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Factors involved in the age-dependent resistance of mice infected with low-virulence mouse hepatitis virus
Abstract:
Four-week-old weanling mice survived, whereas 1-week-old suckling mice died, after intraperitoneal inoculation of mouse hepatitis virus, MHV-S strain. The factors involved in this difference in susceptibility were studied. After virus inoculation, differences in virus growth in the liver and spleen were observed, which correlated with the susceptibility of animals to the virus. Interferon, detected at an early stage of infection, was considerably lower in suckling mice than in weanling mice. Titers of MHV-S in peritoneal cells from infected animals were at least 100 times greater in suckling than in weanling mice, and a similar, but less prominent difference in virus growth was also found in the corresponding cultured macrophages. After transfer of peritoneal cells from weanling to suckling mice, a decrease in mortality of infected suckling mice was observed. These results suggest that both interferon and macrophages may be important in the age-dependent resistance of mice to MHV-S infection.
Insights
Younger mice infected with mouse hepatitis virus (MHV-S) are more susceptible due to lower interferon and impaired macrophage function. This age-dependent resistance highlights the roles of innate immunity in MHV-S infection outcomes.
Area of Science:
- Virology
- Immunology
- Infectious Diseases
Background:
- Mouse hepatitis virus (MHV-S) exhibits age-dependent pathogenicity in mice.
- Susceptibility differences between suckling and weanling mice require investigation.
Purpose of the Study:
- To elucidate the factors contributing to age-related resistance against MHV-S infection.
- To assess the roles of interferon and macrophages in differential susceptibility.
Main Methods:
- Intraperitoneal inoculation of MHV-S in suckling and weanling mice.
- Measurement of virus titers in organs and peritoneal cells.
- Assessment of interferon levels and macrophage function.
- Peritoneal cell transfer experiments.
Main Results:
- Suckling mice exhibited higher MHV-S titers in the liver and spleen compared to weanling mice.
- Lower interferon levels were detected in suckling mice during early infection.
- MHV-S titers were significantly higher in peritoneal cells and macrophages of suckling mice.
- Transfer of weanling peritoneal cells reduced mortality in infected suckling mice.
Conclusions:
- Interferon production and macrophage antiviral activity are crucial for age-dependent resistance to MHV-S.
- These innate immune components play a significant role in determining the outcome of MHV-S infection based on age.