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.

Sequence analysis of E/NS1 gene junction of dengue virus type 2 isolated in Brunei.

A preliminary study of dengue infection in Brunei between 2005 and 2006 showed that dengue 2 was the predominant serotype. A total of five DEN-2 isolates were isolated and maintained in the mosquito cell-line, albopictus C6/36. The sequence spanning the envelope and non-structural protein 1 (E/NS1) junction (positions 2311 to 2550) of the isolates were determined and analysed at the amino acid and nucleotide levels. Alignment of the 240 nucleotide sequences among the five isolates showed changes occurring at 7 positions (2.9%) of the region. All but one nucleotide substitution (position 2319, amino acid 742 V --> F) were found at the 3rd position of the codons and were silent mutations. Amino acid homology ranged from 98% to 100%. Sequence divergence of the Brunei isolates varied from 5% to 6.6% compared with dengue-2 prototype New Guinea C strain. Comparison of the Brunei DEN-2 isolates with sixty-five other strains placed them in a cluster containing Indonesian strains isolated in 1973, 1978 and 2004 and Malaysian strains isolated in 1996, 1998 and 1999 in genotype group IV.

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.