Virus Flashcards
Mousepox
ECTV, orthopoxvirus
ECTV resistance
A, BC, DBA/1, DBA/2, and CBA susceptible, B6 resistant (natural);
BALB/c, A, DBA/2, C3H susceptible, AKR and SJL moderate, and B6 highly resistant (experimental)
Transmission: mousepox
Direct contact and skin abrasions, highly stable at room temp, virus excretion lasts for around 3 weeks

Ectromelia, intracytoplasmic inclusions

ECTV - White spots on liver (necrosis), splenic necrosis - mosaic pattern
Inclusion bodies - ECTV
A type (Marchal body) - well demarcated, acidophilic, primarily in epithelial cells of skin or mucous membranes
B type - basophilic, found in all ectromelia-infected cells (difficult to visualize)

ECTV vaccination “Take”, uses hemagglutinin-deficient strain to scarify skin on dorsum of tail
ECTV diagnosis
Serum from vaccinated mice may react by ELISA but should not react with HAI
Herpesvirus - mouse
Subfamily - betaherpesvirinae, genus Muromegalovirus, two species - MHV1 (MCMV) and MHV3 (MTV)

MPV
MCMV
Betaherpesvirus, subclinical in adult, lethal in neonates
Persistent infection - saliva, urine, tears
Limited to enlarged cells with eosinophilic intranuclear/cytoplasmic inclusions with lymphoplasmacytic interstitial inflammation, esp. in cervical salivary gland
Can suppress immune responses
MTV
Mouse thymic virus
Natural infection is subclinical
Excretion of virus in saliva
Severe diffuse necrosis of thymus and lymphoid tissue with tropism for CD4+ T cells, intranuclear inclusions
MVM
DNA, protoparvovirus, species - rodent protoparvovirus 1
VP1/2 are virus specific for differentiation between MVM and MPV
Natural infection - subclinical
Mouse is only known host, oronasal exposure, not PI

MAV B
Intranuclear adenoviral inclusions in SI of infant mouse
Vacuolated enterocytes (typical of normal neonatal mouse bowel)
MPV-3
Close to a hamster parvovirus isolate
MPV
Causes PI
Enters through mucosa of intestine - virus replication
No histo
Provoke immune dysfunction
MAV-1
Nonenveloped DNA virus
Murine mastadenovirus A (or FL)
Can cause severe dz in infant mice, wasting, death, necrosis (brown fat, myocardium, adrenal cortex, salivary gland, kidney), intranuclear inclusions
Low prevalence
MAV-2
Murine mastadenovirus B (K87)
Enterotropic and responsible for virtually all naturally occuring infections, usually subclinical
Amphophilic, intranuclear inclusions in intestinal epithelium (distal SI)
MAV-2 antigen should be used for serological detection regardless of assay
PyV
Polyoma virus, DNA, Murine polyomavirus
Tumor induction, neuro dz, and wasting can occur in immunodeficient mice
Transmission via respiratory, PI in infant mice
B6 most resistent to PyV oncogenesis
Tumors of both epithelial and mesenchymal origin
K virus
Absent in modern times, vascular endothelium, PI

SV
Consolidation
Necrotizing bronchiolitis
Intersitial pneumonia
LDV
Lactate dehydrogenase-elevating virus (only LDH-V isotype)
RNA virus, Arteriviridae, PI, wild mice
Subclinical, poliomyelitis
Transmission through mechanical transfer (bite wounds)
Selectively targets F4/F8-positive macrophages
Homozygousity for the Fv-1n
Fv-1n
Permits replications of endogenous N-tropic ectropic murine leukemia virus
LCMV
Arenaviridiae, RNA
Dz due to host immune response
ZOONOTIC
Natural infection - “late disease”, weight loss, death
Exp. infection - Sudden death, runting, neuro
Viscerotropic - conjunctivitis, ascites, somnolesscence, death
Mice, hamsters, GP, NHP
In adult mice with acute LCMV virus multiples in DCs, B cells, macrophages (T cells resistant)
SV
Parmyxovirus (similar to human PI-1), RNA
Hunched, piloerection, weight loss, dyspnea, chattering, ocular discharge - more lethal in suckling mice
Transmitted by aerosol, highly contagious, morbidity 100%
B6 highly resistant, DBA/2 highly susceptible
Rats, hamsters, GPs
Can “burn out”
SV - pathology
Gross - partial to complete consolidation, meaty, plum-colored
Histo - targets airway epithelium and type II pneumocytes, bronchopneumonia and interstitial pneumonia

EDIM - swelling of enterocytes at tips of villi
PVM
Murine pneumonia virus, RNA, Pneumovirus, paramyxoviridae
Natural infection - subclinical, acute, self-limiting in immunocomp., seropos animals are immune or in final stage of acute infection
Mice, rats, hamsters, rabbits
Intimate contact required for transmission, environmental inactivation is rapid
More mild than SV
Can exacerbate pneumocystosis
Reovirus - mouse
Reovirus per se (Mammalian orthoreovirus) and murine rotavirus (Rotavirus A, EDIM)
Mammalian orthoreovirus (1,2, and 3)
3 is associated with naturally occuring disease
Acute dz - 2 wks, adults - subclinical
Emaciation, abdominal distension, steatorrhea (oily, matted hair), icterus, neuro, partially alopecic
Enter through infecting intestinal epithelial cells (M cells) that cover Peyer’s patches
Liver/intesine, papillary muscles of left ventricle, brain

