma bovis: impairs intracellular signaling to alter a myeloperoxidase enzymatic response
20
Q

What agent interferes with interferons?

A

Bovine Viral Diarrhea Virus
- the amino-terminal of BVDV inhibits IRF3 from binding to INF promoter

21
Q

What agent interferes with the regulation of apoptosis?

A

Bovine Herpes Virus-I
- will induce apoptosis in epithelial cell at the end of viral replication = ensures increased numbers of viral particles

22
Q

What are 7 strategies to induce disease evasion of adaptive immunity?

A
  1. Suppression of lymphocyte proliferation
  2. Induction of humoral and cellular immune tolerance
  3. Down regulation of MHC-II molecules
  4. Inhibition of antibody production and effectiveness
  5. Loss of CD4 T cell fxn: loss of CD4 molecules will alter immune fxn
  6. Interference with cytotoxic T cell fxn
  7. Shut down protein synthesis
23
Q

What agent suppresses lymphocyte proliferation?

A

Bovine Viral Diarrhea Virus
- infects antigen-presenting cells and will reduce the clonal expansion of CD4-T cells

24
Q

What agent induces humoral and cellular immune tolerance?

A

Bovine Viral Diarrhea Virus
- Mucosal disease = non-cytopathic form infects fetus and there is a reductions in INF production, the virus then replicates in tissues unrestricted
- Cytopathic form: Calf now has a lot of virus to induce immunotolerance (recognize as self) and ‘tolerized CD4-Tcells’; exposed to cytopathic form and cannot mount an immune response

25
Q

What agent induces down regulation of MHC-II molecules?

A

Leukotoxin of Mannheimia hemolytica
- will decrease the expression of MHC-II molecules on antigen-presenting cells, allowing the organism to grow in tissue
- MHC-II needed to activate CD4-T cells and provide help to B cells

26
Q

What agent inhibits antibody production/effectiveness?

A

Histophilus somni
- secrete proteins that bind to IgG2 antibodies in a non-specific manner

27
Q

What agent induces the loss of CD4 T cell fxn?

A

Bovine Herpes Virus-I
- will induce the loss of CD4 molecules on lymphocytes and subsequent induction of apoptosis of these lymphocytes
- there is CD4 lympholysis in peripheral blood and lymph nodes

28
Q

What agent interferes with cytotoxic T cell fxn?

A

Bovine Herpes Virus-I
- produces proteins that inhibits cellular processes and down regulates MHC-II and antigen presented in MCH-I molecules and thus escape CTL induced cell death
- MHC-I molecules are needed for CD8 T cells to eliminate virally infected cells

29
Q

What antigen shuts down protein synthesis?

A

Bovine Herpes Virus-I
- produces ‘virion host shut-off protein’ that reduce protein synthesis by degrading mRNA of cellular protein
- protein synthesis is needed to generate molecules used in immune fxn

30
Q

What strategy is used to induce disease change in the pathogen?

A

Antigenic variation (shift)
- organisms can change the structure of surface membranes

31
Q

What agent induces antigenic variation?

A

Mycoplasma bovis
- can reduce and shorten surface proteins and if the immunity in the calf wanes the surface proteins will revert back to its original form