Mouse Pathology Review - RNA Viruses Flashcards
What is the clin path abnormality associated with Lactate dehydrogenase-elevating virus (LDV)
elevation of LDH (specifically, LDH-V)
LDV is typically ____, but _____ has occurred with ______ C58 and AKR mice inoculated with LDV
- subclinical
- poliomyelitis
- immunosuppressed
Transmission of LDV
- mechanical transfer from bite wounds - results in lifelong viremia
- inoculation of mice with contaminated animal products (cell lines, transplantable tumors, or serum) is probably most common source of induced infection
Sources of LDV infection
- wild mice
- transplantable tumors
- hybridomas
Detection of LDV
- PCR is a preferred diagnostic.
- LDH enzyme assays are often false positives
Prevention of LDV
- Monitor cell lines that tumors are being transplanted from
- Keep wild mice away from colonies
Research complications of LDV
- adverse effects on immunological studies
— reduced antibody production, transient thymic necrosis, lymphopenia, suppression of cell-mediated immune response, and enhance/suppress tumor grwoth
LDV infection is subclinical except for ____ and ____, and results in a _____
- Immunosuppressed C58 mice
- Inoculated AKR mice and ICR-scid mice
- paralytic syndrome
Why is LCMV considered a significant pathogen?
It’s Zoonotic, and causes symptoms of meningitis in humans
What is LCMV
Lymphocytic choriomeningitis virus
What is the natural reservoir host of LCMV
wild mice
Which animal is not naturally infected with LCMV?
the Rat
What is the amplifying host of LCMV?
hamsters
What ABSL level should be followed when working LCMV-infected hamsters?
ABSL 3
What ABSL level should be followed when working with LCMV-infected mice?
ABSL 2
What is the primary source of LCMV in humans?
hamsters
Transmission of LCMV
- via aerosol and direct contact
- nasal secretions
- urine
- saliva
What is the typical infection mode of Immunocompetent adult lab mice with LCMV
Adult mouse inoculated with virus-infected biologicals -> self-limiting and subclinical disease -> clearance of virus -> now a persistently infected mouse
Explain what “Late disease” is in regards to LCMV
Pups infected in utero or as neonates are immune tolerant of LCMV, but that immune tolerance is very specific to LCMV. Mice develop antibodies to other pathogens. Immune tolerance breaks down late in life (after breeding age) and the mice lose weight and die. In utero infection can cause low level loss of fetal mortality and cannibalism of infected pups. Infection of older pups can result in viral clearance or death
What may be seen with LCMV “late disease?”
Lesions are characterized by formation of immune complexes and associated inflammation. Renal glomeruli and choroid plexus are most severely affected
What happens with intracerebral inoculation of LCMV in immunocompetent mice
- an immune-mediated lymphocytic choriomeningitis develops 5-6 days post-inoculation -> May see sudden death or any of the following: ruffled fur, hunched appearance, motionless, neuro deficits (tremors when suspended by tail (and sometimes spontaneously), colonic convulsions, rear leg extensions) -> death or recovery in several days
What happens with peripheral inoculation with viscerotrophic strain of LCMV in immunocompetent mice
- subclinical
or - result in clinical signs (ruffled fur, conjunctivitis, ascites, somnolescence, and death). -> if mice survive, recovery may take weeks. Those that survive may have immune exhaustion due to lymphodepletion.
Diagnosis of LCMV
- Serology of immunocompetent mice (carrier mice may have false negatives)
- PCR on biologic products and cell lines
- Sentinel testing
- Histology
What are the four forms of LCMV
- Natural infection, self-limiting and subclinical in immunocompetent mice
- “late disease” (L) - late-onset disease w/ immune complex glomerulonephritis in previously asymptomatic carriers (9-12mos. old)
- Intracerebral inoculation (C) - ass. w/ neurotropic or cerebral form include sudden death (M for mortality) 5-6 days after inoculation
- “Visceral form” (V) - results from peripheral inoculation w/ viscerotropic strains - may be asymptomatic or have nonspecific signs
What is the pneumonic for LCMV
L - “LATE disease”
C - “IntraCEREBRAL inoculation”
M - “MORTALITY and runting in neonates”
V - “VISCERAL form in adults inoculated with ‘viscerotropic strain’”
Which mouse silently harbors LCMV?
Nude mouse
- LCMV multiples in DCs, B cell, and macrophages; T-cells are resistant
- Virus elimination and virus-associated immune injury are T-cell mediated. Athymic nude mice don’t have T cells or B cells
Research implications of LCMV
- sick mice
- Reduced reproductive efficiency
- Deaths in colony
- Contaminant of biological product derived from mice
- ZOONOTIC
Prevention and control of LCMV
- adequate testing of animals and animal products are the best way to prevent entry. Euthanize all hamsters and immunodeficient mice that test positive
Test and cull, depopulation
Differentials of LCMV
- Mouse hepatitis virus
- Mouse Encephalomyelitis virus
- Meningoencephalitis from bacterial infections
- Toxins
- Trauma
- Neoplasia
What are the two viruses of the Paramyxoviridae family that infect mice?
- Sendai Virus
- Pneumonia Virus of Mice (PVM)
Prevalence of SV in Vivaria / contagion
- rare to absent
- Very contagious!
Prevalence of PVM in vivaria / contagion
- Declining
- not very contagious
Species susceptible to SV
Mice, rats, hamsters, Guinea pigs
Species susceptible to PVM
mice, rats, hamsters, other rodents +/- rabbits
Clinical signs due to natural infection of SV in immunocompetent animals
- Chattering, dyspnea, hunched posture, weight loss, ocular crusting, death.
- Neonates commonly die (lethal infection)
Clinical signs due to natural infection of PVM in immunocompetent animals
Subclinical
SV tissue tropism
- respiratory epithelium
- *** Type II pneumocytes
PVM tissue tropism
Respiratory tract
Does SV cause wasting in nude mice?
yes
Does PVM cause wasting in nude mice?
yes
Gross lesions of SV in immunocompetent animals
- partial to complete consolidation of the lungs
- Bronchointerstitial pneumonia with atelectasis, centered on lung hilus
- 2° bacterial infections resulting in bronchopneumonia
Gross lesions of PVM in immunocompetent animals
none!
Susceptibility to SV varies by mous strain and results from difference in _____ _____ function.
mucociliary apparatus
Mice strains susceptible to SV
- DBA/2