Abstract
Antibody-dependent enhancement (ADE) has been considered as one of the mechanism that leads to the development of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). During secondary dengue infection monocytes can be infected by the ADE phenomenon. This study aimed to investigate the proteins involved in ADE of DENV infection in the primary human monocytes isolated from volunteers. The phosphoproteins were used to perform and analyze for protein expression using mass spectrometry (GeLC-MS/MS). The differential phosphoproteins revealed 517 altered proteins compared between isotype- and DENV-specific antibody-treated monocytes. The altered proteins revealed 253 upregulated proteins and 264 downregulated proteins. Approximately 70-80% of altered proteins was classified into binding and catalytic activity proteins, while 20-30% was proteins with molecular function regulator, molecular transducer activity, structural molecule activity, transcription regulator activity or translation regulator activity and transporter activity. Protein disulfide isomerase (PDI), which is an enzyme that had a high-ranking fold change and that catalyzes the formation, breakage, and rearrangement of disulfide bonds within a protein molecule, was selected for further study. PDI was found to be important for dengue virus infectivity during the ADE model. The effect of PDI inhibition was also shown to be involved in the early stage of life cycle by time-of-drug-addition assay. These results suggest that PDI is important for protein translation and virion assembly of dengue virus during infection in human monocytes, and it may play a significant role as a chaperone to stabilize dengue protein synthesis. Moreover, other proteins were further performed by interaction network analysis and found that most structural proteins were interacted together. Alpha-actinin was observed to be altered and may be associated to play important role in viral replication and viral infection in monocytes.
