Interferon inducing activity of polyinosinic acid

Area of Science:

• Immunology
• Virology
• Biochemistry

Background:

• Polyriboinosinic acid (poly(I)) is typically considered inactive as an interferon inducer.
• Interferon induction is a critical component of the innate immune response against viral infections.

Purpose of the Study:

• To investigate the interferon-inducing potential of authentic polyriboinosinic acid (poly(I)) preparations.
• To compare the efficacy and stability of poly(I) with polyriboinosinic acid:polyribocytidylic acid (poly(I)·poly(C)) in various biological systems.

Main Methods:

• Assaying interferon induction in human diploid fibroblasts, rabbit kidney cell cultures, and intact rabbits.
• Evaluating interferon induction in interferon-treated and DEAE-dextran-treated mouse L cells.
• Assessing the susceptibility of poly(I) and poly(I)·poly(C) to degradation by nucleases (TI ribonuclease, pancreatic ribonuclease, human serum nucleases).

Main Results:

• Several poly(I) preparations demonstrated significant interferon-inducing activity, contrary to previous assumptions.
• Efficacy varied across cell systems, with poly(I) being nearly as effective as poly(I)·poly(C) in superinduced human fibroblasts but less effective in other systems and in vivo.
• Poly(I) was found to be more susceptible to enzymatic degradation by nucleases compared to poly(I)·poly(C).

Conclusions:

• Authentic poly(I) can function as an interferon inducer, with activity dependent on the biological system.
• The increased susceptibility of poly(I) to degradation may contribute to its variable efficacy but could also enhance its safety profile for clinical applications due to a limited half-life.