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Background: The resolution or aggravation of dengue infection depends on the patient's immune response during the critical phase. Cytokines released by immune cells increase with the worsening severity of dengue infections. Cytokines activate the kynurenine pathway (KP) and the extent of KP activation then influences disease severity., Methods: KP metabolites and cytokines in plasma samples of patients with dengue infection (dengue without warning signs [DWS-], dengue with warning signs [DWS+], or severe dengue) were analyzed. Cytokines (interferon gamma [IFN-ɣ], tumor necrosis factor, interleukin 6, CXCL10/interferon-inducile protein 10 [IP-10], interleukin 18 [IL-18], CCL2/monocyte chemoattractant protein-1 [MCP-1], and CCL4/macrophage inflammatory protein-1beta [MIP-1β] were assessed by a Human Luminex Screening Assay, while KP metabolites (tryptophan, kynurenine, anthranilic acid [AA], picolinic acid, and quinolinic acid) were assessed by ultra-high-performance liquid chromatography and Gas Chromatography Mass Spectrophotometry [GCMS] assays., Results: Patients with DWS+ had increased activation of the KP where kynurenine-tryptophan ratio, anthranilic acid, and picolinic acid were elevated. These patients also had higher levels of the cytokines IFN-ɣ, CXCL10, CCL4, and IL-18 than those with DWS-. Further receiver operating characteristic analysis identified 3 prognostic biomarker candidates, CXCL10, CCL2, and AA, which predicted patients with higher risks of developing DWS+ with an accuracy of 97%., Conclusions: The data suggest a unique biochemical signature in patients with DWS+. CXCL10 and CCL2 together with AA are potential prognostic biomarkers that discern patients with higher risk of developing DWS+ at earlier stages of infection., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Countries around the world are gearing for the transition of the coronavirus disease 2019 (COVID-19) from pandemic to endemic phase but the emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants could lead to a prolonged pandemic. SARS-CoV-2 has continued to evolve as it optimizes its adaptation to the human host and the successive waves of COVID-19 have been linked to the explosion of particular variant of concern. As the genetic diversity and epidemiological landscape of SARS-CoV-2 differ from country to country, this study aims to provide insights into the variants that are circulating in Malaysia. Whole genome sequencing was performed for 204 SARS-CoV-2 from COVID-19 cases and an additional 18,667 SARS-CoV-2 genome sequences were retrieved from the GISAID EpiCoV database for clade, lineage and genetic variation analyses. Complete genome sequences with high coverage were then used for phylogeny investigation and the resulting phylogenetic tree was constructed from 8,716 sequences. We found that the different waves of COVID-19 in Malaysia were dominated by different clades with the L and O clade for first and second wave, respectively, whereas the progressive replacement by G, GH, and GK of the GRA clade were observed in the subsequence waves. Continuous monitoring of the genetic diversity of SARS-CoV-2 is important to identify the emergence and dominance of new variant in different locality so that the appropriate countermeasures can be taken to effectively contain the spread of SARS-CoV-2., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yu, Wong, Liew, Joseph, Zakaria, Nurulfiza, Soe, Kairon, Amin-Nordin and Chee.)

Dengue is a major threat to public health globally. While point-of-care diagnosis of acute/recent dengue is available to reduce its mortality, a lack of rapid and accurate testing for the detection of previous dengue remains a hurdle in expanding dengue seroepidemiological surveys to inform its prevention, especially vaccination, to reduce dengue morbidity. This study evaluated ViroTrack Dengue Serostate, a biosensors-based semi-quantitative anti-dengue IgG (immunoglobulin G) immuno-magnetic agglutination assay for the diagnosis of previous and recent dengue in a single test. Blood samples were obtained from 484 healthy participants recruited randomly from two communities in Petaling district, Selangor, Malaysia. The reference tests were Panbio Dengue IgG indirect and capture enzyme-linked immunosorbent assays, in-house hemagglutination inhibition assay, and focus reduction neutralization test. Dengue Serostate had a sensitivity and specificity of 91.1% (95%CI 87.8-93.8) and 91.1% (95%CI 83.8-95.8) for the diagnosis of previous dengue, and 90.2% (95%CI 76.9-97.3) and 93.2% (95%CI 90.5-95.4) for the diagnosis of recent dengue, respectively. Its positive predictive value of 97.5% (95%CI 95.3-98.8) would prevent most dengue-naïve individuals from being vaccinated. ViroTrack Dengue Serostate's good point-of-care diagnostic accuracy can ease the conduct of dengue serosurveys to inform dengue vaccination strategy and facilitate pre-vaccination screening to ensure safety.

