Real-World Study on Chai-Shi-Jie-Du Granules for the Treatment of Dengue Fever and the Possible Mechanisms Based on Network Pharmacology.

Objectives: Traditional Chinese medicine (TCM) is a widely used method for treating dengue fever in China. TCM improves the symptoms of patients with dengue, but there is no standard TCM prescription for dengue fever. This real-world study aimed to evaluate the effects of Chai-Shi-Jie-Du (CSJD) granules for the treatment of dengue fever and the underlying mechanisms. Methods: We implemented a multicenter real-world study, an in vitro assay and network pharmacology analysis. Patients from 5 hospitals in mainland China who received supportive western treatment in the absence or presence of CSJD were assigned to the control and CSJD groups between 1 August and 31 December 2019. Propensity score matching (PSM) was performed to correct for biases between groups. The clinical data were compared and analyzed. The antidengue virus activity of CSJD was tested in Syrian baby hamster kidney (BHK) cells using the DENV2-NGC strain. Network pharmacological approaches along with active compound screening, target prediction, and GO and KEGG enrichment analyses were used to explore the underlying molecular mechanisms. Results: 137 pairs of patients were successfully matched according to age, sex, and the time from onset to presentation. The time to defervescence (1.7 days vs. 2.5 days, P < 0.05) and the disease course (4.1 days vs. 6.1 days, P < 0.05) were significantly shorter in the CSJD group than those in the control group. CSJD showed no anti-DENV2-NGC virus activity in BHK cells. Network pharmacology analysis revealed 108 potential therapeutic targets, and the top GO and KEGG terms were related to immunity, oxidative stress response, and the response to lipopolysaccharide. Conclusions: CSJD granules exhibit high potential for the treatment of dengue fever, and the therapeutic mechanisms involved could be related to regulating immunity, moderating the oxidative stress response, and the response to lipopolysaccharide.

The whole-genome sequencing of prevalent DENV-1 strains during the largest dengue virus outbreak in Xishuangbanna Dai autonomous prefecture in 2019.

In 2019, a serious dengue virus (DENV) infection broke out in the Xishuangbanna Dai Autonomous Prefecture, China. Therefore, we conducted a molecular epidemiological analysis in people that contracted DENV serotype 1 (DENV-1) during this year. We analyzed the molecular epidemiology of six DENV-1 epidemic strains in 2019 by full-length genome sequencing, amino acid mutation site analysis, evolutionary tree analysis, and recombination site comparison analysis. Through the analysis of amino acid mutation sites, it was found that DENV-1 strain (MW386867) was different from the other five epidemic DENV-1 strains in Xishuangbanna in 2019. MW386867 had unique mutation sites at six loci. The six epidemic DENV-1 strains in Xishuangbanna in 2019 were divided into two clusters. MW386867 was highly similar to the MG679800 (Myanmar 2017), MG679801 (Myanmar 2017), and KC172834 (Laos 2008), and the other five strains were highly similar to JQ045660 (Vietnam 2011), FJ176780 (GuangDong 2006). Genetic recombination analysis revealed that there was no recombination signal in the six epidemic DENV-1 strains in Xishuangbanna in 2019. We speculate that the DENV-1 epidemic in 2019 has a co-epidemic of local strains and cross-border strains.

Corrigendum: Clinical Characteristics and Risk Factors for Severe Dengue Fever in Xishuangbanna, During the Dengue Outbreak in 2019.

[This corrects the article DOI: 10.3389/fmicb.2022.739970.].

Development and validation of a survival prediction model for patients received mechanical ventilation in the intensive care unit: a large sample size cohort from the MIMIC database.

