AFIP SYSTEMIC PATHOLOGY

JPC SYSTEMIC PATHOLOGY

NERVOUS SYSTEM

April 2017

N-V18 (NP)

 

Signalment (JPC #0875478):  A mouse

 

HISTORY:  This mouse was experimentally infected with an infectious agent; the animal exhibited signs of drowsiness, emaciation, and roughened hair coat.

 

HISTOPATHOLOGIC DESCRIPTION:  Cerebrum, cerebellum, and brainstem:  Multifocally infiltrating the meninges are high numbers of lymphocytes, plasma cells, and rare neutrophils.  A similar infiltrate multifocally extends from the meninges into the neuropil and surrounds vessels (perivascular cuffing), expanding the Virchow-Robin space. The submeningeal neuropil diffusely contains increased clear space and occasional eosinophilic amorphous substance (edema) and multifocal hemorrhage.  Low numbers of lymphocytes infiltrate the attachments of the choroid.

 

MORPHOLOGIC DIAGNOSIS:  Cerebrum:  Meningitis and ventriculitis, lymphoplasmacytic, diffuse, moderate, with perivascular cuffing, and mild encephalitis and choroiditis, mouse, breed unspecified, murine.

 

ETIOLOGIC DIAGNOSIS:  Arenaviral choriomeningitis

 

CAUSE:  Lymphocytic choriomeningitis virus (LCMV‑ Arenavirus)

 

CONDITION:  Lymphocytic choriomeningitis

 

GENERAL DISCUSSION:

·       Named for the ability to produce lymphocytic choriomeningitis in intracerebrally inoculated mice and monkeys; this is not a feature of natural infection

·       A zoonotic RNA virus with a wide host range including rodents and primates;  the mouse is the natural host but the hamster and mouse are the primary sources for human infection

 

PATHOGENESIS:

·       Transmission may occur by exposure to saliva or urine

·       Dependent on virus strain, mouse age, genotype, and route of infection

·       In utero infection is major means of transmission in the mouse

·       Neonatal mice develop immunotolerance and become persistently infected

·       Eventually tolerance breaks down with development of immune mediated disease and lymphocytic infiltrates in a variety of tissue

·       Persistently infected mice serve as source of infection for the colony

·       Natural infection of immunocompetent adults result in short term, acute infection from which they recover and sero-convert

·       Definite diagnosis cannot be based on pathology

 

 

TYPICAL CLINICAL FINDINGS:

·       Runting of infant mice and chronic wasting in older mice

 

TYPICAL GROSS FINDINGS:

·       Nonspecific signs including conjunctivitis, ascites, splenomegaly and hepatic lipidosis

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

·       In persistently infected mice, vasculitis and lymphocytic infiltrates in a variety of tissues

·       Immune mediated glomerulonephritis

·       Acute disease results from experimental inoculation and can produce nonsuppurative choriomeningitis, necrotizing hepatitis, and lymphoid depletion

 

ULTRASTRUCTURAL FINDINGS:

·       Cellular ribosomes within virions resemble grains of sand ("arena" = sand)

 

ADDITIONAL DIAGNOSTIC TESTS: 

·       Serology must be applied to a large sample size in order to detect immunotolerant mice within a colony

·       Sentinels housed with persistently infected mice will seroconvert

·       Intracerebral inoculation of adult mice (LCMV is the only virus of mice currently recognized that will kill adults, but not neonates, when inoculated intracerebrally)

 

DIFFERENTIAL DIAGNOSIS:

·       Glomerulonephritis associated with other persistent viral infections or immune disorders

 

COMPARATIVE PATHOLOGY:

·       Callitrichidae - Highly fatal disease of New World primates in the Callitrichidae family, especially golden lion tamarins with development of necrotizing hepatitis

 

References:

  1. Fox JG, Cohen BJ, Loew FM. Laboratory Animal Medicine. San Diego, CA: Academic Press, Inc.; 1984:66-69,183-184,1066-1068,1160-1161.
  2. MacLachlan NJ, Dubovi EJ. Fenner’s Veterinary Virology. 4th ed. Oxford, UK: Elsevier; 2011: 388-390.
  3. Montali RJ, Connolly BM, Armstrong DL, Scanga CA, Holmes KV. Pathology and immunohistochemistry of callitrichid hepatitis, an emerging disease of captive New World primates caused by lymphocytic choriomeningitis virus.  Am J Pathol 1995;147:1441-1449.
  4. Percy DH, Barthold SW, Griffey SM. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Blackwell Publishing Professional; 2016:23-25,178.
  5. Teijaro JR, Ng C, Lee AM, et al. Persistent LCMV infection is controlled by blockade of type I interferon signaling. Science. 2013;340(6129):207-211.
  6. Wilson EB, Yamada DH, Elsaesser H, et al. Blockade of chronic type I interferon signaling to control persistent LCMV infection. Science. 2013;340(6129):202-207.

 

 


Click the slide to view.



Click on image for diagnostic series.



Back | Home | Contact Us | Links | Help |