Recombinant DENV type 2 NS1n [GST]

Zika virus (ZIKV) causes rash, moderate fever, conjunctivitis, and arthralgia, and has serious connection with neurological complications; therefore, it is a major threat to public health. A rapid and supersensitive method for detecting anti-ZIKV antibodies in humans and animals is thus urgently required. Here, we report an NS1-based luciferase immunosorbent assay (LISA), developed to detect ZIKV-specific IgG. Fusion proteins including a reporter Nano-luciferase (NLuc) and various fragments of ZIKV NS1 protein were expressed in 293 T cells. LISA was performed using the above cell lysates containing the expressed fusion proteins. Sample panels of humans and animals infected with ZIKV were examined for sensitivity of LISA, relative to those of ZIKV RT-PCR, commercial NS1-based ELISA, and micro-neutralization (MN) assays. Specificity and potential cross-reactivity were also evaluated using various convalescent serum samples derived from patients infected with dengue virus (DENV), Japanese encephalitis virus (JEV), and hepatitis C virus (HCV). Results indicated the optimal antigenic domain for anti-ZIKV IgG detection was located within 172-352 amino acids (aa) of ZIKV NS1 protein. NS1-based LISA performs better than commercial ELISA in anti-ZIKV IgG detection. LISA was shown to be at least fourfold more sensitive than commercial ELISA, and could detect anti-ZIKV IgG in various animal hosts without the need of species-specific labeled antibody. This novel assay is potentially useful for the rapid and sensitive detection of anti-ZIKV IgG in human and animal samples.

Introduction: The geographic location of Alappuzha, a district in the South Indian state of Kerala, the distinct weather conditions and frequent natural calamities present a unique ecology that contributes to the prevalence of vector-borne diseases like dengue. Early dengue virus infection can be detected by using a combination of tests on a single serum specimen. Aim: To identify the dengue virus serotypes among hospitalised patients in a South Indian teaching hospital in Alappuzha, Kerala, India. Materials and Methods: Patient samples that tested positive for dengue non-structural protein-1 (NS1) antigen by ELISA were further evaluated for dengue virus RNA by real-time, multiplex reverse transcriptase Polymerase Chain Reaction (PCR) and the serotype was determined. Anonymised patient data was collected using a questionnaire as a data collection tool. The data was analysed for statistical significance. Results: Among 422 non-duplicate patient serum samples received in the Department of Microbiology, in the year 2019, 30 were positive for dengue NS1 antigen by ELISA. Dengue viral RNA was detected in 50% of the samples (15/30). DENV-3 serotype was the most prevalent (nine) followed by DENV-1 (five) and DENV-2 (one). Common presentations of the patients were fever, headache, and myalgia. No statistically significant association was found between a PCR positive result and the presence of warning signs and thrombocytopenia. Conclusion: DENV-3 was the most common serotype in the study population. Early dengue virus infection is associated with varied symptoms.