Interferon research BC (before cloning).

As we approach the 50th anniversary of the publications describing the discovery of interferon, it is appropriate to look back at some of the trials and tribulations marking the early days of interferon research. This brief chapter, drawn largely from the author's own experiences, relates how progress was achieved in some key areas of interferon research in the 1960s and 1970s despite the lack of analytical tools that had become available only after the successful cloning of interferon genes. One of the topics discussed concerns the evolution of the idea that interferon synthesis is controlled both at transcriptional and posttranscriptional levels. I also recount some of the early work that led to the identification of IFN-alpha and IFN-beta as the two major type I interferon species.