MHV, Necrosis, inflammation, syncytium in liver

Hepatitis, syncytia in SCID mouse

MHV, proliferative colitis in chronically infected athymic mouse

MHV, Small intestine of neonatal mouse, villi attenuated and marked syncytia
Rotavirus
ds RNA, wheel-like ultrastructure

MHV antigen in colonic mucosa of an athymic mouse chronically infected with enterotropic MHV
EDIM
Group A rotavirus
Replicates in differentiated epithelial cells of the small intestine by budding into cisternae of endoplasmic reticulum
Will still see milk in stomach
Can burn out w/ cessation of breeding
EDIM - Clinical Signs
Mice
Bloated abdomens, fecal soiling of perineum, low mortality, transient weight loss
MHV
Coronavirus, RNA, radially arranged peplomers (spikes)
Enterotropic (intestinal) and polytropic strains (respiratory, multi)
Can be differentiated by neutralization tests that detect strain-specific spike (S) antigens
SYNCYTIUM
Respiratory/oral
MHV - Epizoo
Infection in immunocompetent is self-limiting
Will not develop cross-immunity to other strains
DBA/2 mice highly susceptible to MHV-3, A/J resistant
MHV - Pathology
Polytropic - replicate initially in nasal mucosa, yellow-white foci of necrosis in various tissues
SYNCITIA at margins, acute neocrotizing encephalitis/mengingo
MHV - other
Often subclinical so serology
Can burn out in immunocompetent adults at cage level
Remains infectious up to several days in environment
TMEV
Theiler’s Murine Encephalomyelitis Virus
Cardiovirus, picornaviridae, RNA, nonenveloped
Prototype strains - TO (Theiler’s original), FA, DA, and GD VII (George’s disease)
Neuro disease - flaccid posterior paralysis
Acquired by ingestion, replicates in intestinal mucosa
Cardiovirus - murine
Picornaviridae family
EMCV
TMEV
Max Theiler
Discovered TMEV during experimental studies of yellow fever virus in mice
Prototype strains - TO (Theiler’s original), FA, DA, and GD VII (George Martine - George’s Disease)
MNV
nonenveloped RNA, caliciviridae (family)
Resistant to environmental infection
Species-specific
High mortality in interferon receptor and STAT1 null mice, RAG1 cannot clear
Fecal-oral
Tropism for macrophages and dendritic cells
Suceptible mice may develop splenomegaly and multifocal pale spots in liver
Neonatal mice are resistant to infection
MGH strain - TMEV
Isolated from laboratory rats and is pathogenic in mice and rats after experimental innoculation
Hantavirus
RNA virus, Bunyaviridae (family)
NOT arthropod borne
Infection is lifelong
ZOONOTIC (rats)
Retrovirus - mouse
MMTV and MLV
RNA, retroviridae
MMTV - LTR region contains additional Sag
Bittner MMTV and Gross, Friend, Moloney, and Rauscher’s MLV
DBA, C3H, and GRS carry Mtv1 or Mtv2 loci - encode infectious virus
AKR mice develop 100% prevelance of thymic lymphoma between 6-12 months, BALB/c commonly develop multicentric lymphoma
MMTV can induce lymphomas in SJL
Noninfectious retrovirus related retroelements
IAP, VL30, MusD, and ETn
Exogenous viruses
Horizontally transmitted, replication-competent
Endogenous virus
Closely related to exogenous viruses, encoded within mouse genome, transmitted by Mendalian inheritance
Ecotropic virus
If endogenous retrovirus is still infectious to other mouse cell targets
Xenotropic virus
No longer infectious to mouse cells, but can infect other species
Astrovirus
nonenveloped, ss RNA, Mamastrovirus
Associated with human gastroenteritis
MuAstV
No clinical signs
Detected in most common immunocompromised strains
ECTV vaccination
IHD-T strain of vaccinia is used to scarify skin on the dorsum of the tails
“Takes” should occur in previously uninfected mice, but not in infected mice

Interstitial pneumonia in a DBA mouse infected with SV

Lungs from a DBA mouse infected with SV. Note consolidation of lung tisuse at hilus.

Necrotizing bronchiolitis in a DBA mouse affected with SV

Severe interstitial pneumonia in an athymic mouse chronically infected with pnuemonia virus of mice (MPnV)

Hepatitis and syncytia in the liver of a SCID mouse. Note obvious syncytia in this liver due to absence of immune response, compared to liver of an infected immunocompetent mouse

Proliferative colitis in an athymic mouse chronically infected with enterotropic MHV

Small intestine of neonatal mouse infected with enterotropic MHV. Villi are markedly attenuated and there are prominent syncytia at the tips of the villi

Posterior paralysis in a mouse natrual infected with TMEV