BACKGROUND: Mechanical ventilation remains one of the primary management measures for critically ill patients in intensive care units (ICUs). However, previous studies on the prognosis prediction of ICU patients received mechanical ventilation were limited. This study was to develop and validate a nomogram for predicting short- and long-term survival among patients who received mechanical ventilation in the ICU. METHODS: This was a retrospective cohort study with a 3-year follow-up. Demographic, laboratory, clinical data of 16,775 participants aged ≥18 years who received mechanical ventilation in the ICU were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. The outcomes of this study were 1-month, 3-month, 1-year, and 3-year survival. All eligible patients were randomly classified into the training and testing groups with a ratio of 7:3. A multivariate Cox regression in the training group was used to explore the predictors and develop the predictive nomogram. Internal and subgroup validations were performed, and the C-index was calculated to estimate the predictive performance of the nomogram. The time-dependent receiver operating characteristic curves were drawn, and corresponding areas under the curve (AUC) were calculated. RESULTS: Totally 6,291 patients died during the follow-up duration. Age, gender, ethnicity, ICU type, comorbidity, days of mechanical ventilation, white blood cell count, blood urea nitrogen, the fraction of inspiration O2, Sequential Organ Failure Assessment scores, and the Glasgow coma score were predictors of the survival of ICU patients who received mechanical ventilation (P<0.05). The C-index of the nomogram was 0.819 and was validated in the testing group at 0.816. The AUCs for the prognostic nomogram for 1-month, 3-month, 1-year, and 3-year survival were 0.889, 0.892, 0.882, and 0.866, respectively. CONCLUSIONS: This nomogram showed good predictive performance for short- and long-term survival in ICU patients treated with mechanical ventilation, which may be a useful tool for clinicians to assess the prognosis of patients and to adjust treatment strategies in time.

Clinical Characteristics and Risk Factors for Severe Dengue Fever in Xishuangbanna, During the Dengue Outbreak in 2019.

Background: Dengue poses a large burden on the public health systems worldwide. severe dengue (SD) could lead to more serious clinical symptoms and even death. This study aimed to identify the cause of SD in a clinical trial during the dengue outbreak in Xishuangbanna in 2019, and could provide new insights into the pathogenic mechanisms of SD. Methods: Mosquito-borne viral (DENV, JEV, and CHIKV) infections were identified. The epidemiological factors and clinical symptoms of inpatients in Xishuangbanna were recorded. The IgG and IgM levels in the serum of dengue inpatients were evaluated, and secondary infections were identified. Then, the structural proteins (C/PrM/E) were sequenced and compared with those of the same type of DENV in the same area as before, and their structures were predicted by the SWISS-MODEL (expasy.org). The full-length viral genomes were sequenced and aligned with representative strains by BioEidt or MEGA 5.0. Results: In this outbreak, the clinical symptoms were more serious in SD. The proportion of SD inpatients of male and Han nationality was larger than that of dengue fever (DF) inpatients (p < 0.05). DENV-2 infection was the majority in DF, with 45 inpatients. However, DENV-1 infection was the most common SD, with 54 inpatients. There were 3 DENV-3-positive inpatients in the DF group and 6 ZIKV-positive inpatients in the SD group. A secondary infection accounted for 76.47% (78 cases) of SD inpatients, but secondary infections were only in 20% (17 cases) of DF inpatients. In the three-dimensional structure of protein analysis, the C/PrM/E of DENV-1 and DENV-2 showed more stability than previous epidemic strains, while DENV-3 in 2019 showed a looser spatial structure. After a complete genome sequencing and analysis, all six DENV-2 strains belonged to cosmopolitan, five of which clustered into one branch. The GC/AT of the five strains decreased from 2014 to 2018. Compared with DF strains, SD strains had no mutations of commonness. Conclusions: SD may related to secondary heteromorphic dengue in Xishuangbanna in 2019. The coinfection of ZIKV could be another related factor for SD. The currently datas were very limited and only suggestive.

Co-circulation of three dengue virus serotypes led to a severe dengue outbreak in Xishuangbanna, a border area of China, Myanmar, and Laos, in 2019.

