Replication of positive-strand RNA viruses is a complicated process that involves the virus genome, virus proteins and host factors. In this system, an active replication complex is formed and the central role is played by the viral RNA dependent RNA polymerase. Pepino mosaic virus (PepMV) is a mechanically-transmitted plant virus member of the genus Potexvirus, currently under quarantine in Europe and with great potential of causing serious economical losses to tomato industry. This work extends a recently established bilateral (Greece-Spain) and takes advantage of great expertise of an incoming scientist from Egypt to: 1) purify PepMV membrane-bound replication complexes from infected tomato plants and try to convert them into a soluble, template dependent system for the analysis of viral RNA synthesis, and 2) identify tomato proteins that specifically bind PepMV-encoded proteins and PepMV RNAs (5'- and 3'-untranslated regions). We attempt to establish a model on PepMV to generate valuable data on virus replication with an emphasis on host protein factors. The analysis of viral replication complex components and the identification of the host factors and their role in viral replication constitute two key issues in virology and understanding the mechanisms of viral replication is essential for devising strategies to combat virus-induced diseases. We also intend to extend a research link between three Mediterranean laboratories (Greece, Spain and Egypt) with the view of growing broader and multidisciplinary in the future (e.g. private sector, governmental services, research groups, human capital) given the expansion of the virus and a recent agreement for the establishment of a Euro-Mediterranean Free Trade Area by the year 2010. The proposal capitalizes on the quality of the researcher, the importance of the system chosen in the field of virology and the return potential for the incoming scientist, the host Institute and the expansion of the cooperation.