Innate antiviral defense demonstrates high energetic efficiency in a bony fish

Area of Science:

• * Comparative physiology
• * Infectious disease ecology
• * Vertebrate immunology

Background:

• * Viruses can increase host energetic demands through resistance mechanisms.
• * Oxygen uptake is a reliable indicator of energy consumption in vertebrates.
• * This study investigates the energetic costs of viral resistance and tolerance in sockeye salmon.

Purpose of the Study:

• * To evaluate the energetic costs of mounting resistance to viral infections in sockeye salmon.
• * To determine if the innate antiviral interferon system compromises host homeostasis.
• * To assess if acute stress weakens antiviral defenses.

Main Methods:

• * Sockeye salmon were challenged with virulent infectious salmon anemia virus (IHNV) or a low-virulent reovirus (PRV).
• * Oxygen uptake was measured to assess metabolic rate and energy expenditure.
• * Transcriptomic analysis of interferon-stimulated genes (ISGs) was performed.

Main Results:

• * Resistance to IHNV was associated with a 19% reduction in standard metabolic rate, not an increase.
• * Interferon-stimulated gene transcription correlated with viral load but not respiratory performance.
• * Acute stress did not increase IHNV loads but elevated inflammatory signaling.

Conclusions:

• * Effective viral resistance and tolerance in salmon incur minimal metabolic costs.
• * The innate interferon system does not compromise host homeostasis or respiratory performance.
• * Innate antiviral defenses impose limited energetic costs on vertebrates.