Dengue fever was included in the top 10 global health threats announced by the World Health Organization (WHO) in early 2019. In some southern provinces of China, autochthonous outbreaks have also been reported over the last decade. An unexpected large outbreak of dengue fever was reported in Xishuangbanna, a border area of China, Myanmar, and Laos, in 2019. Among the 226 hospitalized cases, 90 were diagnosed as severe dengue according to the 2009 WHO guidelines. Serotyping and phylogenetic analyses of envelope gene sequences from 246 randomly selected samples showed that three serotypes of dengue virus were co-circulating in this outbreak, which is very rare in this area. Dengue virus serotype 1 (DENV-1, genotype I) and serotype 2 (DENV-2, Cosmopolitan genotype and Asian genotype) were the main pathogenic agents of this outbreak. Dengue virus serotype 3 (DENV-3) epidemic strains were classified as genotype III and formed a close cluster with the Thailand 2015 epidemic strain. The co-circulation may have led to more serious clinical symptoms and a larger scale epidemic. This finding is of great importance in understanding the circulation of DENV and to strengthen the detection and management of dengue fever in border areas.

Three Novel Genetic Variants in the FAM110D, CACNA1A, and NLRP12 Genes Are Associated With Susceptibility to Hypertension Among Dai People.

BACKGROUND: Although the genetic factors associated with hypertension remain unknown, genetic variations in genes related to ion channels, inflammation, and the cell cycle may affect susceptibility to hypertension. In the present study, the association between hypertension and 10 candidate single-nucleotide polymorphisms (SNPs) was evaluated among Chinese Dai people, who have a smaller gene pool than Han individuals. METHODS: A total of 1,193 samples from Dai people were collected, including 488 with hypertension and 705 with normal blood pressure. Based on the preliminary results of whole-genome sequencing among pools of individuals (Pool-seq), 10 candidate SNPs in 6 genes (FAM110D, ADD1, RAG1, CACNA1C, CACNA1A, and NLRP12) were genotyped in the case and control groups by multiplex PCR for SNP genotyping with next-generation sequencing (MultiPCR-NGS). The relationship between hypertension and each candidate SNP was evaluated using the χ 2 test and multiple logistic regression analysis. RESULTS: The χ 2 test showed that the allele frequencies of rs3748856 in FAM110D, rs139118504 in CACNA1A, and rs34436714 in NLRP12 were significantly different between the case and control groups (P < 0.005). After adjusting for age, body mass index, total cholesterol, triglyceride, and low-density lipoprotein, logistic regression analyses revealed that the association between the 3 SNPs and hypertension among Dai people remained significant (P = 0.012, 2.71 × 10-4, and 0.017, respectively). CONCLUSIONS: These findings indicate that there may be different molecular pathogeneses of hypertension among Dai people, which should be noted in future studies.

Molecular characterization of structural protein genes of dengue virus serotype 1 epidemic in Yunnan, Southwest China, in 2018.

A dengue virus serotype 1 (DENV-1) epidemic occurred from October to December 2018 in Xishuangbanna, Yunnan, Southwest China, neighboring Myanmar, Laos, and Vietnam. In this study, we investigated the molecular characteristics, evolution, and potential source of DENV from Xishuangbanna. The C (capsid), prM (premembrane), and E (envelope) genes of DENV isolated from 87 serum samples obtained from local patients were amplified and sequenced, and the sequences were evaluated by identification of mutations, phylogenetic and homologous recombination analysis, and secondary structure prediction. Phylogenetic analysis showed that all of the epidemic DENV strains from Xishuangbanna could be grouped in a branch with DENV-1 isolates, and were most similar to the Fujian 2005 (China, DQ193572) and Singapore 2016 (MF314188) strains. When compared with DENV-1SS (the standard strain), there were 31 non-synonymous mutations, but no obvious homologous recombination signal was found. Secondary structure prediction showed that some changes had occurred in a helical region in proteins of the MN123849 and MN123854 strains, but there were few changes in the disordered region. This study reveals the molecular characteristics of the structural genes of the Xishuangbanna epidemic strains in 2018 and provides a reference for molecular epidemiology, infection, and pathogenicity research and vaccine development.

The effects of estradiol on inflammatory and endothelial dysfunction in rats with preeclampsia.

