Antibody cross-reactivity confounds testing for dengue virus (DENV) and Zika virus (ZIKV). We evaluated anti-DENV and anti-ZIKV IgG detection using a multiplex serological platform (the pGOLD assay) in patients from the Asunción metropolitan area in Paraguay, which experiences annual DENV outbreaks but has reported few autochthonous ZIKV infections. Acute-phase sera were tested from 77 patients who presented with a suspected arboviral illness from January to May 2018. Samples were tested for DENV and ZIKV RNA by real-time reverse transcription-PCR, and for DENV nonstructural protein 1 with a lateral-flow immunochromatographic test. Forty-one patients (51.2%) had acute dengue; no acute ZIKV infections were detected. Sixty-five patients (84.4%) had anti–DENV-neutralizing antibodies by focus reduction neutralization testing (FRNT50). Qualitative detection with the pGOLD assay demonstrated good agreement with FRNT50 (kappa = 0.74), and quantitative results were highly correlated between methods (P < 0.001). Only three patients had anti–ZIKV-neutralizing antibodies at titers of 1:55–1:80, and all three had corresponding DENV-neutralizing titers > 1:4,000. Hospitalized dengue cases had significantly higher anti-DENV IgG levels (P < 0.001). Anti-DENV IgG results from the pGOLD assay correlate well with FRNT, and quantitative results may inform patient risk stratification.
Address correspondence to Jesse J. Waggoner, 1760 Haygood Dr. NE, Rm. E-132, Atlanta, GA 30322. E-mail: firstname.lastname@example.org
Disclosure: Three authors were employees of Nirmidas Biotech (JSA, JK, and MT) and were involved in sample testing. All data were available to all authors for analysis.
Financial support: Research was supported by NIH grants R21 AI131689 (B. A. P. and J. S. A.) and K08 AI110528 (J. J. W.). In addition, the development of this collaboration was supported by funding from the Consejo Nacional de Ciencia y Tecnología (CONACYT) in Paraguay (A. R.: PVCT16-66 and J. J. W.: PVCT17-65).