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Murine influenza virus encephalomyelitis. III. Effect of defective interfering virus particles
Abstract:
Defective interfering influenza virus particles lessened the yield of infective virus recovered from brain after intracerebral challange of 3-week old mice, but failed to affect the appearance of disease or lethality. In 7-week old mice, the presence of defective interfering influenza virus particles reduced both lethality and virus yield. Viral inocula containing significant numbers of defective particles appeared to diminish later inflammatory changes, nerve cell degeneration and the appearance of viral antigen in deeper cerebral regions. The protective effect exerted by defective virus particles does not appear related to interferon production in brain.
Insights
Defective interfering influenza virus particles reduced disease severity and lethality in older mice but not younger ones. This protective effect in the brain did not involve interferon production.
Area of Science:
- Virology
- Neuroscience
- Immunology
Background:
- Influenza virus infections can cause severe neurological complications.
- Defective interfering particles (DIPs) are variants of viruses that require a standard virus for replication.
- The role of DIPs in influenza neuroinvasion and pathogenesis is not fully understood.
Purpose of the Study:
- To investigate the impact of defective interfering influenza virus particles on the outcome of influenza virus infection in the mouse brain.
- To determine if DIPs influence viral replication, disease progression, and neuropathology.
- To explore the potential mechanisms underlying any protective effects of DIPs, such as interferon production.
Main Methods:
- Intracerebral inoculation of mice (3-week-old and 7-week-old) with influenza virus preparations containing varying amounts of defective interfering particles (DIPs).
- Assessment of viral yield in brain tissue.
- Monitoring of clinical signs of disease, lethality, and neuropathological changes (inflammation, neuronal degeneration, viral antigen).
- Measurement of interferon levels in brain tissue.
Main Results:
- In young mice (3 weeks), DIPs reduced infectious virus yield but did not alter disease or lethality.
- In older mice (7 weeks), DIPs decreased both lethality and viral yield.
- DIPs diminished later inflammatory responses, nerve cell damage, and viral antigen presence in deeper brain areas.
- The observed protective effects of DIPs in the brain were not associated with increased interferon production.
Conclusions:
- Defective interfering influenza virus particles exhibit age-dependent protective effects against influenza virus encephalitis in mice.
- DIPs can reduce viral load and neuropathology, particularly in older animals.
- The neuroprotective mechanism of DIPs in this model does not appear to be mediated by brain interferon induction.