Gender differences in viral infection after repeated exercise stress

Area of Science:

• Immunology
• Exercise Physiology
• Virology

Background:

• Fatiguing exercise can compromise the immune system, increasing susceptibility to infections like herpes simplex virus-1 (HSV-1).
• Previous studies indicate male mice are more susceptible to respiratory infections post-exercise, but gender-specific responses to strenuous exercise and HSV-1 are not well understood.

Purpose of the Study:

• To investigate the impact of gender on susceptibility to HSV-1 respiratory infection following repeated exhaustive exercise.
• To compare the morbidity and mortality rates between male and female mice after exercise stress and viral inoculation.

Main Methods:

• Male and female CD-1 mice were subjected to 3 days of treadmill running until volitional fatigue or assigned to control groups.
• Fifteen minutes post-exercise, mice were intranasally inoculated with a standard dose of HSV-1.
• Morbidity (sickness onset and severity) and mortality were monitored over 21 days.

Main Results:

• Female mice exhibited significantly longer run times to fatigue compared to males.
• Exercise stress led to increased morbidity in both genders (66%), but significantly increased mortality only in males (30%).
• While both genders showed similar initial sickness rates, females demonstrated a greater capacity for recovery.

Conclusions:

• Gender plays a role in the response to exercise-induced immune suppression and subsequent viral infection.
• Female mice, despite similar initial morbidity, are ultimately better protected from mortality compared to males following strenuous exercise and HSV-1 exposure.
• These findings highlight sex-based differences in immune resilience and recovery mechanisms.