174] Preparation and assay of nucleic acids as antigens

Abstract

DNA-specific antibodies may be produced in individuals with lupus erythematosus (LE) and in rabbits injected with a lysate of T4 bacteriophage. Purine and pyrimidine bases are haptens when chemically coupled to bovine serum albumin or synthetic polypeptides. Rabbits injected with such protein-hapten conjugates produced purine and pyrimidine-specifie antibodies capable of reacting with DNA and RNA. Bovine serum albumin is extensively used as a carrier protein for simple haptens; methylated bovine serum albumin (MBSA)—a basic protein—is tested as a carrier for DNA. The stability of complexes formed between nucleic acids and MBSA depends upon the concentration and type of salt in the medium, as well as the pH. Owing to the greater ease in dissolving MBSA in water than in 0.15 M NaC1, MBSA is added to the hapten as a 1% aqueous solution. A relatively small volume is required because of the greater concentration of MBSA so that the concentration of salt in the final solution is essentially 0.15 M. Protein-nucleic acid conjugates are formed by mixing the solutions of nucleic acid and MBSA at room temperature in amounts such that the weight ratio of nucleic acid to MBSA is one. The chapter also discusses the preparation of MBSA, the preparation of antiserum, and assay of antiserum.