Preeclampsia (PE), a hypertensive disorder during pregnancy, has adverse effects to both the mother and the fetus. Maternal inflammatory and vascular endothelial dysfunction are important factors in the pathogenesis of PE. The present study aimed to investigate the effects of estradiol (E2) on inflammatory and endothelial dysfunction in an N (omega)­nitro­L­arginine methyl ester (L­NAME)­induced rat model of PE. Adult pregnant female Sprague­Dawley rats were divided into four equal groups between days 7 and 11 of gestation and treated as follows: i) Pregnant rats receiving daily intraperitoneal (i.p.) injections of equal volume of 0.9% normal saline (NS) (Control group, n=12); ii) pregnant rats receiving daily i.p. injections of L­NAME at 50 mg/kg (L­NAME group, n=12); iii) pregnant rats receiving a daily i.p. injection of 50 mg/kg L­NAME and NS from day 11 (L­NAME + NS group, n=12); and iv) pregnant rats receiving daily i.p. injections of 50 mg/kg L­NAME and 100 µg/kg/day E2 from day 11 (L­NAME + E2 group, n=12). On day 21, blood pressure (BP) and the level of 24­h urine protein in the maternal rats, fetal weight and percentage of stillbirths following a cesarean section were recorded. The activities of nitric oxide (NO) and inducible NO synthase (iNOS), the levels of inflammatory cytokines [interleukin (IL)­1ß, IL­6, interferon­Î³ and monocyte chemoattractant protein­1], adherence factors (CD49d, intracellular adhesion molecule 1 and lymphocyte function­associated antigen­1) and uterine angiogenic status (Fms­like tyrosine kinase­1, vascular cell adhesion molecule and matrix metalloproteinase 2/9) were also assessed. In addition, the histopathology of the placenta, the expression of estrogen receptor α 36 (ERα36), ERα, ERß and G protein­coupled ER, as well as the activation of the toll­like receptor 4 (TLR4) signaling pathway (TLR4, myeloid differentiation primary response 88, IL­1 receptor­associated kinase 4 and tumor necrosis factor receptor­associated factor 6) were evaluated by H&E staining, immunofluorescence and western blot assays. Treatment with L­NAME increased the BP, urine protein and rate of stillbirths and suppressed fetal weight compared with those in the control group. The L­NAME­induced effects were attenuated by the administration of E2. In addition, the administration of E2 decreased inflammation and NO levels and altered the uterine angiogenic status. The histological analysis of PE rat placenta in the E2­treated group confirmed the effects on biochemical parameters. Of note, E2 treatment significantly suppressed the TLR4 signaling pathway. In the rat model of PE, adverse outcomes including BP, fetal rat weight and proteinuria, high neonatal death rate, inflammatory response, oxidative stress and endothelial dysfunction were attenuated by exogenous E2 administration, which may present a novel approach for the clinical treatment of PE.

Fish oils protects against cecal ligation and puncture­induced septic acute kidney injury via the regulation of inflammation, oxidative stress and apoptosis.

Septic acute kidney injury (AKI) is usually caused by sepsis. ω3 fatty acid has been reported to suppress sepsis­induced organ dysfunction to a certain degree. The present study aimed to investigate the effects of ω3 fatty acid in septic renal injury. Sprague Dawley rats were used to establish a cecal ligation and puncture (CLP) model in order to mimic the development of septic injury. The rats were treated with dexamethasone and fish oils (FOs) for 4 days prior to CLP. Alterations in the morphology of the tissues, the renal function and the induction of inflammation, oxidative stress and apoptosis were evaluated. The effects of FOs on nuclear factor­κB (NF­κB), JAK2/STAT3 and p38­MAPK were determined. The rats of the CLP model group exhibited low survival rates and increased expression of serum creatine, blood urea nitrogen, neutrophil gelatinase­associated lipocalin, kidney injury molecule­1 and of proinflammatory cytokines. In addition, the levels of the markers of oxidative injury and apoptosis were increased. The induction of renal injury was notably reversed by administration of dexamethasone and FOs. The expression levels of the protein markers involved in inflammation and apoptosis were measured and the results indicated that FOs inhibited JAK/STAT3 and p­38MAPK signaling, while they concomitantly increased the expression of NF­κB. The present study highlighted that FOs improve CLP­induced mortality and renal injury by inhibiting inflammation, oxidative stress and apoptosis.

