New strain of mouse hepatitis virus as the cause of lethal enteritis in infant mice
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Abstract:
A new strain of mouse hepatitis virus (MHV) was isolated from pooled gut suspensions from an epizootic of lethal enteritis in newborn mice. Negative-contrast electron microscopy showed an abundance of coronavirus particles in the intestinal contents and intestinal epithelium of moribund mice. We found no other virus in the epizootic. Dams seroconverted to MHV polyvalent antigen and to the agent isolated, but did not develop antibodies to other known mouse pathogens. Virus propagated in NCTC-1469 tissue culture produced enteric disease in suckling mice but not fatal diarrhea; the dams of these mice also developed antibodies to MHV and to the isolates. By complement fixation, single radial hemolysis, and quantal neutralization tests, we found the isolates antigenically most closely related to MHV-S, unilaterally related to MHV-JHM, and more distantly related to MHV-1, MHV-3, MHV-A59, and human coronavirus OC-43. We also studied cross-reactions among the murine and human coronaviruses in detail. Tissues of infected newborn mice were examined by light microscopy, thin-section electron microscopy, and frozen-section indirect immunofluorescence, revealing that viral antigen, virus particles, and pathological changes were limited to the intestinal tract. We have designated our isolates as MHV-S/CDC.
Insights
A novel mouse hepatitis virus (MHV) strain, MHV-S/CDC, was identified from lethal enteritis in newborn mice. This coronavirus exclusively affected the intestinal tract, with no other pathogens detected.
Area of Science:
- Virology
- Infectious Diseases
- Animal Pathology
Background:
- Mouse hepatitis virus (MHV) is a significant pathogen in laboratory mice, causing various diseases.
- Enteritis in newborn mice can lead to significant mortality and morbidity in research settings.
Purpose of the Study:
- To isolate and characterize a novel MHV strain responsible for an epizootic of lethal enteritis in newborn mice.
- To determine the antigenic relationship of the new isolate to other known MHV strains and human coronaviruses.
Main Methods:
- Isolation of the virus from gut suspensions and propagation in cell culture.
- Negative-contrast electron microscopy to visualize viral particles.
- Serological assays including complement fixation, single radial hemolysis, and neutralization tests.
- Histopathological examination of infected tissues using light and electron microscopy, and immunofluorescence.
Main Results:
- A new MHV strain, designated MHV-S/CDC, was isolated from mice with lethal enteritis.
- The virus was shown to cause enteric disease in suckling mice.
- Antigenic analysis revealed the isolate is most closely related to MHV-S and unilaterally related to MHV-JHM.
- Pathological changes and viral presence were confined to the intestinal tract.
Conclusions:
- MHV-S/CDC is a distinct strain of mouse hepatitis virus causing severe enteric disease.
- The findings contribute to understanding MHV diversity and its impact on mouse models.
- Detailed antigenic characterization aids in differentiating MHV strains and understanding cross-reactivity.