The antiviral response to gamma interferon.

Area of Science:

• Immunology
• Virology
• Molecular Biology

Background:

• The interplay between alpha/beta interferon (IFN-alpha/beta) and gamma interferon (IFN-gamma) in antiviral defense is not fully understood.
• Investigating the potential roles of autocrine or double-stranded RNA (dsRNA)-induced IFN-alpha/beta in the IFN-gamma response is crucial for clarifying antiviral mechanisms.

Purpose of the Study:

• To determine the role of IFN-alpha/beta pathways in the IFN-gamma-mediated antiviral response.
• To investigate whether IFN-gamma induces IFN-alpha/beta production or if its response is dependent on autocrine IFN-alpha/beta.
• To examine the effect of IFN-gamma priming on dsRNA-induced responses and associated signaling pathways.

Main Methods:

• Utilized wild-type and mutant human fibrosarcoma cell lines, including U5A cells lacking a functional IFN-alpha/beta receptor.
• Assessed IFN-alpha/beta induction by IFN-gamma and the dependency of the IFN-gamma response on autocrine IFN-alpha/beta.
• Evaluated the enhancement of dsRNA (poly(I)·poly(C)) and encephalomyocarditis virus responses by IFN-gamma pretreatment, analyzing mRNA induction and MAP kinase activation.

Main Results:

• IFN-gamma did not induce detectable IFN-alpha/beta levels, and the IFN-gamma response was independent of autocrine IFN-alpha/beta.
• IFN-gamma pretreatment significantly enhanced responses to dsRNA and virus, including dsRNA-inducible mRNA induction (e.g., IFN-beta mRNA) and p38 MAP kinase activation.
• IFN-gamma priming of dsRNA responses showed biphasic kinetics, was JAK1-dependent, and modulated by p38, PI3K, and ERK1/2 pathways.

Conclusions:

• IFN-alpha/beta pathways play no significant role in the primary IFN-gamma antiviral response in the studied cell-virus systems.
• IFN-gamma priming of dsRNA responses is a key mechanism that enhances antiviral defense.
• The observed IFN-gamma priming of dsRNA responses is likely important for combating viral infections in vivo.