Exam 1 Flashcards
What type of pathogen is canine parvovirus?
Non-enveloped virus
How is canine parvovirus persistent in the host?
The virus is shed in dogs within 4 to 5 days of exposure
Throughout the disease course and approximately 10 days following clinical recovery. It is not persistent in the host
Is canine parvovirus stable in the environment? If so, how long?
Can persists in the environment for months to years away from sunlight and disinfectants, refractory to most disinfectants (except Bleach)
Does canine parvovirus produce any toxins?
No
How does canine parvovirus enter cells?
Cell mediate endocytosis
Can enter most cells, replicates only in rapidly dividing cells
What is the tropism of canine parvovirus?
Replication in tissue cells that rapidly divide
Lymphoid, intestinal epithelium and in fetal tissue
Invades cells in S phase
Intestinal crypt epithelium and bone marrow hematopoietic precursors
What is the mode of entry for canine parvovirus?
Fecal-oral exposure
How does canine parvovirus structure affect the host response?
Targets and replicated in actively dividing cells
This results in leukopenia and lymphopenia and decreased number of active immune cells able to fight off the infection
What type of pathogen is salmonella?
Rod-shaped
Gram negative bacteria
How is salmonella persistent in the host?
Salmonella=umbrella term
Most common one is S. enterica
Both symptomatic and asymptomatic shedder depending on the species
Is salmonella stable in the environment?
Depends on the strain
usually few hours to several days on surfaces
Does salmonella produce any toxins?
O antigens are associated with the LPS chains that are found in the cell wall of all gram-negative bacteria
How does salmonella enter cells?
Depends on the species
Cell receptor mediated endocytosis is the most common
What is the cell tropism for salmonella?
Depends on the species
Intestinal epithelial cells and macrophages
What is the most common route for salmonella?
Fecal oral
How does salmonella affect host response?
Creates special membrane bound compartments within the host cells to shelter and protect it from host immune mechanisms
What type of pathogen is Rhodococcus equi?
Gram positive bacteria
What is the source of Rhodococcus equi infections?
It is a ubiquitous in the environment
But infected foals shed a tremendous amount of bacteria in their feces
What specific factor is associated with development of Rhodococcus equi?
Animals that produce little to no IFN-y are at an increased risk
What is the tropism of Rhodococcus equi?
Macrophages and replicates when there is a failure of the formation of the phagolysosome after receptor mediated engulfment
This results in an absence of the respiratory burst and destruction of the bacteria
Host factor
How might an animal be exposed to Rhodococcus equi but not develop disease?
Animals are exposed all the time, only those lacking the IFN gamma are at an increased risk
What demographic of horses commonly present with clinical signs of R. equi infection?
Foals 1-4 months old
What are some respiratory pathogens that infect adult horses and not foals?
Equine herpesvirus, equine influenza and equine arteritis virus
What type of pathogen are equine herpesvirus, equine influenza and equine arteritis virus ?
Enveloped viruses
Where is equine influenza typically found?
Maintained in the population by sporadic clinical cases and inapparent infections in susceptible horses
What specific factors is associated with the development of equine influenza?
The virus can mutate and create new strains in a population rapidly
Exposure of the virus to a naive population, particularly those that are immune suppressed
What are the common portal of entry for PRRS?
Direct contact (oral, respiratory, semen)
Indirect (fomites)
Is PRRS persistent within the pig?
Highly persistent in the pig but not in the environment because it is enveloped
What is PRRS tropism?
Macrophage cell
Viremia spread
Trojan horse spread within host
How does the characteristics of PRRS evade the immune system?
RNA virus
Generates mutations
What type of immune response is associated with PRRS?
Humoral (serum neutralizing antibodies) and cell mediated immune response
How does the structure of PRRS affect the immune response?
Enveloped virus
Development of neutralizing antibodies and or cell-mediated immunity have been related with clearance of PRRSV infection
How is the pathogenesis of Ascaris suum different with PRRS?
Ascaris sum is from direct trauma of the parasites migrating through the tissues resulting in secondary bacterial infection
While in PRRS the virus destroys macrophages which decreases the immune response
What are the common portals of entry for Ascaris suum?
