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Protection of mice against mouse hepatitis virus by Corynebacterium parvum
Abstract:
C57BL/6 mice that are highly susceptible to infection with mouse hepatitis virus type 3 were protected against intraperitoneal viral infection by simultaneous intraperitoneal injection of Corynebacterium parvum. No protection was observed when C. parvum was given intravenously or when it was injected intraperitoneally 3 days before viral infection. Protective effects were, however, consistently found when C. parvum was given 2 h before or 2 h after viral infection. Activity was seen only against 10 50% lethal doses and not against 100 50% lethal doses. C. parvum also caused a significant decrease of virus type 3. These data suggest a direct effect of C. parvum on virus-susceptible cells. Injection of C. parvum in mice caused activation of natural killer (NK) cells and of interferon production. However, these two effects were equally demonstrable at high and low doses of C. parvum, whereas protection against mouse hepatitis virus type 3 was not demonstrable at low doses of C. parvum. Thus, antiviral protection may be dissociated from activation of NK cells and induction of interferon.
Insights
Corynebacterium parvum protects mice against mouse hepatitis virus type 3 when injected simultaneously with the virus. This antiviral protection is dose-dependent and may be independent of natural killer cell activation.
Area of Science:
- Immunology
- Virology
- Microbiology
Background:
- Mouse hepatitis virus type 3 (MHV-3) causes severe infections in C57BL/6 mice.
- Understanding host-pathogen interactions and potential therapeutic interventions is crucial.
Purpose of the Study:
- To investigate the protective effects of Corynebacterium parvum (C. parvum) against MHV-3 infection in mice.
- To explore the relationship between C. parvum administration timing, dosage, and antiviral efficacy.
Main Methods:
- C57BL/6 mice were infected intraperitoneally with MHV-3.
- C. parvum was administered via intraperitoneal or intravenous routes at various time points relative to viral infection.
- Viral load and survival rates were assessed.
- Natural killer (NK) cell activity and interferon production were measured.
Main Results:
- Simultaneous intraperitoneal injection of C. parvum protected mice against MHV-3 infection.
- Protection was observed when C. parvum was given up to 2 hours before or after viral challenge.
- Efficacy was dose-dependent, with activity seen only against lower lethal doses of MHV-3.
- C. parvum treatment significantly reduced virus titers.
- While C. parvum activated NK cells and interferon production, these effects were not directly correlated with the dose-dependent antiviral protection.
Conclusions:
- Corynebacterium parvum demonstrates significant antiviral activity against mouse hepatitis virus type 3.
- The timing of C. parvum administration is critical for protection.
- Antiviral protection conferred by C. parvum may be dissociated from NK cell activation and interferon induction, suggesting alternative mechanisms of action.