Robin Weiss is Emeritus Professor of Viral Oncology in the Division of Infection & Immunity at University College London (UCL). Weiss is a virologist and cell biologist best known for the discovery of endogenous retroviruses in chickens, and that CD4 is the binding receptor for HIV. Born in 1940 in London, Weiss gained his BSc in 1961 and his PhD in 1969 at UCL. He worked in Kerala, India, in Prague, Czech Republic, and in Seattle and Los Angeles, USA, before taking a post at the Imperial Cancer Research Fund Laboratories, London in 1972. He was Director of Research at the Institute of Cancer Research, London, 1980-1998, returning to UCL in 1999. Until recently he was supported by the Bill & Melinda Gates Foundation to manage a team engaged in the Collaboration on AIDS Vaccine Research. Weiss has been president of the British Association for Cancer Research and president of the Society for General Microbiology. He currently chairs the Scientific Advisory Committee of the International AIDS Vaccine Initiative. Research Interests Weiss studies the properties of the envelope glycoproteins of HIV-1, gp41 and gp120, their interaction with cell surface receptors, CD4 and CCR5, and as the target for neutralizing antibodies. He has exploited single chain natural antibodies elicited in immunized llamas to develop monoclonal antibody fragments that possess potent and broadly neutralizing activity, and which have potential as vaginal microbicides. Weiss has also maintained a long-term interest in cancers caused by infection. In addition to studying the natural history of oncogenic viruses such as human T-cell leukemia virus and Kaposi's sarcoma herpesvirus, he has shown that the causative agent of canine transmissible venereal tumor is the tumor cell itself. This malignant cell clone arose approximately 11,000 years ago and has been continually passed from dog to dog during this time to spread worldwide. It represents the oldest known somatic cell lineage of mammals.