SPECIFIC ANTIBODIES TO THERMALLY DENATURED DEOXYRIBONUCLEIC ACID OF PHAGE T4

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Abstract
In this study, a reaction between thermally denatured DNA and antibody present in antisera of rabbits immunized with ruptured T4 phage was demonstrated. Evidence that the antigenicity resides in the DNA molecule is manifold. The protein content of the DNA preparation is too low to account for the observed fixation of C. In infected cells, the times of synthesis of DNA and of the immunologically reactive substance coincide. Pancreatic DNase and Escherichia coli phosphodiesterase, enzymes that hydrolyse DNA in entirely different ways, destroy the antigenicity in parallel with their known enzymatic action. The serological reactivity is low with native DNA and with DNA that has been first denatured and then restored by heating at 55[degree]C. The effects of varied temperature, concentration, ionic strength and pH all indicate that serological reactivity manifests itself when the DNA strands are separated and disappears when the strands recombine. Several observations suggest that the repeat unit responsible for the serological specificity is gluco-sylated 5-hydroxymethylcytosine. The antibody found in T4 antiserum cross reacts with DNA from T2 and T6, but not with E. coli DNA or with DNA from calf thymus. Among derivatives of T2, only one with a high glucose content yields a DNA serologically equivalent to that of T4. Glucose itself does not complete in the reaction with DNA, but 5-hydroxymethylcytosine does to some extent. The possibility that DNA contains other determinants of serological specificity is not, of course, excluded by these observations. Antibodies to thermally denatured DNA have also been found in anti-T2 and anti-T6 sera. Immunization with non-glucosylated DNAs has not yet been successful.