Severe dengue can be lethal caused by manifestations such as severe bleeding, fluid accumulation and organ impairment. This study aimed to investigate the role of dengue non-structural 1 (NS1) protein and host factors contributing to severe dengue. Electrical cell-substrate impedance sensing system was used to investigate the changes in barrier function of microvascular endothelial cells treated NS1 protein and serum samples from patients with different disease severity. Cytokines and metabolites profiles were assessed using a multiplex cytokine assay and liquid chromatography mass spectrometry respectively. The findings showed that NS1 was able to induce the loss of barrier function in microvascular endothelium in a dose dependent manner, however, the level of NS1 in serum samples did not correlate with the extent of vascular leakage induced. Further assessment of host factors revealed that cytokines such as CCL2, CCL5, CCL20 and CXCL1, as well as adhesion molecule ICAM-1, that are involved in leukocytes infiltration were expressed higher in dengue patients in comparison to healthy individuals. In addition, metabolomics study revealed the presence of deregulated metabolites involved in the phospholipid metabolism pathway in patients with severe manifestations. In conclusion, disease severity in dengue virus infection did not correlate directly with NS1 level, but instead with host factors that are involved in the regulation of junctional integrity and phospholipid metabolism. However, as the studied population was relatively small in this study, these exploratory findings should be confirmed by expanding the sample size using an independent cohort to further establish the significance of this study., Competing Interests: The authors have declared that no competing interests exist.

Background: Dengue is an emerging infectious disease that infects up to 390 million people yearly. The growing demand of dengue diagnostics especially in low-resource settings gave rise to many rapid diagnostic tests (RDT). This study evaluated the accuracy and utility of ViroTrack Dengue Acute - a new biosensors-based dengue NS1 RDT, SD Bioline Dengue Duo NS1/IgM/IgG combo - a commercially available RDT, and SD Dengue NS1 Ag enzyme-linked immunosorbent assay (ELISA), for the diagnosis of acute dengue infection., Methods: This prospective cross-sectional study consecutively recruited 494 patients with suspected dengue from a health clinic in Malaysia. Both RDTs were performed onsite. The evaluated ELISA and reference tests were performed in a virology laboratory. The reference tests comprised of a reverse transcription-polymerase chain reaction and three ELISAs for the detection of dengue NS1 antigen, IgM and IgG antibodies, respectively. The diagnostic performance of evaluated tests was computed using STATA version 12., Results: The sensitivity and specificity of ViroTrack were 62.3% (95%CI 55.6-68.7) and 95.0% (95%CI 91.7-97.3), versus 66.5% (95%CI 60.0-72.6) and 95.4% (95%CI 92.1-97.6) for SD NS1 ELISA, and 52.4% (95%CI 45.7-59.1) and 97.7% (95%CI 95.1-99.2) for NS1 component of SD Bioline, respectively. The combination of the latter with its IgM and IgG components were able to increase test sensitivity to 82.4% (95%CI 76.8-87.1) with corresponding decrease in specificity to 87.4% (95%CI 82.8-91.2). Although a positive test on any of the NS1 assays would increase the probability of dengue to above 90% in a patient, a negative result would only reduce this probability to 23.0-29.3%. In contrast, this probability of false negative diagnosis would be further reduced to 14.7% (95%CI 11.4-18.6) if SD Bioline NS1/IgM/IgG combo was negative., Conclusions: The performance of ViroTrack Dengue Acute was comparable to SD Dengue NS1 Ag ELISA. Addition of serology components to SD Bioline Dengue Duo significantly improved its sensitivity and reduced its false negative rate such that it missed the fewest dengue patients, making it a better point-of-care diagnostic tool. New RDT like ViroTrack Dengue Acute may be a potential alternative to existing RDT if its combination with serology components is proven better in future studies.

