Multi-Country Evaluation of the Sensitivity and Specificity of Two Commercially-Available NS1 ELISA Assays for Dengue Diagnosis

Dengue is the most important mosquito-borne viral disease of humans and an enormous public health burden in affected countries. Early, sensitive and specific diagnosis of dengue is needed for appropriate patient management as well as for early epidemic detection. Commercially available assays that detect the dengue virus protein NS1 in the plasma/serum of patients offer the possibility of early and rapid diagnosis. Here we evaluated two commercially available ELISA kits for NS1 detection (Pan-E Dengue Early ELISA and the Platelia™ Dengue NS1 Ag). Results were compared against a reference diagnosis in 1385 patients in 6 countries in Asia and the Americas. Collectively, this multi-country study suggests that the best performing NS1 assay (Platelia) had moderate sensitivity (median 64%, range 34–76%) and high specificity (100%) for the diagnosis of dengue. The combination of NS1 and IgM detection in samples collected in the first few days of fever increased the overall dengue diagnostic sensitivity

Proteína viral NS1 y anticuerpos IgA a virus dengue como nuevos marcadores para el algoritmo diagnóstico de la infección en Cuba

En el presente trabajo se evaluó la proteína viral NS1 y los anticuerpos IgA como marcadores de infección temprana a virus dengue y su posible inclusión en el algoritmo diagnóstico de la enfermedad en el país. La proteína NS1 fue evaluada mediante los sistemas comercialesPlatelia Dengue NS1 Antigen y SD Dengue Duo, mientras que para la IgA se utilizó el ELISA de doble anticuerpo modificado y el sistema comercial MP Diagnostics ASSURE Dengue IgA rapid test. Los ensayos PCR-TR, MAC-ELISA y MEI fueron empleados como referencia en la selección de las muestras y la confirmación de los casos. La proteína NS1 demostró ser un buen marcador de infección temprana, con los mayores porcentajes de positividad en los primeros cuatro días de infección. Se propone un 5to día de colecta con posibilidades diagnósticas. La presencia de IgG antidengue en suero influyó en la detección de NS1 para casos secundarios. Los anticuerpos IgA definen una aparición temprana pero sólo en casos secundarios y con porcentajes de positividad muy bajos. Se propuso incorporar la NS1 a la nueva propuesta de algoritmo diagnóstico para dengue pero no la IgA. Este nuevo algoritmo permitirá un diagnóstico temprano y rápido, contribuyendo al manejo del paciente y control dela transmisión de dengue en el país

Proteína viral NS1 y anticuerpos IgA a virus dengue como nuevos marcadores para el algoritmo diagnóstico de la infección en Cuba

En el presente trabajo se evaluó la proteína viral NS1 y los anticuerpos IgA como marcadores de infección temprana a virus dengue y su posible inclusión en el algoritmo diagnóstico de la enfermedad en el país. La proteína NS1 fue evaluada mediante los sistemas comercialesPlatelia Dengue NS1 Antigen y SD Dengue Duo, mientras que para la IgA se utilizó el ELISA de doble anticuerpo modificado y el sistema comercial MP Diagnostics ASSURE Dengue IgA rapid test. Los ensayos PCR-TR, MAC-ELISA y MEI fueron empleados como referencia en la selección de las muestras y la confirmación de los casos. La proteína NS1 demostró ser un buen marcador de infección temprana, con los mayores porcentajes de positividad en los primeros cuatro días de infección. Se propone un 5to día de colecta con posibilidades diagnósticas. La presencia de IgG antidengue en suero influyó en la detección de NS1 para casos secundarios. Los anticuerpos IgA definen una aparición temprana pero sólo en casos secundarios y con porcentajes de positividad muy bajos. Se propuso incorporar la NS1 a la nueva propuesta de algoritmo diagnóstico para dengue pero no la IgA. Este nuevo algoritmo permitirá un diagnóstico temprano y rápido, contribuyendo al manejo del paciente y control dela transmisión de dengue en el país

OSBPL10, RXRA and lipid metabolism confer African-ancestry protection against dengue haemorrhagic fever in admixed Cubans

