Association of viral kinetics, infection history, NS1 protein with plasma leakage among Indonesian dengue infected patients.

OBJECTIVES: Plasma leakage, a hallmark of disease in Dengue virus (DENV) infection, is an important clinical manifestation and is often associated with numerous factors such as viral factors. The aim of this study is to investigate the association of virus serotype, viral load kinetics, history of infection, and NS1 protein with plasma leakage. METHODS: Subjects with fever ≤ 48 hours and positive DENV infection were included. Serial laboratory tests, viral load measurements, and ultrasonography examination to assess plasma leakage were performed. RESULTS: DENV-3 was the most common serotype found in the plasma leakage group (35%). Patients with plasma leakage demonstrated a trend of higher viral load and a longer duration of viremia compared to those without. This was significantly observed on the fourth day of fever (p = 0.037). We found higher viral loads on specific days in patients with plasma leakage in both primary and secondary infections compared to those without. In addition, we also observed more rapid viral clearance in patients with secondary infection. NS1 protein, especially after 4 days of fever, was associated with higher peak viral load level, even though it was not statistically significant (p = 0.470). However, pairwise comparison demonstrated that peak viral load level in the group of patients with circulating NS1 detected for 7 days was significantly higher than the 5-day group (p = 0.037). CONCLUSION: DENV-3 was the most common serotype to cause plasma leakage. Patients with plasma leakage showed a trend of higher viral load and a longer duration of viremia. Higher level of viral load was observed significantly on day 5 in patients with primary infection and more rapid viral clearance was observed in patients with secondary infection. Longer duration of circulating NS1 protein was also seen to be positively correlated with higher peak viral load level although not statistically significant.

Circulation of Various Dengue Serotypes in a Community-Based Study in Jakarta, Indonesia.

Dengue virus (DENV) infection remains to be a serious health problem in Indonesia. Community-based dengue studies to determine circulating DENV serotypes based on the geography and season are limited owing to the expensive cost and significant effort required. Many patients with DENV infection are not hospitalized and many visit the hospital in the later phase of the disease. In this study, we performed active DENV surveillance in a community in Jakarta to study the circulating dengue serotypes; adult febrile patients with fever less than 48 hours were recruited. Disease severity was defined using the World Health Organization (WHO) 1997 guidelines. Rapid NS1 dengue antigen detection was used to screen patients with DENV in the community. Viral culture using the C6/36 cell line, an increased antibody titer on hemagglutination inhibition test and enzyme linked immunosorbent assay, or detection of the viral genome on reverse transcription-polymerase chain reaction was used to confirm DENV infection. Of the 102 patients, 68 (66.7%) were confirmed to have DENV infection, with DENV-2 being the most dominant serotype, followed by DENV-3, DENV-1, and DENV-4, in concordance with several reports of mixed DENV infection. Interestingly, in terms of disease severity, although DENV-3 infection was not the predominant circulating serotype, infection with it tended to cause a more severe disease than infection with DENV-2.

Anti-Hepatitis C Virus Activity of a Crude Extract from Longan (Dimocarpus longan Lour.) Leaves.

Infection with hepatitis C virus (HCV) results in hepatitis C, a disease characterized by chronic infection, cirrhosis, and hepatocellular carcinoma. Currently, the standard therapy is a combination of pegylated interferon-α plus ribavirin with NS3 protease inhibitors. Addition of NS3 protease inhibitors to the standard therapy improves response rates; however, use of NS3 protease inhibitors is also associated with significant adverse effects and an increase in the overall cost of treatment. Therefore, there is a need to develop safe and inexpensive drugs for the treatment of HCV infections. In this study, we examined the antiviral activity of a crude extract from Dimocarpus longan leaves against HCV (genotype 2a strain JFH1). The D. longan crude extract (DL-CE) exhibited anti-HCV activity with a 50% effective concentration (EC50) of 19.4 µg/ml without cytotoxicity. A time-of-addition study demonstrated that DL-CE has anti-HCV activity at both the entry and post-entry steps and markedly blocks the viral entry step through direct virucidal activity with marginal inhibition of virion assembly. Co-treatment of DL-CE with cyclosporine A, an immunosuppressant or telaprevir, an NS3 protease inhibitor, resulted in additive and synergistic antiviral effects, respectively. Our findings suggest that DL-CE may be useful as an add-on therapy candidate for treating HCV infections.

Immunogenicity of a Candidate DNA Vaccine Based on the prM/E Genes of a Dengue Type 2 Virus Cosmopolitan Genotype Strain.

The development of a dengue virus vaccine is a major priority in efforts to control the diseases. Several researchers are currently using the Asian 1 and Asian 2 genotypes as vaccine candidates for dengue type 2 virus (DENV-2). However, in this study, we constructed a recombinant plasmid-based prM/E gene, from a DENV-2 Cosmopolitan genotype strain as a dengue DNA vaccine candidate. The protein expression of the recombinant plasmid in CHO cells was analyzed using an enzyme-linked immunosorbent assay, western blotting, and sucrose gradient sedimentation. After being used to immunize ddY mice three times at doses of 25 or 100 µg, the DNA vaccine induced humoral immune responses. There was no difference in the neutralizing antibody titer (focus reduction neutralization test 50% value) of mice immunized with 25 and 100 µg DNA vaccine doses. When challenged with 3 × 10(5) FFU DENV-2, immunized mice could raise anamnestic neutralizing antibody responses, which were observed at day 4 and day 8 post-challenge. Analysis of immunogenicity using BALB/c mice showed that their antibody neutralization titers were lower than those of ddY mice. In addition, the antibodies produced after immunization and challenge could also neutralize a DENV-2 Asian 2 genotype (New Guinea C) strain. Therefore, the DENV-2 Cosmopolitan genotype may be a DENV-2 vaccine candidate.