• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/32

Click to flip

32 Cards in this Set

  • Front
  • Back
T/F
The majority of B.abortus induced abortion in cows occur during the second trimester of pregnancy
True
T/F
B. abortus is an extracellular pathogen. Humoral immunity provides protection against the pathogen
false - it is intracellular. Humoral immunity protects against abortion, not the pathogen.
T/F
B.abortus can penetrate intact mucosa and skin
False - it can penetrate the mucosa, not the skin.
T/F
During the second gestation of a cow that had a previous B.abortus-
induced abortion, it would give birth to health calves.
True
How does Brucellosis stain? What shape are they? Are they spore forming?
• Brucella are small gram-negative coccobacilli, nonmotile of alpha-proteobacteria group. Does not form spores.
• Grows in any high quality peptone-based media enriched with blood or serum.
How does Brucellosis clinically present?
Tachycardia
Abdominal pain, enlargement of liver and spleen
How is Brucellosis shed? What populations are susceptible?
• Chronic infection in farm animals
• Is shed in urine, milk, therefore infections are common in farmers, veterinarians, laboratory workers. B.canis has infected a few dog breeders.
• Among animals, infection by conjunctival and genital mucosa, skin, respiratory, semen, contaminated abortion fluids, tissues.
• B.abortus, is the most common species in the US!
Are Brucella genomes highly conserved?
In what genes does the majority of the diversity between species lie?
• The genomes of B.melitensis, B.suis and B.abortus have been sequenced
• 90% gene sequenced share 98-100% homology. Suggest that the genomes are very conserved
• 33 different regions differ between B.abortus and others: 22 B.suis, 11 B.melitensis. The majority of the diversity is in pathogenicity islands; which are DNA acquired horizontally.
What are the four routs of transmission of brucellosis to humans?

What are some risk factors in contracting it?

What are the routes of transmission to animals?
• Routes of Transmission to humans:
1- skin abrasions
2- ingestion of non-pasteurized products
3- aerosol
4- inoculated in the conjunctival sac

• Person-to-person transmission rare
• Rarely seen in HIV-1 infected patients
• Risk factor: use of anti-acids, H2-receptor antagonist.

• Routes of Transmission to animals:
Oral
Reproductive tract
What is the pathogenesis of brucella?
• Brucella infects orally and localizes in the lymph nodes in the nasopharyngeal area. Then disseminates. The pregnant uterus is particularly susceptible to Brucella.
• Brucella localizes in the trophoblast of placenta, where it inhibitis secretion of chemokines and inflammatory cytokines
• Infection spreads to fetus. Most have pneumonia
• Mechanisms of abortion:
1- Interference with fetal circulation (vasculitis)
2- endotoxin
3- fetal stress
What are the factors that increase the pathogenicity of brucella?
Type 4 secretion system is necessary for intracellular survival.

Establishment of the infection through the digestive tract requires Urease and bile salt hydrolase, and LPS (O antigen) - allows brucella to cross the barriers into the intestinal tract.
Brucella is an intracellular bacteria. What type of cell does it live within?
How does it pull this off?
Macrophages

1. does not trigger O 2 burst (doesn't let vacuole acidify)
2. P-L do not fuse
3. Prevent Apoptosis
Where is it hypothesized that Brucella picked up its type IV secretion system?
A plant bacteria
What are the humoral and cell-mediated host immune responses to Brucella?
Humoral: IgM and IgG can be protective. antibodies offer partial protection. Even if an animal harbors a chronic infection of brucella, they won't keep having abortions.

Cellular: Effective immunity, CD4+ T cells, NK cells
Is there a vaccine for Brucella abortus?
vax works for brucella abortus, but none are 100% effective.

