Emergence of Japanese encephalitis virus genotype V in the Republic of Korea

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis virus (JEV) genotype V reemerged in Asia (China) in 2009 after a 57-year hiatus from the continent, thereby emphasizing a need to increase regional surveillance efforts. Genotypic characterization was performed on 19 JEV-positive mosquito pools (18 pools of <it>Culex tritaeniorhynchus </it>and 1 pool of <it>Cx. bitaeniorhynchus</it>) from a total of 64 positive pools collected from geographically different locations throughout the Republic of Korea (ROK) during 2008 and 2010.</p> <p>Findings</p> <p>Two regions of the JEV genome were sequenced from 19 pools; the envelope gene and the nonstructural protein 5 (NS5)/3'-untranslated region (UTR). Eighteen pools of <it>Culex tritaeniorhynchus </it>and one pool of <it>Cx. bitaeniorhynchus </it>were positive for genotype I and genotype V, respectively. Sequence alignment of the complete E gene from <it>Cx. bitaeniorhynchus </it>showed high amino acid similarity (98.8%) to the Muar strain, characterized as the first report of genotype V, isolated from an encephalitis patient in Malaysia in 1952.</p> <p>Conclusion</p> <p>This study represents the first report of JEV genotype V in the ROK. The reemergence of genotype V in Asia (China and ROK) after more than a half-century and its discovery in <it>Cx. bitaeniorhynchus</it>, a mosquito species previously unknown to carry JEV in the ROK, emphasizes the need for enhanced JE surveillance to monitor the dynamics of JEV strains within the region. Future findings may have implications with regard to JEV vaccination/prevention strategies.</p

The relationship between mosquito abundance and rice field density in the Republic of Korea

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is endemic to the Republic of Korea (ROK) where unvaccinated United States (U.S.) military Service members, civilians and family members are stationed. The primary vector of the JEV in the ROK is <it>Culex tritaeniorhynchus</it>. The ecological relationship between <it>Culex </it>spp. and rice fields has been studied extensively; rice fields have been shown to increase the prevalence of <it>Cx. tritaeniorhynchus</it>. This research was conducted to determine if the quantification of rice field land cover surrounding U.S. military installations in the ROK should be used as a parameter in a larger risk model that predicts the abundance of <it>Cx. tritaeniorhynchus </it>populations.</p> <p>Mosquito data from the U.S. Forces Korea (USFK) mosquito surveillance program were used in this project. The average number of female <it>Cx. tritaeniorhynchus </it>collected per trap night for the months of August and September, 2002-2008, was calculated. Rice fields were manually digitized inside 1.5 km buffer zones surrounding U.S. military installations on high-resolution satellite images, and the proportion of rice fields was calculated for each buffer zone.</p> <p>Results</p> <p>Mosquito data collected from seventeen sample sites were analyzed for an association with the proportion of rice field land cover. Results demonstrated that the linear relationship between the proportion of rice fields and mosquito abundance was statistically significant (R²= 0.62, r = .79, F = 22.72, p < 0.001).</p> <p>Conclusions</p> <p>The analysis presented shows a statistically significant linear relationship between the two parameters, proportion of rice field land cover and log₁₀of the average number of <it>Cx. tritaeniorhynchus </it>collected per trap night. The findings confirm that agricultural land cover should be included in future studies to develop JE risk prediction models for non-indigenous personnel living at military installations in the ROK.</p

Isolation and genomic characterization of Chaoyang virus strain ROK144 from \u3ci\u3eAedes vexansnipponii\u3c/i\u3e from the Republic of Korea

During June 2003, mosquito surveillance was conducted at a US Army installation and a US Military training site 2 km south of the demilitarized zone, Republic of Korea. Mosquitoes were collected using Mosquito MagnetsTM, sorted to species, and assayed for the presence of arboviruses. From the 3,149 mosquitoes that were sorted into126 pools, one Aedes vexan snipponii pool (out of 73 pools) tested positive for flavivirus RNA by reverse transcription-PCR. After isolation from C6/36 cell culture supernatant, the viral genome was sequenced and found to be 98.9% related to Chaoyang virus, a potential arthropod-specific flavivirus. This report details the first identification of Chaoyang virus in the Republic of Korea and highlights its relationship to other flaviviruses

Isolation and genomic characterization of Chaoyang virus strain ROK144 from \u3ci\u3eAedes vexansnipponii\u3c/i\u3e from the Republic of Korea

During June 2003, mosquito surveillance was conducted at a US Army installation and a US Military training site 2 km south of the demilitarized zone, Republic of Korea. Mosquitoes were collected using Mosquito MagnetsTM, sorted to species, and assayed for the presence of arboviruses. From the 3,149 mosquitoes that were sorted into126 pools, one Aedes vexan snipponii pool (out of 73 pools) tested positive for flavivirus RNA by reverse transcription-PCR. After isolation from C6/36 cell culture supernatant, the viral genome was sequenced and found to be 98.9% related to Chaoyang virus, a potential arthropod-specific flavivirus. This report details the first identification of Chaoyang virus in the Republic of Korea and highlights its relationship to other flaviviruses

