The replication of all positive-stranded RNA viruses of eukaryotes is thought to take place at cytoplasmic membranous replication organelles. One of the most prominent types of viral ROs induced by... Show moreThe replication of all positive-stranded RNA viruses of eukaryotes is thought to take place at cytoplasmic membranous replication organelles. One of the most prominent types of viral ROs induced by a number of these viruses, including coronaviruses and arteriviruses, are double-membrane vesicles (DMVs) that contain viral double-stranded RNA. This thesis discusses the formation of these replication organelles by arteri- and coronaviruses and provides new insights in the viral proteins involved. The ultrastructure of the replication organelles was unravelled using both electron microscopy and tomography. Furthermore, this research described in this thesis also shows that the innate immune system in infected cells can prevent the formation of the membrane structures. Show less