The viruses were made harmless and then genetically engineered to carry genetic material called RNA that would interfere with the faulty RNA produced by the mutant human SOD1 genes in the mice.

病毒通过缺失使之变得无害，再通过基因操作携带遗传物质RNA，该RNA能干扰老鼠身上被植入的人SOD1突变基因所产生的异化RNA。