Subversion of immunoproteasome subunit expression in dengue virus serotype 2-infected HepG2 cells

Abstract: INTRODUCTION: Infection with all serotypes of dengue virus (DV) results in augmented antigen presentation by MHC class I molecules. However, the upregulation of immunoproteasome subunits only results from infection with two serotypes. This study aims to elucidate changes in the expression of immunoproteasome subunits resulting from infection with DV, particularly DV serotype 2 (DV2). METHODS: HepG2 cells were grown in various culture milieu. Total cellular RNA and proteins were extracted and quantified. RESULTS: Results demonstrated sequestration of immunoproteasome subunits LMP2 and LMP7 in DV2-infected cells. CONCLUSIONS: This study provides insights into the mechanisms underlying immune evasion by DV.

Differential expression of aldolase, alpha tubulin and thioredoxin peroxidase in peripheral blood mononuclear cells from dengue fever and dengue hemorrhagic fever patients.

We determined the differential expression levels of proteins in peripheral blood mononuclear cells of patients with dengue fever (DF) and dengue hemorrhagic fever (DHF). Proteins were subjected to two-dimensional electrophoresis, mass spectrometry and Western blot analysis. We identified 8 proteins that were 2-fold or more up-regulated in patients compared to healthy control, three of which, aldolase, thioredoxin peroxidase and alpha tubulin, were related to dengue infection. Both thioredoxin peroxidase and alpha tubulin were over-expressed 4.9 and 3.3 times respectively in DHF compared to DF patients while aldolase was up-regulated 2.2 times in DF compared to DHF patients. Alpha tubulin and thioredoxin peroxidase have the potential to be utilized as biomarkers for DHF.

Inhibitory potential of Quercus lusitanica extract on dengue virus type 2 replication.

This study reports the in vitro inhibitory potential of crude extract of Quercus lusitanica (Q. lusitanica) seeds on the replication of dengue virus type 2 (DEN-2). In vitro antiviral activity of Q. lusitanica extract, assessed in C6/36 cells (cloned cells of Aedes albopictus larvae) employing a virus inhibition assay, showed dose-dependent inhibition. The Q. lusitanica extract at its maximum non-toxic concentration of 0.25 mg/ml completely inhibited 10-1,000 TCID50 of virus, as indicated by the absence of cytopathic effect (CPE). The low dose of Q. lusitanica (0.032 mg/ml) showed 100% inhibition with 10 TCID50 of virus, but only 50% and 25% inhibition with 100 and 1,000 TCID50, respectively. The NS1 is a glycoprotein present in all flaviviruses and appears essential for virus viability. To further evaluate Q. lusitanica extract as an antiviral compound, we investigated the effect of Q. lusitanica extract on the NS1 protein expression of infected C6/36 cells through proteomics technique. The result showed downregulation of NS1 protein expression of infected C6/36 cells after treatment with this extract. In conclusion, we found that Q. lusitanica extract has a good inhibitory effect on the replication of dengue virus type 2, both in conventional cell culture and proteomics technique.