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Background: Dengue is an arboviral disease that has a large effect on public health in subtropical and tropical countries. Rapid and accurate detection of dengue infection is necessary for diagnosis and disease management. We previously developed highly sensitive immunochromatographic devices, the TKK 1st and TKK 2nd kits, based on dengue virus (DENV) nonstructural protein 1 detection. However, these TKK kits were evaluated mainly using DENV type 2 clinical specimens collected in Bangladesh, and further validation using clinical specimens of other serotypes was needed. Methods: In the present study, one of the TKK kits, TKK 2nd, was evaluated using 10 DENV-1, 10 DENV-2, 4 DENV-3, 16 DENV-4, and 10 zika virus-infected clinical specimens collected in Bangkok, Thailand. Results: The TKK 2nd kit successfully detected all four DENV serotypes in patient serum specimens and did not show any cross-reactivities against zika virus serum specimens. The IgM and/or IgG anti-DENV antibodies were detected in seven serum specimens, but did not seem to affect the results of antigen detection in the TKK 2nd kit. Conclusion: The results showed that the TKK 2nd kit successfully detected all four DENV serotypes in clinical specimens and confirmed the potential of the kit for dengue diagnosis in endemic countries. [ABSTRACT FROM AUTHOR]

Abstract: Generally, RNA viruses exhibit significant genetic diversity that sometimes effect viral fitness in infected hosts and probably also pathogenesis. Dengue viruses (DENVs) consist of four antigenically distinct serotypes. All the serotypes of DENV can cause mild to severe dengue illnesses. In this study, we examined the sequence variation of DENV in plasma obtained from four patients living in Bangkok who had been secondarily infected with serotype 2 (DENV-2) in 2010. The plasma-derived RNA was directly subjected to reverse transcriptase (RT)–polymerase chain reaction (PCR) at a region including most of domain III of the envelope (E) protein gene, and the PCR products obtained were subjected to clonal sequencing. Using 19–20 clones sequenced from each patient (78 total) plus 601 corresponding sequences from a public database, phylogenetic analysis revealed that the nucleic acid sequences fell into two clusters with clearly different origins. Interestingly, all patients gave sequences indicating that they carried viral populations containing 2, 3 or 5 genetic variants that consisted of one major variant plus one or more minor variants. Three patients showed a major variant from one cluster plus one or more minor components from the other while one showed major and minor variants from a single cluster. Thus, it can be concluded that DENV belonging to two different genetic lineages were co-circulated in Bangkok in 2010. For these two genotype clusters there was also a clear difference in H or Y at the deduced amino acid position 346 (i.e. H346Y) that was consistent for our sequences and 601 sequences from the public database. Thus, one among the mixed viral genotypes introduced into human individuals seems to be variably selected as the predominant component of the carried viral population, and it is possible that the dynamics of this process could influence virus evolution and disease severity. [Copyright &y& Elsevier]