Howard Martin Temin

Howard Martin Temin (December 10, 1934 – February 9, 1994) was an American virologist renowned for discovering reverse transcriptase, the enzyme that enables RNA viruses to synthesize DNA from their RNA genome, thereby challenging the prevailing central dogma of molecular biology that genetic information flows unidirectionally from DNA to RNA. Born in Philadelphia to a Jewish family, Temin earned his bachelor's degree from Swarthmore College in 1955 and his Ph.D. from the California Institute of Technology in 1961 under Renato Dulbecco, focusing on animal virology. He joined the University of Wisconsin–Madison's McArdle Laboratory for Cancer Research in 1960, where he spent his career studying RNA tumor viruses, proposing the "provirus" hypothesis in 1964 that posited a DNA intermediate in viral replication.

Temin's seminal 1970 experiments, independently corroborated by David Baltimore, isolated reverse transcriptase from Rous sarcoma virus, demonstrating RNA-directed DNA polymerase activity and confirming that viral RNA could be transcribed into DNA provirus integrated into host genomes. This breakthrough, shared with Dulbecco and Baltimore, earned the 1975 Nobel Prize in Physiology or Medicine for elucidating tumor virus-host genetic interactions, profoundly influencing retrovirology, oncology, and later AIDS research by revealing mechanisms of viruses like HIV. Temin's rigorous, hypothesis-driven approach persisted amid initial skepticism, as he refined techniques to overcome experimental anomalies, underscoring the enzyme's role in viral oncogenesis and genetic transposition. He also received the National Medal of Science in 1983 for RNA-directed DNA synthesis. Temin died of lung cancer in Madison at age 59, leaving a legacy of mentoring and advancing cancer virology.