Douglas Steinberg | May 1, 2000 | 9 min read
Editor's Note: This is the second of two articles on the difficulties of proving that a virus contributes to a disease. The first article, on mouse mammary tumor virus and human breast cancer, appeared in the April 17 issue of The Scientist.1 Donald R. Carrigan and Konstance K. Knox Someone once said that if you want to ruin your reputation, go into MS [multiple sclerosis] research, quips Jacqueline E. Friedman, a senior research associate at Rockefeller University. But Friedman, who deals wit