engleski

Endosomal remodelling during early phase of murine cytomegalovirus infection

Mouse cytomegalovirus (MCMV) is a large DNA virus with a number of genes that manipulate cellular functions. Among many other alterations, MCMV reorganizes endosomal system of the host cell in order to establish environment for virion envelopment. That process starts early in the infection and continues throughout the entire replication cycle until the assembly compartment is established at the beginning of the late phase of infection. Early events of endosomal reorganization were in the focus of our study. We infected Balb 3T3 fibroblasts with ΔMC95.15 – MCMV with deleted m138 gene that encodes a protein with immunoglobulin binding capacity (viral FcR). Selected markers of endocytic pathways were followed by immunofluorescence and confocal microscopy. The intracellular routes were determined by functional assays. Western-blot analysis was used to elucidate intracellular expression of endosome regulating proteins (Rab and Arf family). The endosomal remodeling was apparent at 6 hrs post infection as juxtanuclear vacuole-tubular compartment(s) that retained early endosomal cargo molecules (TfR, MHC-I) and markers (EEA1, Rab5). This compartment was characterized using a set of early endosomal as well as “early” (MLN64) and “late” (NPC1) late endosomal markers. The endosomal system reshaping was associated with rapid downregulation of Rab proteins that regulate endosomal recycling (Rab4, Rab22a, Rab11, Arf1), early-to-late endosome transit (Rab7 and Rab9) or late endosomal recycling (Rab27a). This suggests that MCMV uses a mechanism of rapid Rab or Arf protein degradation in order to reshape endosomal system.

MCMV; endosomal remodelling; endosomal markers

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