Molecular characterization of the viral structural gene of the first dengue virus type 1 outbreak in Xishuangbanna: A border area of China, Burma and Laos.

BACKGROUND: Xishuangbanna, a border area of China, Burma and Laos, had its first major DENV-1 outbreak in 2017. This study aims to explore the genetic characterization, potential source and evolution of the viruses in outbreak. METHODS: The structural protein C/prM/E genes of viruses isolated from local residents or Burmese travelers were sequenced followed by mutation, phylogenetic, homologous recombination, molecular clock and demographic reconstruction analysis. RESULTS: Phylogenetic analysis revealed that all of the strains were classified as three cluster of DENV-1. Cluster 1, 2 and 3 were most similar to China Guangzhou 2011, China Hubei 2014 and Laos 2008 strain, respectively. Among 236 base mutations, 31 caused nonsynonymous mutations when compared with the DENV-1SS. No homologous recombination signal was discovered. The structural protein of these strains had similar three-dimensional structure. Only site 434 showed differences among five predicted protein binding sites. Molecular clock phylogenetic and demographic reconstruction analysis showed that DENV-1 became highly diversified in 1972 followed by a slightly decreased period until 2017. CONCLUSIONS: Dengue isolated strains show diversification between Burma and China. Amino acid substitution (I440T) may lead to weakened virulence of the epidemic strains. DENV-1 became highly diversified in 1972 followed by a slightly decreased period.

Netrin-1 prevents the attachment of monocytes to endothelial cells via an anti-inflammatory effect.

Netrin-1 is best known for its function guiding axon growth and migration. Netrin-1 has been shown to be involved in regulating cardiovascular function. In this study, we aimed to understand the biological role of Netrin-1 and its receptor Unc5b in endothelial cells. Our results demonstrate that Unc5b was moderately expressed in human aortic endothelial cells (HAECs) and TNF-α had a dose-dependent inhibitory effect on Unc5b level. Netrin-1 potently suppressed TNF-α-induced vascular adhesion molecules VCAM-1, ICAM-1, E-selectin and blocked the adhesion of monocytes to endothelial cells. Netrin-1 also suppressed TNF-α-induced production of cytokines including MCP-1, IL-1ß, and IL-6. Importantly, Netrin-1 suppressed toll like receptor 4 (TLR4) expression and prevented NF-κB activation. Mechanistically, Netrin-1 reduced TNF-α-induced IKK and IκBα activation and prevented degradation of IκBα. Netrin-1 reduced nuclear accumulation of p65 and strongly suppressed NF-κB promoter activation. Collectively, our data demonstrated that signaling of Netrin-1 and its receptor Unc5b had an anti-inflammatory effect in endothelial cells. Netrin-1 signaling could be imperative for normal endothelial function.

Molecular Characterization of Dengue Virus Serotype 2 Cosmospolitan Genotype From 2015 Dengue Outbreak in Yunnan, China.

