The long term objective of this project is the furtherance of our knowledge of the dsDNA virus life cycle by gaining an understanding of the molecular mechanisms by which these viruses packaging DNA and assembly progeny virions within infected cells. The particular virus chosen for this study, bacteriophage P22, serves as a model for similar processes in less experimentally accessible, human pathogenic virus such as the Herpesviruses and Adenoviruses. This type of virus assembles protein shells first and then inserts the dsDNA chromosomes into those shells. Two bacteriophage P22 proteins appear to be critical in the DNA recognition process, but do not become part of the completed virus particle. The process of DNA entry into the preformed capsid is thought to involve a special "portal" structure, built at a unique vertex of the icosahedral capsid. The function of the proteins involved in DNA recognition and DNA entry will be examined genetically and biochemically. The findings will contribute to our understanding of the molecular machine that causes packaging of dsDNA chromosomes by the dsDNA viruses. %%% Understanding the process of DNA packaging by these bacteriophage will help in understanding similar processes in less experimentally accessibly but medically important animal virus systems and in developing models for related transport processes such as nuclear RNA transport and bacterial transformation and conjugation.