Neonatal influenza virus infection affects myelination in influenza-recovered mouse brain

Area of Science:

• Neuroscience
• Virology
• Immunology

Background:

• Influenza virus infection is a zoonotic disease with significant global socioeconomic impact.
• Central nervous system (CNS) sequelae can result from influenza virus brain infections, particularly in vulnerable children.
• Previous research indicated functional changes in hippocampal neurons following neonatal influenza infection.

Purpose of the Study:

• To investigate the impact of neonatal influenza infection on brain myelination properties in recovered mice.
• To determine if changes in myelination contribute to neural dysfunction after influenza infection.
• To explore the molecular mechanisms underlying altered myelination in response to influenza.

Main Methods:

• Neonatal mice were infected with influenza virus on postnatal day 5 and tissues were collected 21 days post-infection.
• Myelin basic protein (MBP) expression was analyzed using real-time PCR, Western blot, and immunohistochemistry.
• Transmission electron microscopy was used to assess myelination via G-ratio calculation.
• Oligodendrocyte-enriched primary brain cell cultures were used to study the effect of cytokines on MBP expression.

Main Results:

• Increased mRNA and protein expression of MBP was observed in the hippocampus and cerebellum of recovered mice.
• Immunohistochemistry revealed an increased MBP-staining signal in the brains of recovered mice.
• Electron microscopy showed an increased G-ratio in both the hippocampus and cerebellum, indicating altered myelination.
• In vitro studies suggested that proinflammatory cytokines may induce MBP upregulation.

Conclusions:

• Neonatal influenza infection alters brain myelination properties in mice.
• Increased MBP expression may represent a compensatory mechanism related to hypomyelination following influenza infection.
• These myelination changes could underlie the observed neural dysfunction in influenza-recovered mice.