In 2015, a dengue outbreak with 1,067 reported cases occurred in Xishuangbanna, a city in China that borders Burma and Laos. To characterize the virus, the complete genome sequence was obtained and phylogenetic, mutation, substitution and recombinant analyses were performed. DENV-NS1 positive serum samples were collected from dengue fever patients, and complete genome sequences were obtained through RT-qPCR from these serum samples. Phylogenetic trees were then constructed by maximum likelihood phylogeny test (MEGA7.0), followed by analysis of nucleotide mutation and amino acid substitution. The recombination events among DENVs were also analyzed by RDP4 package. The diversity analysis of secondary structure for translated viral proteins was also performed. The complete genome sequences of four amplified viruses (YNXJ10, YNXJ12, YNXJ13, and YNXJ16) were 10,742, 10,742, 10,741, and 10,734 nucleotides in length, and phylogenetic analysis classified the viruses as cosmopolitan genotype of DENV-2. All viruses were close to DENV Singapore 2013 (KX380828.1) and the DENV China 2013 (KF479233.1). In comparison to DENV-2SS (M29095), the total numbers of base substitutions were 712 nt (YNXJ10), 809 nt (YNXJ12), 772 nt (YNXJ13), and 841 nt (YNXJ16), resulting in 109, 171, 130, and 180 amino acid substitutions in translated regions, respectively. In addition, compared with KX380828.1, there were 44, 105, 64, and 116 amino acid substitutions in translated regions, respectively. The highest mutation rate occurred in the prM region, and the lowest mutation rate occurred in the NS4B region. Most of the recombination events occurred in the prM, E and NS2B/3 regions, which corresponded with the mutation frequency of the related portion. Secondary structure prediction within the 3,391 amino acids of DENV structural proteins showed there were 7 new possible nucleotide-binding sites and 6 lost sites compared to DENV-2SS. In addition, 41 distinct amino acid changes were found in the helix regions, although the distribution of the exposed and buried regions changed only slightly. Our findings may help to understand the intrinsic geographical relatedness of DENV-2 and contributes to the understanding of viral evolution and its impact on the epidemic potential and pathogenicity of DENV.

Complete Genome Characterization of the 2017 Dengue Outbreak in Xishuangbanna, a Border City of China, Burma and Laos.

A dengue outbreak abruptly occurred at the border of China, Myanmar, and Laos in June 2017. By November 3rd 2017, 1184 infected individuals were confirmed as NS1-positivein Xishuangbanna, a city located at the border. To verify the causative agent, complete genome information was obtained through PCR and sequencing based on the viral RNAs extracted from patient samples. Phylogenetic trees were constructed by the maximum likelihood method (MEGA 6.0). Nucleotide and amino acid substitutions were analyzed by BioEdit, followed by RNA secondary structure prediction of untranslated regions (UTRs) and protein secondary structure prediction in coding sequences (CDSs). Strains YN2, YN17741, and YN176272 were isolated from local residents. Stains MY21 and MY22 were isolated from Burmese travelers. The complete genome sequences of the five isolates were 10,735 nucleotides in length. Phylogenetic analysis classified all five isolates as genotype I of DENV-1, while isolates of local residents and Burmese travelers belonged to different branches. The three locally isolates were most similar to the Dongguan strain in 2011, and the other two isolates from Burmese travelers were most similar to the Laos strain in 2008. Twenty-four amino acid substitutions were important in eight evolutionary tree branches. Comparison with DENV-1SS revealed 658 base substitutions in the local isolates, except for two mutations exclusive to YN17741, resulting in 87 synonymous mutations. Compared with the local isolates, 52 amino acid mutations occurred in the CDS of two isolates from Burmese travelers. Comparing MY21 with MY22, 17 amino acid mutations were observed, all these mutations occurred in the CDS of non-structured proteins (two in NS1, 10 in NS2, two in NS3, three in NS5). Secondary structure prediction revealed 46 changes in the potential nucleotide and protein binding sites of the CDSs in local isolates. RNA secondary structure prediction also showed base changes in the 3'UTR of local isolates, leading to two significant changes in the RNA secondary structure. To our knowledge, this study is the first complete genome analysis of isolates from the 2017 dengue outbreak that occurred at the border areas of China, Burma, and Laos.

Complete genome analysis of dengue virus type 3 isolated from the 2013 dengue outbreak in Yunnan, China.