International audienceEthnic groups can display differential genetic susceptibility to infectious diseases. The arthro-pod-born viral dengue disease is one such disease, with empirical and limited genetic evidence showing that African ancestry may be protective against the haemorrhagic phenotype. Global ancestry analysis based on high-throughput genotyping in admixed populations can be used to test this hypothesis, while admixture mapping can map candidate protective genes. A Cuban dengue fever cohort was genotyped using a 2.5 million SNP chip. Global ancestry was ascertained through ADMIXTURE and used in a fine-matched corrected association study, while local ancestry was inferred by the RFMix algorithm. The expression of candidate genes was evaluated by RT-PCR in a Cuban dengue patient cohort and gene set enrichment analysis was performed in a Thai dengue transcriptome. OSBPL10 and RXRA candidate genes were identified, with most significant SNPs placed in inferred weak enhancers, promoters and lncRNAs. OSB-PL10 had significantly lower expression in Africans than Europeans, while for RXRA several SNPs may differentially regulate its transcription between Africans and Europeans. Their expression was confirmed to change through dengue disease progression in Cuban patients and to vary with disease severity in a Thai transcriptome dataset. These genes interact in the LXR/ RXR activation pathway that integrates lipid metabolism and immune functions, being a key player in dengue virus entrance into cells, its replication therein and in cytokine production. Knockdown of OSBPL10 expression in THP-1 cells by two shRNAs followed by DENV2 infection tests led to a significant reduction in DENV replication, being a direct functional proof that the lower OSBPL10 expression profile in Africans protects this ancestry against dengue disease. PLOS Pathogens

Evaluation of Zika rapid tests as aids for clinical diagnosis and epidemic preparedness

Background: Development and evaluation of diagnostics for diseases of epidemic potential are often funded during epidemics, but not afterwards, leaving countries unprepared for the next epidemic. United Nations Children's Emergency Fund (UNICEF) partnered with the United States Agency for International Development (USAID) to address this important gap by investing in an advance purchase commitment (APC) mechanism to accelerate the development and evaluation of Zika rapid diagnostic tests (RDTs) for case detection and surveillance. This paper describes the performance evaluation of five Zika RDTs eligible for procurement. Methods: A network of European Union-funded ZikaPLAN sites in Africa, Asia, Latin America with access to relevant serum specimens were selected to evaluate RDTs developed for the UNICEF APC mechanism. A standardised protocol and evaluation panels were developed and a call for specimens for the evaluation panels issued to different sites. Each site contributed specimens to the evaluation from their biobank. Data were collated, analysed and presented to the UNICEF Procurement Review Group for review. Findings: Three RDTs met the criteria for UNICEF procurement of sensitivity and specificity of 85% against a refence standard. The sensitivity/specificity of the ChemBio anti-Zika Virus (ZIKV) immunoglobulin M (IgM) test was 86.4 %/86.7% and the ChemBio ZCD system for anti-ZIKV IgM was 79.0%/97.1%, anti-dengue virus (DENV) IgM 90.0%/89.2%, anti-Chikungunya virus (CHIKV) IgM 90.6%/97.2%. The sensitivity/specificity of the SD Biosensor anti-ZIKV IgM was 96.8 %/90.8%, anti-DENV IgM 71.8%/83.5%, the DENV nonstructural protein 1 (NS1) glycoprotein 90.0%/90.2%, anti- yellow fever virus (YFV) IgM 84.6%/92.4%, anti-CHIKV IgM 86.3%/97.5%. Interpretation: Three RDTs fulfilled the performance thresholds set by WHO and were eligible for UNICEF procurement. These tests will improve the diagnosis of ZIKV and other arboviral infections as well as providing countries with better tools for surveillance and response to future epidemics

The relevant region on chromosome 3 containing the <i>OSBPL10</i> gene

<p><b>(A)</b> Manhattan plot for the association analysis in the 54 fine-matched population structure corrected Cuban pairs of asymptomatic/control versus DHF subjects. <b>(B)</b> The region on chromosome 3, with the haplotype defined by the six significantly associated SNPs indicated by the red box. Genes on the forward sense are indicated in blue; genes on the reverse sense are indicated in light brown. <b>(C)</b> Worldwide frequency of the African (blue), European (red) and other (grey) <i>OSBPL10</i> haplotypes for populations of the 1000 Genomes project, and also for asymptomatic/control and DHF in Cuba. <b>(D)</b> mRNA expression for homozygous genotypes for African and European <i>OSBPL10</i> haplotypes in the 1000 Genomes project transcriptome information.</p

Gene expression for <i>RXRA</i> and <i>OSBPL10</i> in Cuban dengue patients along the course of disease

<p>Data is shown for all Cuban patients, Cuban patients with warning signs, and the Thai transcriptome dataset for whole blood. [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006220#ppat.1006220.ref022" target="_blank">22</a>]</p

Odds ratios of the African <i>OSBPL10</i> haplotype and <i>RXRA</i> alleles in DHF when compared with asymptomatic/control and tests (identified by Y) where statistical significant evidence was detected for each gene.

<p>Odds ratios of the African <i>OSBPL10</i> haplotype and <i>RXRA</i> alleles in DHF when compared with asymptomatic/control and tests (identified by Y) where statistical significant evidence was detected for each gene.</p