Arx is required for normal enteroendocrine cell development in mice and humans

AbstractEnteroendocrine cells of the gastrointestinal (GI) tract play a central role in metabolism, digestion, satiety and lipid absorption, yet their development remains poorly understood. Here we show that Arx, a homeodomain-containing transcription factor, is required for the normal development of mouse and human enteroendocrine cells. Arx expression is detected in a subset of Neurogenin3 (Ngn3)-positive endocrine progenitors and is also found in a subset of hormone-producing cells. In mice, removal of Arx from the developing endoderm results in a decrease of enteroendocrine cell types including gastrin-, glucagon/GLP-1-, CCK-, secretin-producing cell populations and an increase of somatostatin-expressing cells. This phenotype is also observed in mice with endocrine-progenitor-specific Arx ablation suggesting that Arx is required in the progenitor for enteroendocrine cell development. In addition, depletion of human ARX in developing human intestinal tissue results in a profound deficit in expression of the enteroendocrine cell markers CCK, secretin and glucagon while expression of a pan-intestinal epithelial marker, CDX2, and other non-endocrine markers remained unchanged. Taken together, our findings uncover a novel and conserved role of Arx in mammalian endocrine cell development and provide a potential cause for the chronic diarrhea seen in both humans and mice carrying Arx mutations

Genetic diversity of Imjin virus in the Ussuri white-toothed shrew (Crocidura lasiura) in the Republic of Korea, 2004-2010

Recently, Imjin virus (MJNV), a genetically distinct hantavirus, was isolated from lung tissues of the Ussuri white-toothed shrew (Crocidura lasiura) captured near the demilitarized zone in the Republic of Korea. To clarify the genetic diversity of MJNV, partial M- and L-segment sequences were amplified from lung tissues of 12 of 37 (32.4%) anti-MJNV IgG antibody-positive Ussuri white-toothed shrews captured between 2004 and 2010. A 531-nucleotide region of the M segment (coordinates 2,255 to 2,785) revealed that the 12 MJNV strains differed by 0-12.2% and 0-2.3% at the nucleotide and amino acid levels, respectively. A similar degree of nucleotide (0.2-11.9%) and amino acid (0-3.8%) difference was found in a 632-nucleotide length of the L segment (coordinates 962 to 1,593) of nine MJNV strains. Phylogenetic analyses, based on the partial M and L segments of MJNV strains generated by the neighbor-joining and maximum likelihood methods, showed geographic-specific clustering, akin to the phylogeography of rodent-borne hantaviruses

Prediction of species composition ratios in pooled specimens of the Anopheles Hyrcanus group using quantitative sequencing

Background Plasmodium vivax is transmitted by members of the Anopheles Hyrcanus Group that includes six species in the Republic of Korea: Anopheles sinensis sensu stricto (s.s.), Anopheles pullus, Anopheles kleini, Anopheles belenrae, Anopheles lesteri, and Anopheles sineroides. Individual Anopheles species within the Hyrcanus Group demonstrate differences in their geographical distributions, vector competence and insecticide resistance, making it crucial for accurate species identification. Conventional species identification conducted using individual genotyping (or barcoding) based on species-specific molecular markers requires extensive time commitment and financial resources. Results A population-based quantitative sequencing (QS) protocol developed in this study provided a rapid estimate of species composition ratios among pooled mosquitoes as a cost-effective alternative to individual genotyping. This can be accomplished by using species- or group-specific nucleotide sequences of the mitochondrial cytochrome C oxidase subunit I (COI) and the ribosomal RNA internal transcribed spacer 2 (ITS2) region as species identification alleles in a two-step prediction protocol. Standard genomic DNA fragments of COI and ITS2 genes were amplified from each Anopheles species using group-specific universal primer sets. Following sequencing of the COI or ITS2 amplicons generated from sets of standard DNA mixtures, equations were generated via linear regression to predict species-specific nucleotide sequence frequencies at different positions. Species composition ratios between An. sineroides, An. pullus and An. lesteri were estimated from QS of the COI amplicons based on the mC.260A, mC.122C and mC.525C alleles at the first step, followed by the prediction of species composition ratios between An. sinensis, An. kleini and An. belenrae based on QS of the ITS2 amplicons using the rI.370G and rI.389T alleles. The COI copy number was not significantly different between species, suggesting the reliability of COI-based prediction. In contrast, ITS2 showed a slightly but significantly higher copy number in An. belenrae, requiring an adjustment of its predicted composition ratio. A blind test proved that predicted species composition ratios either from pooled DNA specimens or pooled mosquito specimens were not statistically different from the actual values, demonstrating that the QS-based prediction is accurate and reliable. Conclusions This two-step prediction protocol will facilitate rapid estimation of the species composition ratios in field-collected Anopheles Hyrcanus Group populations and is particularly useful for studying the vector ecology of Anopheles population and epidemiology of malaria.This research was supported by the Government-wide R&D Fund project for infectious disease research (GFID), Republic of Korea (Grant Number: HG18C0046) and the Armed Forces Health Surveillance Branch, Global Emerg‑ing Infections Surveillance and Response System (AFHSB-GEIS), Silver Spring, MD (ProMIS ID #P0131-20-ME-03). DE Lee was supported in part by Brain Korea 21 Plus Program

SARS-CoV-2 Variant of Concern B.1.1.7: Diagnostic Sensitivity of Three Antigen-Detecting Rapid Tests.

Funder: Foundation for Innovative New DiagnosticsFunder: World Health OrganizationFunder: Ministry of Science, Research and Culture, State of Baden Wuerttemberg, German