In the past few decades, dengue has spread rapidly and is an emerging disease in China. An unexpected dengue outbreak occurred in Xishuangbanna, Yunnan, China, resulting in 1331 patients in 2013. In order to obtain the complete genome information and perform mutation and evolutionary analysis of causative agent related to this largest outbreak of dengue fever. The viruses were isolated by cell culture and evaluated by genome sequence analysis. Phylogenetic trees were then constructed by Neighbor-Joining methods (MEGA6.0), followed by analysis of nucleotide mutation and amino acid substitution. The analysis of the diversity of secondary structure for E and NS1 protein were also performed. Then selection pressures acting on the coding sequences were estimated by PAML software. The complete genome sequences of two isolated strains (YNSW1, YNSW2) were 10,710 and 10,702 nucleotides in length, respectively. Phylogenetic analysis revealed both strain were classified as genotype II of DENV-3. The results indicated that both isolated strains of Xishuangbanna in 2013 and Laos 2013 stains (KF816161.1, KF816158.1, LC147061.1, LC147059.1, KF816162.1) were most similar to Bangladesh (AY496873.2) in 2002. After comparing with the DENV-3SS (H87) 62 amino acid substitutions were identified in translated regions, and 38 amino acid substitutions were identified in translated regions compared with DENV-3 genotype II stains Bangladesh (AY496873.2). 27(YNSW1) or 28(YNSW2) single nucleotide changes were observed in structural protein sequences with 7(YNSW1) or 8(YNSW2) non-synonymous mutations compared with AY496873.2. Of them, 4 non-synonymous mutations were identified in E protein sequences with (2 in the ß-sheet, 2 in the coil). Meanwhile, 117(YNSW1) or 115 (YNSW2) single nucleotide changes were observed in non-structural protein sequences with 31(YNSW1) or 30 (YNSW2) non-synonymous mutations. Particularly, 14 single nucleotide changes were observed in NS1 sequences with 4/14 non-synonymous substitutions (4 in the coil). Selection pressure analysis revealed no positive selection in the amino acid sites of the genes encoding for structural and non-structural proteins. This study may help understand the intrinsic geographical relatedness of dengue virus 3 and contributes further to research on their infectivity, pathogenicity and vaccine development.

Molecular Characterization and Viral Origin of the 2015 Dengue Outbreak in Xishuangbanna, Yunnan, China.

A total of 1067 serum samples were collected from febrile patients in Xishuangbanna, Yunnan, 2015. Of these, 852 cases were confirmed to be dengue NS1-positive. 76 structural protein genes were sequenced through RT-PCR based on the viral RNAs extracted from serum samples. Phylogenetic analysis revealed that all strains were classified as cosmopolitan genotype of DENV-2. After comparing with the DENV-2SS, 173 base substitutions were found in 76 sequences, resulting in 43 nonsynonymous mutations, of which 22 mutations existed among all samples. According to secondary structure prediction, 8 new possible nucelotide/protein binding sites were found and another 4 sites were lost among the 775 amino acids of DENV structural proteins as compared with DENV-2SS. Meanwhile, 6 distinct amino acid changes were found in the helix and strand regions, and the distribution of the exposed and buried regions was slightly altered. The results indicated that the epidemic dengue strains of Xishuangbanna in 2015 are most similar to the Indian strain in 2001 and the Sri Lankan strain in 2004. Moreover, it also show a very strong similarity to the epidemic strains of Fujian province in 1999 and 2010, which show that there is an internal recycling epidemic trend of DENV in China.

Severe dengue outbreak in Yunnan, China, 2013.

In recent decades, the impact of dengue has increased both geographically and in intensity, and this disease is now a threat to approximately half of the world's population. An unexpected large outbreak of dengue fever was reported in Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China, in 2013. This was the first autochthonous outbreak with a significant proportion of severe dengue cases in mainland China in a decade. According to the 2009 World Health Organization guidelines, half of the 136 laboratory confirmed cases during the epidemic were severe dengue. The clinical presentation included severe haemorrhage (such as massive vaginal and gastrointestinal bleeding), severe plasma leakage (such as pleural effusion, ascites, or hypoproteinaemia), and organ involvement (such as myocarditis and lung impairment); 21 cases eventually deteriorated to shock. During this outbreak, all severe cases occurred in adults, among whom about 43% had co-morbid conditions. Nucleic acid detection and virus isolation confirmed dengue virus serotype 3 (DENV-3) to be the pathogenic agent of this outbreak. Phylogenetic analyses of envelope gene sequences showed that these DENV-3 isolates belonged to genotype II. This finding is of great importance to understand the circulation of DENV and predict the risk of severe disease in mainland China. Here, we provide a brief report of the epidemiology, clinical manifestations, and aetiology of this dengue fever outbreak, and characterize DENV strains isolated from clinical specimens.