Neutralizing Dengue Antibody in Pregnant Thai Women and Cord Blood

<div><p>Background</p><p>The WHO ‘Global Strategy for Dengue Prevention and Control, 2012–2020’ addresses the growing need for the treatment of dengue, and targets a 25% reduction in morbidity and 50% in mortality (using 2010 estimates as baseline). Achieving these goals requires future dengue prevention strategies that will employ both potential vaccines and sustainable vector-control measures. Maternally transferred dengue antibody is an important factor in determining the optimal age for dengue vaccination.</p><p>Objectives</p><p>To estimate the seroprevalence of dengue antibodies among mothers living in an area of high endemicity – Ban Pong, Ratchaburi Province – and to assess maternal dengue antibodies transferred to cord blood.</p><p>Materials & Methods</p><p>A cross-sectional study was conducted with 141 pregnant women who delivered at Ban Pong Hospital, Ratchaburi, Thailand. Maternal-cord paired sera were tested for dengue neutralizing (NT) antibody by PRNT₅₀ assay. A ratio of ≥ 1:10 NT titer to dengue serotype was considered seropositive.</p><p>Results</p><p>Most mothers (137/141, 97.2%) had NT antibodies to at least one dengue serotype in their sera. At birth, the proportion of cord sera with NT antibodies to DEN-1, DEN-2, DEN-3, and DEN-4, were high and similar to the sera of their mothers, at 93.6%, 97.2%, 97.9%, and 92.2%, respectively. The dengue geometric mean titers (GMT) in cord blood were significantly higher than the maternal antibodies (p<0.001): highest in DEN-2, followed by DEN-3, and then DEN-1. The GMT of DEN-4 was the lowest among all four serotypes.</p><p>Conclusions</p><p>Dengue infection is highly prevalent among pregnant women in this dengue-endemic area. Most of the cord blood had transferred dengue antibodies, which may have an impact on the disease burden in this population.</p></div

Immunogenic Properties of a BCG Adjuvanted Chitosan Nanoparticle-Based Dengue Vaccine in Human Dendritic Cells

<div><p>Dengue viruses (DENVs) are among the most rapidly and efficiently spreading arboviruses. WHO recently estimated that about half of the world’s population is now at risk for DENV infection. There is no specific treatment or vaccine available to treat or prevent DENV infections. Here, we report the development of a novel dengue nanovaccine (DNV) composed of UV-inactivated DENV-2 (UVI-DENV) and <i>Mycobacterium bovis</i> Bacillus Calmette-Guerin cell wall components (BCG-CWCs) loaded into chitosan nanoparticles (CS-NPs). CS-NPs were prepared by an emulsion polymerization method prior to loading of the BCG-CWCs and UVI-DENV components. Using a scanning electron microscope and a zetasizer, DNV was determined to be of spherical shape with a diameter of 372.0 ± 11.2 nm in average and cationic surface properties. The loading efficacies of BCG-CWCs and UVI-DENV into the CS-NPs and BCG-CS-NPs were up to 97.2 and 98.4%, respectively. THP-1 cellular uptake of UVI-DENV present in the DNV was higher than soluble UVI-DENV alone. DNV stimulation of immature dendritic cells (iDCs) resulted in a significantly higher expression of DCs maturation markers (CD80, CD86 and HLA-DR) and induction of various cytokine and chemokine productions than in UVI-DENV-treated iDCs, suggesting a potential use of BCG- CS-NPs as adjuvant and delivery system for dengue vaccines.</p></div

An example of SNPer usage.

<p>The user loads the SNPer library to current environment before using the SNPer function.</p

Demographic characteristics of 141 pregnant women.

<p>Demographic characteristics of 141 pregnant women.</p

The proportion and geometric mean titer of NT dengue antibodies of 141 maternal and cord paired sera.

<p>Note: p-values for comparisons of seroprevalence are based on symmetry test; p-values for comparisons of GMTs between mother and cord are based on paired test of log (NT)</p><p>The proportion and geometric mean titer of NT dengue antibodies of 141 maternal and cord paired sera.</p

Evaluation of a Dengue NS1 Antigen Detection Assay Sensitivity and Specificity for the Diagnosis of Acute Dengue Virus Infection

<div><p>Background</p><p>Currently, no dengue NS1 detection kit has regulatory approval for the diagnosis of acute dengue fever. Here we report the sensitivity and specificity of the InBios DEN Detect NS1 ELISA using a panel of well characterized human acute fever serum specimens.</p><p>Methodology/Principal Findings</p><p>The InBios DENV Detect NS1 ELISA was tested using a panel composed of 334 serum specimens collected from acute febrile patients seeking care in a Bangkok hospital in 2010 and 2011. Of these patients, 314 were found to have acute dengue by either RT-PCR and/or anti-dengue IgM/IgG ELISA. Alongside the InBios NS1 ELISA kit, we compared the performance characteristics of the BioRad Platelia NS1 antigen kit. The InBios NS1 ELISA Ag kit had a higher overall sensitivity (86% vs 72.8%) but equal specificity (100%) compared to the BioRad Platelia kit. The serological status of the patient significantly influenced the outcome. In primary infections, the InBios NS1 kit demonstrated a higher sensitivity (98.8%) than in secondary infections (83.5%). We found significant variation in the sensitivity of the InBios NS1 ELISA kit depending on the serotype of the dengue virus and also found decreasing sensitivity the longer after the onset of illness, showing 100% sensitivity early during illness, but dropping below 50% by Day 7.</p><p>Conclusion/Significance</p><p>The InBios NS1 ELISA kit demonstrated high accuracy when compared to the initial clinical diagnosis with greater than 85% agreement when patients were clinically diagnosed with dengue illness. Results presented here suggest the accurate detection of circulating dengue NS1 by the InBios DENV Detect NS1 ELISA can provide clinicians with a useful tool for diagnosis of early dengue infections.</p></div

The SNPs composition output chart of three HA sequences from three IFV subpopulations.

<p>Each circle represents the number of SNPs of VIROAF1 (sp1), VIROAF2 (sp2) and VIROAF6 (sp3) for the HA fragment; universal SNPs; unique SNPs; and likely common SNPs.</p

Correlation between maternal and cord blood of DEN-1 to DEN-4 neutralizing antibodies titers.

<p>X-axis shows GMTs of cord blood dengue antibody and Y-axis shows GMTs of maternal dengue antibody of DEN-1, DEN-2, DEN-3 and DEN-4. The Spearman’s rho of DEN1, DEN2, DEN3 and DEN4 are 0.90, 0.92, 0.88 and 0.89 respectively.</p

Detected SNPs in HA gene fragment from sample #VIROAF1 (“AF1_HA.csv”).

<p>Each line describes the SNPs at each position in the HA gene fragment of VIROAF1. For instance, position 51 of the HA gene in VIROAF1 is G while the reference allele is A.</p><p>Detected SNPs in HA gene fragment from sample #VIROAF1 (“AF1_HA.csv”).</p

List of SNP input files ("input_files_list.csv") to be compared by SNPer.

<p>SNPs from eight fragments of sp1, sp 2 and sp3 were compared by SNPer. Each computational SNPs comparison among three viral subpopulations was conducted according to the name of the files listed in each row. For instance, for row #1, SNPer compared the SNPs data in file “AF1_HA.csv” of population 1 (sp1), “AF2_HA.csv” file from population 2 (sp2) and “AF6_HA.csv” file from population 3 (sp3).</p><p>List of SNP input files ("input_files_list.csv") to be compared by SNPer.</p