Showing papers by "Gwong-Jen J. Chang published in 2016"

Measuring Haitian children's exposure to chikungunya, dengue and malaria.

Abstract: Objective To differentiate exposure to the newly introduced chikungunya virus from exposure to endemic dengue virus and other pathogens in Haiti Methods We used a multiplex bead assay to detect immunoglobulin G (IgG) responses to a recombinant chikungunya virus antigen, two dengue virus-like particles and three recombinant Plasmodium falciparum antigens Most (217) of the blood samples investigated were collected longitudinally, from each of 61 children, between 2011 and 2014 but another 127 were collected from a cross-sectional sample of children in 2014 Findings Of the samples from the longitudinal cohort, none of the 153 collected between 2011 and 2013 but 787% (48/61) of those collected in 2014 were positive for IgG responses to the chikungunya virus antigen In the cross-sectional sample, such responses were detected in 96 (756%) of the children and occurred at similar prevalence across all age groups In the same sample, responses to malarial antigen were only detected in eight children (63%) but the prevalence of IgG responses to dengue virus antigens was 606% (77/127) overall and increased steadily with age Spatial analysis indicated that the prevalence of IgG responses to the chikungunya virus and one of the dengue virus-like particles decreased as the sampling site moved away from the city of Leogane and towards the ocean Conclusion Serological evidence indicates that there had been a rapid and intense dissemination of chikungunya virus in Haiti The multiplex bead assay appears to be an appropriate serological platform to monitor the seroprevalence of multiple pathogens simultaneously Resume Objectif Differentier l'exposition au virus chikungunya, recemment introduit, de l'exposition au virus de la dengue et a d'autres pathogenes endemiques en Haiti Methodes Nous avons procede a une analyse multiplex a l'aide de billes pour detecter les reponses de l'immunoglobuline G (IgG) a un antigene recombinant du virus chikungunya, a deux particules pseudovirales de la dengue et a trois antigenes recombinants de Plasmodium falciparum La plupart des echantillons de sang (217) analyses ont ete preleves de facon longitudinale sur chacun des 61 enfants, entre 2011 et 2014, et 127 autres ont ete preleves sur un echantillon transversal d'enfants en 2014 Resultats Dans la cohorte longitudinale, aucun des 153 echantillons preleves entre 2011 et 2013 n'affichait de reponse positive de l'IgG a l'antigene du virus chikungunya, mais 78,7% (48/61) de ceux preleves en 2014 etaient en revanche positifs Dans l'echantillon transversal, des reponses positives ont ete relevees chez 96 enfants (75,6%), avec une prevalence similaire dans tous les groupes d'age Sur ce meme echantillon, des reponses a l'antigene du paludisme n'ont ete detectees que chez huit enfants (6,3%) mais la prevalence globale des reponses de l'IgG aux antigenes du virus de la dengue etait de 60,6% (77/127) et augmentait progressivement avec l'age L'analyse geographique a revele que la prevalence des reponses de l'IgG au virus du chikungunya et a l'une des particules pseudo-virales de la dengue diminuait a mesure que le site d'echantillonnage s'eloignait de la ville de Leogane en direction de l'ocean Conclusion Les preuves serologiques indiquent que la propagation du virus du chikungunya en Haiti a ete rapide et intense L'analyse multiplex a l'aide de billes s'est averee etre une plate-forme serologique appropriee pour controler simultanement la seroprevalence de plusieurs pathogenes Resumen Objetivo Diferenciar la exposicion al nuevo virus chikungunya de la exposicion al virus endemico del dengue y a otros patogenos en Haiti Metodos Se utilizo un ensayo multiplex de microesferas para detectar las respuestas de la inmunoglobulina G (IgG) ante un antigeno recombinante del virus chikungunya, dos particulas similares al virus del dengue y tres antigenos recombinantes de Plasmodium falciparum …

Establishment of an Algorithm Using prM/E- and NS1-Specific IgM Antibody-Capture Enzyme-Linked Immunosorbent Assays in Diagnosis of Japanese Encephalitis Virus and West Nile Virus Infections in Humans

Abstract: The front-line assay for the presumptive serodiagnosis of acute Japanese encephalitis virus (JEV) and West Nile virus (WNV) infections is the premembrane/envelope (prM/E)-specific IgM antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA). Due to antibody cross-reactivity, MAC-ELISA-positive samples may be confirmed with a time-consuming plaque reduction neutralization test (PRNT). In the present study, we applied a previously developed anti-nonstructural protein 1 (NS1)-specific MAC-ELISA (NS1-MAC-ELISA) on archived acute-phase serum specimens from patients with confirmed JEV and WNV infections and compared the results with prM/E containing virus-like particle-specific MAC-ELISA (VLP-MAC-ELISA). Paired-receiver operating characteristic (ROC) curve analyses revealed no statistical differences in the overall assay performances of the VLP- and NS1-MAC-ELISAs. The two methods had high sensitivities of 100% but slightly lower specificities that ranged between 80% and 100%. When the NS1-MAC-ELISA was used to confirm positive results in the VLP-MAC-ELISA, the specificity of serodiagnosis, especially for JEV infection, was increased to 90% when applied in areas where JEV cocirculates with WNV, or to 100% when applied in areas that were endemic for JEV. The results also showed that using multiple antigens could resolve the cross-reactivity in the assays. Significantly higher positive-to-negative (P/N) values were consistently obtained with the homologous antigens than those with the heterologous antigens. JEV or WNV was reliably identified as the currently infecting flavivirus by a higher ratio of JEV-to-WNV P/N values or vice versa. In summary of the above-described results, the diagnostic algorithm combining the use of multiantigen VLP- and NS1-MAC-ELISAs was developed and can be practically applied to obtain a more specific and reliable result for the serodiagnosis of JEV and WNV infections without the need for PRNT. The developed algorithm should provide great utility in diagnostic and surveillance activities in which test accuracy is of utmost importance for effective disease intervention.