From obstacle to lynchpin: the evolution of the role of bacteriophage lysogeny in defining and understanding viruses

Abstract

The phenomenon of bacteriophage lysogeny has played a vital role in understanding the nature of viruses more generally. Discovered in 1920, the phenomenon was first wielded by its discoverers as a challenge to the idea that bacteriophages might be autonomous infectious agents of exogenous origin, namely viruses. But by the 1950s, lysogeny had come to be understood as a key mechanism through which some bacteriophages interacted with their bacterial hosts. In this paper we consider the history of the status of bacteriophage lysogeny from obstacle to lynchpin in conceiving of viruses, paying particular attention to the contributions of Eugène and Élisabeth Wollman, Macfarlane Burnet and André Lwoff in effecting this transition. As Lwoff is often acknowledged to be the author of the ‘modern’ virus concept, this paper also retraces the precise experimental, theoretical and technical pathways that led him and his collaborators from their studies of lysogeny to the construction of the said concept. We discuss Lwoff's virus concept and the widening impact of his ideas, with special consideration of how lysogeny helped revolutionise the understanding of virus–host-cell relationships in tumour viruses.