Serodiagnosis of dengue virus infection using commercially available antibody and NS1 antigen ELISAs D Granger a , YS Leo b , LK Lee b , ES Theel a, ⁎ a Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA b Institute of Infectious Diseases and Epidemiology, Communicable Disease Centre, Tan Tock Seng Hospital, Singapore abstract article info Article history: Received 14 December 2016 Received in revised form 23 March 2017 Accepted 27 March 2017 Available online xxxx Keywords: Dengue virus NS1 antigen Antibody Accuracy of the InBios DENV Detect IgM, IgG and NS1 antigen (Ag) ELISAs (Seattle, WA) for detection of dengue virus (DENV) infection were evaluated using 100 retrospectively selected sera from acutely febrile patients pre- senting to a Singapore hospital. The InBios DENV NS1, IgM and IgG ELISAs had an overall sensitivity of 83.6%, 40% and 58.2% and an overall specificity of 97.8%, 97.8% and 55.6%, respectively. Simultaneous testing for NS1 and IgM-antibodies yielded a sensitivity and specificity of 85.5% and 95.5%, respectively, which did not significantly differ from testing for NS1 Ag alone. Using sera positive for IgM- or IgG-class antibodies to six common arbovi- ruses, the InBios IgM and IgG ELISAs showed an overall analytic specificity of 89.2% and 66.4%, respectively. This study suggests that recent DENV infection can reliably be detected by the InBios NS1 Ag ELISA alone and that InBios DENV IgG reactivity should be interpreted with caution. © 2017 Elsevier Inc. All rights reserved. 1. Introduction Dengue virus (DENV) remains the greatest arboviral threat world- wide, with recent cartographic modeling suggesting that approximately 390 million new infections (range: 284–528 million) occur annually (Bhatt et al., 2013). DENV, a complex of four serotypes (DENV 1–4), is a member of the Flavivirus genus and is transmitted by Aedes species (primarily A. aegypti) mosquitoes, which inhabit both tropical and sub- tropical regions worldwide (Guzman et al., 2010). DENV is maintained in the environment by human and non-human primates and the lack of a secondary, amplifying host, alongside the widespread endemicity of A. aegypti, accounts for the impressive global distribution of all four DENV serotypes. While the majority of primary DENV infections are subclinical, individuals who develop disease commonly present with self-limiting fever, headache, anorexia and fatigue approximately 5– 9 days following the mosquito bite (Hynes, 2012). A small percentage of patients are at-risk for more severe disease. To better identify these individuals, the World Health Organization (WHO) has established criteria for stratification of dengue infections based on the presence or absence of certain warning signs (e.g., persistent vomiting, fluid accu- mulation, mucosal bleeding, liver enlargement, elevated hematocrit, etc.) (WHO, 2009). These disease severity categories include dengue without warning signs, dengue with warning signs and severe dengue, which can manifest with significant plasma leakage, hemorrhage and organ impairment. Early detection and prompt management of these cases is associated with patient morbidity of less than 1% (Pal et al., 2014; WHO, 2012). Diagnostic testing for DENV in the United States, including molecular assays for detection of DENV RNA by real-time reverse transcriptase PCR (RT-PCR) and serologic methods is largely localized to select public health and commercial reference laboratories. Selection between these methods should be based on the timing of specimen collection with respect to symptom onset. Briefly, dengue viremia is detectable as early as two days prior and up to five days following symptom onset, making RT-PCR for DENV ideal during acute disease (Erra et al., 2013). An alternative marker for acute DENV infection is nonstructural protein 1 (NS1), a DENV glycoprotein released from infected host cells; NS1 antigenemia overlaps with DENV viremia (Anderson et al., 2014; Flamand et al., 1999). The DENV NS1 protein is detectable up to nine days post symptom onset in most patients and provides a high level of specificity for DENV (Guzman et al., 2010; Pal et al., 2014). Final- ly, serologic evaluation for DENV-specific IgM- and IgG-class antibodies remains the most commonly used diagnostic method, likely due to wider availability and lower cost; however antibody detection has sev- eral significant limitations. These include the delay associated with DENV-specific IgM seroconversion (3–5 days), prolonged sero- persistance of IgM- and IgG-class antibodies following recovery, and cross-reactivity with other closely related flaviviruses (Hunsperger et al., 2009; Mansfield et al., 2011). The objective of this study was to evaluate the performance charac- teristics, including diagnostic accuracy and analytic specificity, of the InBios DENV Detect™ NS1 antigen, IgM Capture and IgG ELISAs (Seattle, WA). The simultaneous assessment of all three of these serologic assays on the same specimens has not been performed previously. While Diagnostic Microbiology and Infectious Disease xxx (2017) xxx–xxx ⁎ Corresponding author. Tel.: +1 507 284 3743; fax: +1 507 266 4341. E-mail address: theel.elitza@mayo.edu (E.S. Theel). http://dx.doi.org/10.1016/j.diagmicrobio.2017.03.015 0732-8893/© 2017 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Diagnostic Microbiology and Infectious Disease journal homepage: www.elsevier.com/locate/diagmicrobio Please cite this article as: Granger D, et al, Serodiagnosis of dengue virus infection using commercially available antibody and NS1 antigen ELISAs, Diagn Microbiol Infect Dis (2017), http://dx.doi.org/10.1016/j.diagmicrobio.2017.03.015