Cover photograph (Copyright © 2001, American Society for Microbiology. All rights reserved.): During the 1918-1919 pandemic, influenza virus was responsible for the death of millions worldwide. Experts suggest we are overdue for a major influenza outbreak in the near future. Geiss and colleagues described a global analysis of host cell gene expression in response to influenza virus infection by using DNA microarrays. While more genes were downregulated, genes involved in protein synthesis, transcription, and cytokine signaling were induced by infection. Unexpectedly, viral attachment alone provides a warning signal to the host cell. Genome-scale analysis of virus-host interactions may provide a much-needed alternative pathway to the discovery of novel antiviral therapies. (See related article in the May 2001 issue: vol. 75, no. 9, p. 4321-4331.)