Immunospecific binding of capped mRNA of reovirus by an antibody to a cap structures; m7G(5')pppGm

Antibodies specific for nucleic acids and applications in genomic detection and clinical diagnostics

Detection of nucleic acids using antibodies is uncommon. This is in part because nucleic acids are poor immunogens and it is difficult to elicit antibodies having high affinity to each type of nucleic acid while lacking cross-reactivity to others. We describe the origins and applications of a variety of anti-nucleic acid antibodies, including ones reacting with modified nucleosides and nucleotides, single-stranded DNA, double-stranded DNA, RNA, DNA:RNA hybrids, locked-nucleic acids or peptide nucleic acid:nucleic acid hybrids. Carefully selected antibodies can be excellent reagents for detecting bacteria, viruses, small RNAs, microRNAs, R-loops, cancer cells, stem cells, apoptotic cells and so on. The detection may be sensitive, simple, rapid, specific, reproducible, quantitative and cost-effective. Current microarray and diagnostic methods that depend on cDNA or cRNA can be replaced by using antibody detection of nucleic acids. Therefore, development should be encouraged to explore new utilities and create a robust arsenal of new anti-nucleic acid antibodies.

Antibodies specific for branched ribonucleic acids

A chemically synthesized branched tetranucleotide, G3'p5'A [2'p5'G]3'p5'C corresponding to the consensus sequence at the branch point in introns undergoing RNA splicing, was used as a hapten to elicit antibranch antibodies. Binding assays with 32P-labeled hapten and unlabeled structurally related haptens indicated that the antibodies are highly specific for the branch structure and have some specificity for the A2'p5'G sequence at the branch point, but have essentially none for a variety of other 2'p5' or 3'p5' dinucleotides or for the linear trinucleotide G3'p5'A3'p5'C. Purification of these antibodies by binding to A2'p5'G covalently linked to Sepharose followed by covalent attachment of the purified antibodies to protein A-Sepharose has provided an adsorbent that immunospecifically retains branched oligonucleotides as well as branched introns released from RNAs during in vitro splicing.

Detection of human autoantibodies specific for 5'-m7GMP and m7G(5')ppp(5')N

An enzyme-linked immunosorbent assay was utilized for the detection of spontaneously occurring antibodies with apparent specificities for m7G, 5'-m7GMP, and m7G(5')ppp(5')C. From the sera of 50 patients containing anti-nuclear antibodies, 48 (96%) possessed antibodies which bound to one or more immobilized nucleoside-BSA antigens (A-, G-, C-, U-, and T-BSA). Additionally, 8 (16%) of these sera contained immunoglobulins that reacted with m7G-BSA antigen. In these latter sera, soluble competitors such as m7G, 5'm7GMP, and m7G(5')ppp(5')C (but not 5'-AMP, -GMP, -CMP, -UMP, and -TMP or m1G and m22G) effectively inhibited antibody-binding to immobilized m7G-BSA. These results indicate the existence of spontaneously occurring anti-m7G antibodies in autoimmune diseases which are distinct from anti-G antibody populations.