Dengue is an acute febrile disease caused by dengue virus (DENV) that is transmitted by Aedes sp., which causes serious health conditions in many countries. Non-structural protein 1 (NS1) is a co-factor for the RNA replication of this virus, which represents a new strategy for the identification of dengue. Prompt and accurate laboratory diagnosis of this infection is required to assist in patient triage and management, as well as prevent the spread of this infection. In the present study, we tested the potential of surface plasmon resonance (SPR) as a diagnostic tool for dengue infections. NS1 antigen protein was used as an analyte that targets anti-NS1 antibodies, with their interaction resulting in a change in the refractive index. In comparison to currently available gold-standard detection methods [enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR)], SPR showed a similar sensitivity but greater efficiency and simplicity in terms of infection detection. Out of 26 samples collected from patients with dengue in Indonesia, SPR was able to correctly identify all 16 positively infected individuals at a lower concentration and a shorter period of time compared to ELISA and RT-PCR. This study revealed that SPR is a promising tool for DENV detection and potentially other diseases as well.

Background: Vaccination increase immunity against diphtheria, yet will decrease by aging. Therefore, boosters are needed to be done regularly. Objectives: This study aims to determine the immunity to diphtheria for the population of 16 years old and above. Methods: The sample of study were 295 collected blood serums by Riskesdas project in 2013, the criteria was above 15 years of age and originating from the Provinces of Central Java or East Java inclusively. Immunity assessment was based on antibody titer (IgG) against diphtheria using Vero Cell cytotoxicity test. Statistical analysis was performed using the X2 test. Results: The full protective IgG titer (>0.1 IU/ml) at the age of 16-20 years included 75% sample with a geometric mean titer (GMT) of 0.19 IU/ml. Yet, at the age of 21-60 years and > 60 years, full protective IgG titers only cover 45.5% and 33.3% sample with GMT respectively 0.06 IU / ml. Statistical analysis showed the relationship between age and immune status with p-value 0.003. Otherwise, no relationship between the status of immunity with sex and residency with p-values of 0.16 and 0.43. Conclusions: The immune status against diphtheria at the age of above 15 years decreases with aging. Keywords: Adult; diphtheria; Indonesia; serology.