Dengue virus NS1 antigen ELISA
Acute dengue virus infections can be diagnosed at an early stage using a new ELISA which detects the viral antigen NS1 (non-structural protein 1). NS1 is a highly conserved glycoprotein which is present in the serum of infected persons at the onset of clinical symptoms in both primary and secondary infections. It is detectable before the appearance of IgM and IgG antibodies in first infections and also before IgM in subsequent infections, and it remains detectable for a longer time frame than viral RNA. The combined analysis of NS1 and specific antibodies enables reliable diagnosis of dengue virus infections in all stages. The microplates of the new Dengue Virus NS1 ELISA are coated with monoclonal anti-NS1 antibodies, which specifically detect the NS1 protein from all dengue virus serotypes (DENV 1, 2, 3 and 4). The ELISA has been extensively evaluated in clinical studies and quality assessment schemes, and shows a high sensitivity and specificity. NS1 detection by ELISA offers the additional advantage of being technically simpler and less expensive than other early-stage detection methods such as viral RNA analysis by reverse transcription PCR, or virus cultivation. Serological detection of specific antibodies provides confirmation of acute infections at later stages and past infections. Anti-dengue virus antibodies can be determined by ELISA based on highly purified viral particles from dengue virus-infected cells, or by indirect immunofluorescence using a mosaic of four cell substrates, each infected with a different serotype. To exclude cross reactions with other structurally similar flaviviruses, a further BIOCHIP mosaic of cells infected with e.g. tick-borne encephalitis virus, West Nile virus, yellow fever virus and Japanese encephalitis virus can be incubated in parallel.
