Structural features of double-stranded polyribonucleotides required for immunological specificity and interferon...

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• Polyribonucleotides like poly(adenylic acid)-poly(uridylic acid) and poly(inosinic acid)-poly(cytidylic acid) are known to induce interferon.
• Understanding the structural basis of antibody recognition of these nucleic acids is crucial for immunological studies.

Purpose of the Study:

• To investigate conformational variations in double-helical polyribonucleotide analogs.
• To correlate structural changes with serological reactivity and interferon-inducing ability.

Main Methods:

• Quantitative microcomplement fixation assays using purified antibody to poly(adenylic acid)-poly(uridylic acid).
• Evaluation of various double-helical polyribonucleotide analogs with modifications at the furanose 2'-position and bases.

Main Results:

• Modification at the furanose 2'-position drastically reduced antibody binding.
• Base modifications caused smaller changes in serological reactivity, without complete loss.
• Structural changes affecting antibody recognition also significantly altered interferon induction.

Conclusions:

• The furanose structure and overall helix conformation are critical for antigenic determinant formation.
• Both nucleic acid strands' backbones contribute to a single antigenic site.
• Base modifications can influence the steric interactions between backbones, impacting antigenicity and biological activity.