On Tuesday January 13, 2026 MCB faculty member Peter Duesberg, a pioneering retrovirologist, public controversialist, and long-time member of the Berkeley community, passed away peacefully after a five-year struggle with stroke-induced aphasia.
Peter grew up in Germany, received a Ph.D. in chemistry from the University of Frankfurt, and then came to Berkeley in 1964 to pursue postdoctoral work in the Virus Laboratory. He was subsequently appointed to a faculty position in the former Department of Molecular Biology, and, following the reorganization of the biological sciences at Berkeley, became a Professor in the Division of Biochemistry and Molecular Biology within the Department of Molecular and Cell Biology, a position that he held until his retirement. Over the course of his career, he trained many graduate students and postdoctoral fellows, many of whom went on to successful scientific careers, including (among others) Karen Beemon, Pamela Mellon, Klaus Bister, Lu-Hai Wang, Michael Lai, Wen-Hwa Lee, and Samuel Pfaff.
Peter's most significant scientific contributions were to our understanding of the retroviral genome, in particular in the discovery of retroviral transforming genes or "viral oncogenes." He initially characterized the genome of Rous sarcoma virus as a large single stranded RNA that could be dissociated into two smaller subunits. Then, in a collaboration with Peter Vogt, he was able to show that the Rous sarcoma virus genome contained a segment that was absent in the transformation-defective mutants that Vogt had previously isolated; this was the key experiment that identified a transforming region, subsequently termed v-src, in the Rous sarcoma virus genome. This finding led a few years later to the discovery, by Bishop, Varmus, and their colleagues, of a cellular homolog of v-src, termed c-src, in the normal cellular genome; the cellular c-src gene presumably served as a progenitor of the viral gene. Using the oligonucleotide fingerprinting technique developed by Fred Sanger, Peter was able to map the position of the v-src gene and other viral genes within the Rous sarcoma virus genome. He used similar approaches to identify other transforming genes in the genomes of other avian retroviruses; these transforming genes also proved to be derived from cellular homologs. These cellular homologs of retroviral transforming genes are now referred to as "proto-oncogenes," "cellular oncogenes," or simply "oncogenes," and alterations in the structure or expression of these genes are widespread in human cancer.
For this and other work on avian retroviruses Peter received a number of awards, including election to the National Academy of Sciences in 1986, and an Outstanding Investigator Award from the National Institutes of Health from 1985 to 1992.
In his later years Peter enjoyed being a maverick and the center of controversy. Notably, despite his role in the discovery of oncogenes, he argued that aneuploidy, an alteration in chromosome number, is solely responsible for cancer development. The current scientific consensus is that both mutations in oncogenes and alterations in chromosome number contribute to carcinogenesis. In a second controversy, Peter argued that HIV does not play a causal role in the development of AIDS, and that anti-retroviral agents are at best ineffective in the treatment of the disease, a stance that was amplified by political leaders to the detriment of public health. In this instance the scientific consensus is that HIV is indeed the primary cause of AIDS, and that the current suite of anti-retroviral agents is very effective in slowing or halting the progression of the disease and its spread in the population.
Away from the public spotlight in which his ideas were contested, Peter was warm and friendly, with a quirky, inventive, and often black sense of humor. He is survived by his wife, Sigrid, their son Max, three daughters by a previous marriage, Suzy, Sybil and Nicola, and grandchildren.
Read more about Duesberg in this New York Times article.