In this study, we applied a quantitative proteomic approach, based on SILAC, to investigate the interactions of coronaviruses with the secretory pathway of the host cell, with the aim to identify host factors involved in coronavirus replication. Comparison of the
protein profiles of Golgi-enriched fractions of cells that were either mock infected or infected with mouse hepatitis virus revealed the significant depletion or enrichment of 116
proteins. Although ribosomal/
nucleic acid binding proteins were enriched in the Golgi-fractions of mouse hepatitis virus-infected cells,
proteins annotated to localize to several organelles of the secretory pathway were overrepresented among the
proteins that were depleted from these fractions upon
infection. We hypothesized that
proteins, of which the abundance or distribution is affected by
infection, are likely to be involved in the virus life cycle. Indeed, depletion of a small subset of the affected
proteins by using small interfering RNAs identified several host factors involved in
coronavirus infection. Transfection of small interfering RNAs targeting either C11orf59 or Golgi apparatus
glycoprotein 1 resulted in increased virus replication, whereas depletion of vesicle-trafficking
protein vesicle-trafficking
protein sec22b enhanced the release of infectious progeny virus. Overexpression of these
proteins, on the other hand, had a negative effect on virus replication. Overall, our study shows that the SILAC approach is a suitable tool to study host-pathogen interactions and to identify host
proteins involved in virus replication.