Differential Response Following Infection of Mouse CNS with Virulent and Attenuated Vaccinia Virus Strains

Area of Science:

• Neurovirology
• Immunology
• Pathology

Background:

• Central nervous system (CNS) viral infections cause diverse pathologies, often linked to Orthopodox viruses like vaccinia virus.
• Limited understanding of viral replication and clearance mechanisms hinders risk assessment for vaccine adverse reactions.
• Existing data lacks mechanistic insights into viral CNS disease progression and outcome prediction.

Purpose of the Study:

• To investigate the mechanisms of viral pathogenesis and clearance in the CNS.
• To compare the effects of neurovirulent and attenuated viral strains on host responses.
• To identify biomarkers associated with CNS viral infection outcomes.

Main Methods:

• Utilized a mouse model of viral CNS infection, comparing neurovirulent and attenuated Orthopodox virus strains.
• Monitored viral load, morbidity, mortality, tissue integrity, immune responses (innate and adaptive), and blood-brain barrier function.
• Performed whole-brain RNA sequencing at multiple time points to analyze host gene expression.

Main Results:

• Neurovirulent strains induced host immune silencing and tissue damage pathways.
• Attenuated strains elicited rapid innate and adaptive immune responses, leading to viral clearance and recovery.
• Correlations were established between viral load, host response, tissue integrity, and disease outcome.

Conclusions:

• Host immune response dynamics dictate the outcome of viral CNS infections.
• Neurovirulence is characterized by immune evasion and subsequent tissue damage.
• Attenuated viral infections promote protective immunity and viral clearance, offering a model for recovery mechanisms.