Mouse Pathology Review - DNA Viruses Flashcards
What kind of virus is Ectromelia virus
orthopoxvirus
What does ECTV stand for?
Ectromelia virus
Which mice are susceptible to ECTV?
What is a common presentation for these mice?
- C3H
- A
- SWR
- DBA
- CBA
BALB/c
They die acutely
Which mice are moderately resistant to ECTV?
SJL and AKR
Which mice are highly resistant to fatal infection of ECTV?
C57BL/6 mice
What is ECTV resistance based on?
Many genes, particularly variations in immune cells and cytokines?
Clinical signs of ECTV?
- vary from ruffled fur to prostration to death in a matter of hours
- Generalized rash that may last for weeks and leave scars
- subclinical in resistant strains
Common gross lesions of Poxvirus
- Alopecia, cutaneous erythema, erosions (rash), conjunctivitis, swelling, and Dry gangrene of extremities leading to amputation (ectromelia)
- swollen, friable livers w/ pinpoint white/red foci
- “Tiger stripe spleen” - splenic fibrosis -
- intestinal hemorrhage of upper small intestine
Histo lesions of ECTV
- *** Foci of coagulative necrosis in liver, spleen lymph nodes, Peyer’s patches, thymus
- ***erosive enteritis
- *** epidermal hyperplasia, hypertrophy and ballooning of epithelial cells
Strains resistant to ECTV will show more ____, while more susceptible strains will show more ___ of lympoid tissue
- hyperplasia
- necrosis
Types of Inclusion Bodies of ECTV
Type A: Eisinophilic, intracytoplasmic inclusion bodies in epithelial cells of the skin
— Marchal bodies
— epidermal skin cells, hepatocytes at periphery of necrosis
Type B: basophilic, intranuclear inclusion bodies potentially in any affected cell, but difficult to see
DNA viruses tend to make intranuclear inclusion bodies. What sets ECTV apart?
can be intracytoplasmic and intranuclear
Diagnosis of ECTV
- ELISA
- Histopathology
- PCR, immunofluorescence
- Hemagglutination assay (HAI)
Pathogenesis of ECTV
Skin invasion via trauma to skin -> local invasion and multiplication -> replication in regional LN -> hematogenous spread to major organs (primary viremia) -> replication in spleen and liver -> secondary viremia -> targets sites like skin, kidney, lung, intestine, and other organs and causing focal infections
Transmission of ECTV
- Direct contact and cutaneous trauma (NOT contaminated animal products)
- Not highly contagious
Repro concerns for ECTV
- maternal antibodies protect against disease, but not infection
- ECTV infects placenta and fetuses, leading to fecal death
Prevention and Control of ECTV
- Decontamination: viral particles stable in environment
- Quarantine and/or Depopulation
- Vaccination w/ vaccina virus (will not always prevent infection but will lower it)
Research impacts of ECTV
Potential massive loss of life in susceptible strains
Types of Mouse Adenoviruses
- Murine mastadenovirus-1 (MAdV-1)
- Murine Mastadenovirus-2 (MAdV-2)
typical presentation in of MAdV-1 and MAdV-2 in immunocompetent mice
subclinical
Which cells does MAdV-1 target?
- Monocyte-macrophage lineage
- Renal distal tubular cells, respiratory epithelium, adrenal cortical cells, microvascular endothelium
Which cells are important for clearing MAdV-1 infection?
B-cells
Which cells are important for fighting disease and what else can they do?
T-cells; can also contribute to pathology (T-cells killing the virus may determine severity of clinical disease)
How is MAdV-1 shed?
- in the urine
- Direct contact and nasal secretions
Which strains develop hemorrhagic encephalitis with MAdV-1 infection?
- C57BL/6
- DBA/2
- SJL
- SWR
- CD-1
Which strains develop disseminated disease with hemorrhagic encephalomyelitis?
B6-Rag1
Which strains develop a fatal disseminated disease with focal hemorrhagic enteritis and microvascular fatty change (Reye’s-like syndrome)?
BALB-scid and BALB-scid/beige
Which strains develop progressive wasting, disseminated infection, and duodenal hemorrhage?
Athymc C3HH3N-nude
Which type of brain matter is more affected by MAd-V1?
white matter – “a lot of it is being ‘unable to relax’”
Clinical signs of MAdV-1
- runting
- Dehydration
- CNS signs from white matter injury
— rigid tails, hypermetria, paraphimosis, ataxia, urinary bladder distention
Gross lesions of MAdV-1
- thymic involution
- necrosis in liver, spleen, and other organs
Histo lesions of MAdV-1
- endothelial necrosis and hemorrhage
- Intranuclear inclusions in foci of necrosis and hemorrhage in vary types of organs
T/F Rats will seroconvert and are susceptible to MAdV-2
False; they will not seroconvert
How is MAd-V2 shed?
in the feces
Tissue tropism of MAdV-1
multiple: intestine, salivary glands, spleen, brain, myocardium, brown fat
Tissue tropism of MAdV-2
enterotropic
Prevalence of MAdV-1 in vivaria
historic only
Prevalence of MAd-V2 in vivaria
natural infection in modern vivaria, low
Clinical signs in natural infection of MAd-V1
none described
Clinical signs in natural infection of MAdV-2
runting of suckling mice
Clinical signs in experimental infection of MAdV-1
severe with pup infection: runting, lethargy, scruffy, death in 10 days, wasting disease in nude mice
Clinical signs of experimental infection of MAdV-2
Absent except for runting of suckling mice
Clinical signs of MAdV-2
Rare, aside from runting of suckling pups
Histopathological findings of MAdV-2
intranuclear inclusions in intestinal epithelium of infant mice > adult mice (apical location, rather than basal)
Transmission of MAdV-2
shed in feces
Diagnosis of MAdV
- Serology
- Intranuclear inclusions in intestine are pathognomonic for MAdV-2
Prevention and Control of murine adenoviruses
- Serologic monitoring
- Segregate infected colonies until infection is over (MAdV-2 only)
- Rederivation
“MAV1 - either suck it up and accept its presence or cull”
“MAV-2 - self-limiting, so can segregate colonies”
Research concerns of MAdV
primarily pathogenicity impact on immunodeficient mice
DDx for ECTV
causes of hepatitis, such as
- MHV vs Tyzzer’s dz vs salmonellosis vs other
Skin lesions
- bite wounds vs. trichotillomania vs. hypersensitivity vs. other forms of dermatitis
gangrene or digit / tail amputation
- trauma vs. ringtail
Which subcategory of herpesvirus is the worst?
alpha-herpesviruses
What are the three subcategories of herpseviruses
- alpha-herpesviruses
- beta-herpesviruses
- gamma-herpesviruses
What is the other name for Murine herpesvirus 1?
Mouse Cytomegalovirus (MCMV)
Clinical signs of natural infection of MCMV?
subclinical in lab animals
Clinical signs of Experimental infection of MCMV?
multisystemic necrosis, inflammation, and death of neonatal mice
Histopath lesions of MCMV?
- enlarged cells with intranuclear and intrcytoplasmic inclusions (nucleus is easily 10x normal size), particularly in the salivary glands, esp. the submandibular gl.
- Lymphoplasmacytic infiltrates
Strains resistant to MCMV
- C57BL/6
- B10
- CBA
- C3H
Resistance is associated with the H-2k haplotype
Strains susceptible to MCMV
- BALB/c
- A
Will see worse necrosis and inflammation in organs of T-cell-deficient mice