Bernard Roizman, ScD, the world’s leading expert on herpes simplex virus (HSV) and Joseph Regenstein Distinguished Service Professor Emeritus of Microbiology and Molecular Genetics and Cell Biology at The University of Chicago, died on April 13, 2026, at the age of 96.
Over a career spanning seven decades, Roizman reshaped the field of virology through his work on HSV, a common, lifelong infection responsible for a range of human diseases. He mapped the virus’s genome, defined how it infects host cells, and developed DNA-based techniques that revealed the roles of specific viral genes in infection and replication.
His work laid the foundation for efforts to develop vaccines against HSV, as well as gene therapies and anti-cancer treatments that use modified forms of the virus. Over the course of his career, he authored more than 650 peer-reviewed publications, a body of work that both shaped and reflected the evolution of modern virology.
More than his discoveries, Roizman was renowned for his approach to science itself. He viewed it “as an opportunity to discover the designs in the mosaics of life,” pursuing questions that revealed overarching themes and underlying patterns as opposed to filling in the details.
“Bernard was not only a towering figure in microbiology and virology, but he was also a devoted champion of the University of Chicago, where his passion for discovery and mentorship shaped generations of scientists,” said Shabaana Khader, PhD, the Betty and Bernard Roizman Professor and Chair of Microbiology at UChicago. “As the holder of the endowed Betty and Bernard Roizman Chair, I am deeply honored to carry forward his legacy of excellence and intellectual courage. He will be deeply missed by all who had the honor of knowing him.”
‘My second love at first sight’
Roizman was born in Romania in 1929. His early life was shaped by the upheaval of World War II, including years of displacement, deprivation, and survival as a refugee as his family fled advancing armies across Eastern Europe. This eventually brought his family to the United States in 1947, where they settled in Philadelphia and he enrolled at Temple University.
Science was not his first calling. “The truth is that as I was growing up I wanted to be a writer,” he wrote in a 2015 autobiographical essay. “My aspirations came to an end when, in order to speed up my graduation from college, I took courses in microbiology. It was my second love at first sight—that of my wife preceded it.”
Roizman married Betty in 1950 and remained deeply devoted to her throughout their 70-year marriage. He took care to ensure that others recognized her warmth and gift for conversation, often directing attention toward her rather than himself.
He earned both his bachelor’s and master’s degrees from Temple before attending the Johns Hopkins School of Public Health, where he received his Doctor of Science (ScD) in 1956. After serving on the faculty at Johns Hopkins University, he joined The University of Chicago in 1965 as an Associate Professor of Microbiology. Roizman spent the next 52 years at UChicago, where he was dedicated to scientific discovery and mentoring the next generation of scientists.
The birth of molecular epidemiology
In the late 1950s, Roizman pioneered methods for purifying HSV DNA and describing its unique structure. Among his most consequential discoveries was that HSV gene sequences vary among unrelated individuals but are identical among related individuals infected with the virus. These “genetic fingerprints” enabled the tracing of viral transmission from person to person, giving rise to “molecular epidemiology.”
Using this approach, Roizman demonstrated that nurses in hospital maternity wards were inadvertently transmitting HSV between infants by failing to wash their hands between patients. His findings led directly to changes in hospital practices and a dramatic reduction in neonatal HSV infections.
Roizman later used early DNA editing techniques to manipulate the HSV genome, identifying the functions of many of its 84 genes, particularly those essential for viral replication. Among these was an enzyme that became a key target for antiviral drug development.
He also discovered ways to harness HSV’s biology for therapeutic purposes. He engineered forms of the virus that lack its ability to damage the central nervous system but retain the capacity to selectively infect and destroy cancer cells. He further demonstrated that modified HSV could serve as a vector for delivering and expressing foreign genes, advancing the development of gene therapy.
A legacy of teaching
Roizman prioritized mentorship, and his influence extended far beyond the laboratory. Over his career, he trained generations of scientists who went on to establish research programs across the United States, Europe, and Asia, extending his impact throughout the global scientific community.
Beginning with his 60th birthday and continuing every five years thereafter, his former students and postdoctoral fellows returned to UChicago for scientific symposia to celebrate his continuing contributions to science, a testament to the lasting impact he had on their lives and careers.
Those who trained with Roizman frequently recalled acts of generosity that extended well beyond science—support offered quietly and without expectation of acknowledgment. He often said that the true measure of his work was the young scientists he mentored and shaped. “What lasts are not the scientific reports, but rather the generations of scientists whose education I may have influenced,” he said.
In his later years, he took particular pleasure in visits from former trainees and colleagues, and in the conversations about science that continued long after his formal career had ended. He retired from the University of Chicago in 2017 but remained active in teaching and mentoring students in virology.
In 2021, the Roizmans endowed the Bernard and Betty Roizman Professorship at the University of Chicago, an enduring commitment to future generations of scientists in the field he helped define. Khader is the first faculty member to hold the distinction.
Roizman was elected to numerous prestigious scientific organizations, including the National Academy of Sciences (1979), the American Academy of Arts and Sciences (1991), the American Academy of Microbiology (1992), the National Academy of Medicine (2001), and a Fellow of the American Association for the Advancement of Science (2004). He was also a foreign member of the Chinese Academy of Engineering (Medicine) and an honorary member of the Hungarian Academy of Sciences.
While Roizman’s contributions to science were extensive and profound, they reflect only part of his legacy. Those who knew him experienced a man of unwavering integrity, humility, and quiet generosity—someone deeply attentive to others and committed to elevating the people around him. His influence extended far beyond his scientific achievements, leaving a lasting imprint on the lives of those he encountered and on the broader human community.