Fecal-oral
Paratenic-earthworms and beetles
Is ascaris suum and indirect or direct life cycle?
Direct
Where do adult parasites of Ascaris suum establish infection?
Small intestine
Nematode attaches to the mucosa
What is resulting in the pig’s pneumonia from Ascaris suum
Migration of the L3 larvae through the lungs results in pneumonia
What type of systemic immune response is associated with Ascaris suum and
most helminth infections?
Induce a Th2 response that produces IL-5 and eotaxin that promote eosinophils
Eosinophils are the main leukocyte involved in attacking migrating parasites
What structure on the ascaris suum nematode results in this type of response?
Combination of molting, metabolic waste and migration that triggers the response
How does ascaris suum persists in the environment?
Third stage is infective to the pig
Chitinous structure of the shell protects it from environmental and chemical degradation
The protein coat makes the egg sticky so that it is not washed away
Is there any zoonotic potential of the sanctuary workers contracting Ascaris
suum from their vegetables?
Conflicting reports
May be zoonotic in those that are severely immunocompromised
What are the sources of infection and modes of transmission for canine influenza H3N8?
Direct contact via aerosol or droplets
Source are other infected dogs that are shedding
Once a dog has recovered from canine influenza H3N8 how likely is it that they will transmit it to other dogs?
Low
Dogs often shed disease prior to showing clinical signs
What is the risk of H3N8 influenza persisting for long period of time in the dog?
Low
Not persistent in the host and is not transmitted to humans and does not survive long in the environment
What is the anticipated period of shedding for H3N8 canine influenza?
Highest shedding is first 2-4 days during incubation period but can shed for up to 10-14 days
Is canine influenza H3N8 zoonotic?
No
What type of pathogen is equine infection anemia?
Retrovirus
Lentivirus-enveloped
What are the potential routs of entry for EIA?
Flies
Intermittent feeding, direct contact
What is the tropism of EIA?
Infects macrophages
How is EIA spread within the horse?
Infects macrophages resulting in viremia
What are the various manifestations of disease for EIA?
Acute: fever, non-specific signs, death
Chronic: Animal alternates between remission and disease state, animal is losing condition
Inapparent: Asymptomatic, reservoir for infection, stress may convert to acute form
How is EIA transmitted to other horses?
Flies are mechanical vectors
Direct contact
Are there alternative hosts for EIA besides the horse?
Members of the Equus genus
What does the cogging test test for?
Identifies antibodies for EIA antigen
What are two unique structural features of Roundworm?
Eggs are resistant to harsh environmental conditions
Eggs have pitted shell that is sticky from a protein coat that makes elimination from environment difficult
Transplacental transmission is one of the most important routs of infection to puppies
Single adult female can lay up to 85,000 eggs per day
What are two unique structural features of Porcine Epidemic Diarrhea Virus (PEDV)?
Specific natural host
Virus is enveloped RNA
Easily destroyed
Structural proteins of PEDV interact with viral genomic RNA to protein viral genome forming a nucleocapsid
N protein also perturb antiviral responses
How does roundworm enter the host and cause disease?
Egg ingested
Larvae released in intestines
Larvae migrate to other various organs where development is arrested
How does PEDV enter the host and cause disease?
Virus is excreted in feces
Oral infection due to contaminated food
Viral replication in the epithelial of the small intestine and colonic villi which causes malabsorption of the food and triggers an inflammatory response both leading to diarrhea
Is roundworm zoonotic?
Yes
Is PEDV zoonotic?
No
What are some strategies that break the cycle of transmission in roundworms?
Puppies and kittens dewormed at 2 weeks of age with deworming every 2 weeks until they are 4-8 weeks old
Fecal tests 1-2 times a year
One infectious virus unit
Virion
Lipid bilayer with attachment glycoproteins
Envelope
Are enveloped or naked viruses more stable in the environment?
Naked
Envelope is highly sensitive to drying and detergents
What is the difference between gram positive and gram negative bacteria?
Gram positive= Purple, thick peptidoglycan layer with techoic acids present
Gram negative= pink, lipopolysaccharide layer present