Protect against abortion (<transmission) but not against infection

Vaccination is not practiced for B.canis and B.suis
How is Brucella diagnosed, treated and controlled?
• Staining and culture
• ELISA (blood, milk, semen)
• PCR (differentiation from vaccine strains)

• Treatment of cattle is not practical
• Detection and slaughter

• Control: Immunization at calf age, testing and removal
How does Tularemia gram stain? Is it motile? What shape is it?
Francisella tularensis

Gram-negative, non motile, coccobacillus
What are reservoirs for Francisella tularensis?
• Is believed to be maintained in the
environment (squirrels, rabbits, rats, etc)
• Presence in water, associated with amoeba
• Vectors: mosquitos Aedes, Culex,
Anopheles or ticks, like Ixodes
What makes F.tularensis LPS a pathogenic factor?
LPS has phase variation. The LPS phase variation is important. Disguises the bacteria from the host.

WT encapsulated bacteria are serum
resistant
Does Tularemia have a seasonality? What populations are more susceptible?
• Is more frequent from June to August (tick season), and December (hunting associated)
• Laboratory worker, farmer, veterinarian, sheep worker, hunter, cook are most affected
How is Tularemia transmitted?
• Animal contact: skinning, eating
• Airborne transmission: contaminated water, dust or hay
• Carnivorous animals carried it on claws or mouth (mechanism of domestic cat transmission)
• Ticks predominates in the Rocky Mountains
• Biting flies in California, Nevada, Utah
• Mosquitoes in Sweden, Finland and Soviet Union
• 13 species of ticks. The dog tick
(Dermacentor variabilis) and the wood-tick (Dermacentor andersoni)
What domestic animals are infected with tularemia?

What are the clinical signs?
• Sheep, Horses, Pigs
• Dogs and Cats can be infected without symptoms
• Transmission in outbreaks is frequently related to tick infestation or fly bite

Clinical signs are not well documented. Apathy followed by fatal septicemia.
Which bacteria has type IV pili, brucella or tularemia?

What is the function?
Tularemia.

Brucella has type IV secretory system.

• What is the function? Binding to mucosal surfaces?
• Macrophage infection?
How is tularemia diagnosed?
• Signs are non-specific. Suspect tularemia if tick infestation occurs in severely ill animals
• Wright’s or Giemsa
• Serology (> 1:80), scrapings from ulcer, lymph node aspirate
• Culture on blood agar with cysteine, 37C
How do you control Tularemia?
• Ectoparasite control.
• Recognition of tularemia in the ecosystem
• Sources of infection: water, contaminated carcasses, excreta of wildlife species
• Prevention of hunting by cats and dogs
Does tularemia infect domestic animals?
Although tularemia is mainly a disease of rodents, it occurs in domestic animals:
• Contact with infected food (dead rabbit)

• Infected vectors: ticks, mosquitoes, deerflies.
• Cats and sheep are the most frequently infected
What are the subspecies of F. tularensis?

IMPORTANT ONE
Three Sub-species:
1- F.tularensis ssp tularensis (type A)
2- F.tularensis ssp holartica (type B)
3- F.tularensis ssp mediasiatica
Which hosts are susceptible to Tularemia infection?

IMPORTANT ONE
broad host range (190 sp mammals, 23 of birds, 3 of amphibians, 88 of invertebrates)
When phagocytosed by macrophages, Francisella lives ( ) in a vacuole, ( ) in the cytoplasm?

IMPORTANT
In the cytoplasm.

Escapes the phagosome!!!

Unique
Does Francisella has a pathogenicity island? Is it important for virulence?

IMPORTANT
Yes

Pathogenicity island involved in virulence.
Gene duplication, which suggests importance.
Is nitric oxide important for host defense against Francisella? ( )Yes ( )No?

Is IFN-gamma? ( ) Yes ( ) No?

IMPORTANT
Yes to the Nitric Oxide. But I'm not sure how!

And...no to the IFN? This is what is says in the lecture:
IFN-gamma, different results according to macrophage population
How do one treats tularemia?

IMPORTANT
Aminoglycosides
Fluoroquinolones
Tetracycline have been used in animals