Membrane binding proteins of coronaviruses

J Alsaadi, Entedar A; Jones, Ian M

CoV nsp 3, 4 and 6 ( Figure 3 ) have fundamental functions in the rearrangement of host cell membranes that are required for the establishment of viral replication-transcription complexes (RTCs), also called replication organelles (RO) [68] . Indeed expression of just these proteins will induce the formation of the double-membrane vesicles (DMVs) and other structures that are characteristic of CoV-infected cells [69] . Replication complexes, intimately bound up with convoluted membrane structures, are a feature of all positive strand RNA viruses and serve at least three functions, probably connected. First, they serve to concentrate viral proteins in a microenvironment where all necessary replication factors are closely associated with the genomic RNA. Second, they exclude host factors so that the competition for resources can be focused on the virus and third they act to separate, as far as possible, the intermediates of replication, which are necessarily double stranded RNA molecules, from the host innate sensors such as TLR7 and MDA-5 [70, 71] .