Murine norovirus (MNV)

RNA virus, nonenveloped; Family: Caliciviridae.
 
Prevalence
Common.
 
Diagnosis
Serology or PCR .
 
Disease
No clinical signs are seen in immunocompetent mice and most immunodeficient mice. Mice deficient in STAT1 gene were the first description of the disease. Signs included wasting, diarrhoea and death with lesions of hepatitis, peritonitis, interstitial pneumonia. 
 
Strains
Certain immunodeficient strains eg. STAT1 deficient mice and other interferon signalling pathways and/or interferon receptor deficits. 
 
Screening
Soiled bedding sentinels for at least 8 weeks for antibody titre to rise. 
 
Transmission
Faecal-oral transmission.
 
Duration
Persistent infection. 
 
Durability
Difficult to eradicate from the environment, requires chemical decontamination with detergents and oxidising disinfectants.
 
Significance
Immunological research may be affected because the virus persists in the macrophages. If the research involves certain immunodeficient lines, they may become ill and die with the infection. 
 
Control
Pathogen exclusion. Hysterectomy rederivation and embryo transfer.
 
Reading
  • Infectious Diseases of Mice and Rats National Research Council 1991.
  • Pathology of Laboratory Rodents and Rabbits, 3rd Edn., Dean H Percy & Stephen W Barthold, 2007.
  • University of Missouri, Research Animal Diagnostic Laboratory website, http://www.radil.missouri.edu