Dengue virus is one of the most widespread flaviviruses that re-emerged throughout recent decades. The progression from mild dengue to severe dengue (SD) with the complications such as vascular leakage and hemorrhage increases the fatality rate of dengue. The pathophysiology of SD is not entirely clear. To investigate potential biomarkers that are suggestive of pathogenesis of SD, a small panel of serum samples selected from 1 healthy individual, 2 dengue patients without warning signs (DWS-), 2 dengue patients with warning signs (DWS+), and 5 patients with SD were subjected to a pilot analysis using Sengenics Immunome protein array. The overall fold changes of protein expressions and clustering heat map revealed that PFKFB4, TPM1, PDCL3, and PTPN20A were elevated among patients with SD. Differential expression analysis identified that 29 proteins were differentially elevated greater than 2-fold in SD groups than DWS- and DWS+. From the 29 candidate proteins, pathways enrichment analysis also identified insulin signaling and cytoskeleton pathways were involved in SD, suggesting that the insulin pathway may play a pivotal role in the pathogenesis of SD.

Plasma leakage is the main pathophysiological feature in severe dengue, resulting from altered vascular barrier function associated with an inappropriate immune response triggered upon infection. The present study investigated functional changes using an electric cell-substrate impedance sensing system in four (brain, dermal, pulmonary and retinal) human microvascular endothelial cell (MEC) lines infected with purified dengue virus, followed by assessment of cytokine profiles and the expression of inter-endothelial junctional proteins. Modelling of changes in electrical impedance suggests that vascular leakage in dengue-infected MECs is mostly due to the modulation of cell-to-cell interactions, while this loss of vascular barrier function observed in the infected MECs varied between cell lines and DENV serotypes. High levels of inflammatory cytokines (IL-6 and TNF-α), chemokines (CXCL1, CXCL5, CXCL11, CX3CL1, CCL2 and CCL20) and adhesion molecules (VCAM-1) were differentially produced in the four infected MECs. Further, the tight junctional protein, ZO-1, was down-regulated in both the DENV-1-infected brain and pulmonary MECs, while claudin-1, PECAM-1 and VE-cadherin were differentially expressed in these two MECs after infection. Non-purified virus stock was also studied to investigate the impact of virus stock purity on dengue-specific immune responses, and the results suggest that virus stock propagated through cell culture may include factors that mask or alter the DENV-specific immune responses of the MECs. The findings of the present study show that high DENV load differentially modulates human microvascular endothelial barrier function and disrupts the function of inter-endothelial junctional proteins during early infection with organ-specific cytokine production.

Introduction: Dengue has been the most common arbovirus infection worldwide with 2.5 billion people living in over 100 endemic tropical and subtropical regions. Due to the high number of asymptomatic cases and the signs and symptoms being rather unspecific, dengue cases are often under-reported and might influence dengue surveillance programs. Therefore, a rapid, easy to use, inexpensive, and highly sensitive and specific diagnostic tool is essential for early and accurate diagnosis to ease the clinical management of patients as well as for the development of new interventions. Areas covered: This report discusses the contemporary dengue diagnostic tool, mainly from the aspect of molecular diagnosis where an overview of several nuclei acid amplification tests has been included. Potential molecular diagnostic tools such as biosensor and microarray are also discussed in this report. Expert commentary: Rapidness and accuracy in terms of sensitivity and specificity is imperative in dengue diagnosis for both clinical management and surveillance of dengue to ensure early treatment and corrective control measures can be carried out. In the next five years it is expected that there will be newer tests developed using not only the lateral flow techniques but more specifically biosensors and nanotechnology. These new technologies will have to be validated with the appropriate number and category of samples and to address the issue of cross-reactivity.