Dengue Virus RNA Research Articles

The Autophagosomes Containing Dengue Virus Proteins and Full-Length Genomic RNA Are Infectious.

Autophagic machinery is involved in selective and non-selective recruitment as well as degradation or exocytosis of cargoes, including pathogens. Dengue virus (DENV) infection induces autophagy that enhances virus replication and vesicle release to evade immune system surveillance. This study reveals that DENV2 induces autophagy in lung and liver cancer cells and showed that DENV2 capsid, envelope, NS1, NS3, NS4B and host cell proinflammatory high mobility group box 1 (HMGB1) proteins associated with autophagosomes which were purified by gradient centrifugation. Capsid, NS1 and NS3 proteins showing high colocalization with LC3 protein in the cytoplasm of the infected cells were detected in the purified double-membrane autophagosome by immunogold labeling under transmission electron microscopy. In DENV infected cells, the levels of capsid, envelope, NS1 and HMGB1 proteins are not significantly changed compared to the dramatic accumulation of LC3-II and p62/SQSTM1 proteins when autophagic degradation was blocked by chloroquine, indicating that these proteins are not regulated by autophagic degradation machinery. We further demonstrated that purified autophagosomes were infectious when co-cultured with uninfected cells. Notably, these infectious autophagosomes contain DENV2 proteins, negative-strand and full-length genomic RNAs, but no viral particles. It is possible that the infectivity of the autophagosome originates from the full-length DENV RNA. Moreover, we reveal that DENV2 promotes HMGB1 exocytosis partially through secretory autophagy. In conclusion, we are the first to report that DENV2-induced double-membrane autophagosomes containing viral proteins and full-length RNAs are infectious and not undergoing autophagic degradation. Our novel finding warrants further validation of whether these intracellular vesicles undergo exocytosis to become infectious autophagic vesicles.

Persistence of Dengue (Serotypes 2 and 3), Zika, Yellow Fever, and Murine Hepatitis Virus RNA in Untreated Wastewater

Persistence of Dengue (Serotypes 2 and 3), Zika, Yellow Fever, and Murine Hepatitis Virus RNA in Untreated Wastewater

Infant Dengue a 10-Year Experience from a Tertiary Center in South India.

Dengue remains a major problem in the tropics. Several Asian countries have reported an increasing trend in the proportion of infants with dengue fever. However, most studies are limited to case reports or small case series from isolated outbreaks. We planned this study to look at clinico-laboratory profile, outcome, and predictors of severity in a large cohort of infants over a decade. Electronic medical records of infants admitted at a tertiary center of South India, with laboratory confirmed dengue infection between 2009 and 2019 were reviewed. Diagnosis was based on detection of NS-1 antigen and/or immunoglobulin M antibody against DENV(dengue virus) or positive DENV RNA polymerase chain reaction in infants presenting with acute febrile illness and clinical features consistent with dengue. Of 395 children with dengue admitted during study period, 99 (25%) were infants. A cyclical incidence pattern was noted, with higher cases in alternate years. Fever (99%) was most common, followed by gastrointestinal symptoms (vomiting, diarrhea-28%) and upper respiratory symptoms (cough, coryza-22%). Fifty-three infants had severe dengue, and 39 had shock. Fourteen children had multiorgan dysfunction syndrome, and 13 died. Infants with severe dengue were older than those with nonsevere disease, had lower serum albumin and greater frequency of severe thrombocytopenia, and had coagulopathy. On multivariable analysis, low serum albumin predicted development of severe dengue [P = 0.003, odds ratio 12.4 (95% confidence interval: 2.42-63.7)]. Dengue in infants may be challenging to recognize because of its undifferentiated presentation, with gastrointestinal and upper respiratory symptoms that are similar to other viral illness. Severe dengue is common in this sample, and lower serum albumin at presentation was predictive of severe disease.

In-silico approaches towards the profiling of some anti-dengue virus as potent inhibitors against dengue NS-5 receptor

Flaviviruses are essential human pathogens including the dengue virus, though there is no effective antiviral drug for the treatment of the viral infections caused by these organisms currently. The NS-5 protease which is much conserved across the family of the flavivirus and necessary for viral replication represents a druggable target. The inhibition of dengue protease has been considered to be a druggable target for the treatment of dengue virus infection. The present study employed cheminformatics modeling, molecular docking analysis, and ADME (absorption, distribution, metabolism, excretion) prediction approach on some potent inhibitors of dengue viral RNA-Dependent RNA polymerase. A statistically valid quantitative structure-activity relationship (Q-SAR) model was developed. The model was validated on an independent external test set and has demonstrated statistically satisfactory performance (R2train= 0.9717, R2test = 0.80235, and cR2p= 0.8824) which proved that the built model was good, robust, reliable, and stable. Also, five molecular descriptors (MATS5c, MATS2m, GATS4c, VE1_Dzv, and ZMIC1) were shown to be meaningfully correlated with the dengue virus inhibitory activity of these compounds. The molecular docking calculations revealed the significant interactions between the amino acid residues of the active sites of the receptor with the ligands. The selected compounds (15, 28, and 29) were found to possess significant binding affinity values of -7.3, -7.7, and -8.3 kcal/mol respectively, with compound 29 having a better binding affinity better than fenretinide and S-adenosyl-L-homocysteine (SAH) with a binding affinity of -8.0 and -6.9 kcal/mol as well as low RMSD value. All the selected compounds obeyed Lipinski's rule of 5, thus entailing oral bioavailability and pharmacological activeness. The ADME predictions showed that all the selected compounds including fenretinide were inhibitors of CYP2D6 except compound 15, and non-inhibitors of CYP3A4 and cytochrome P450 enzymes with attributes of good gastrointestinal (GI) absorption, with compound 15 having excellent gastrointestinal (GI) absorption. As a consequence, the approach employed in this study and the obtained information could serve as a reliable framework to further design novel anti-dengue inhibitors.

Evaluation of VIDAS® Diagnostic Assay Prototypes Detecting Dengue Virus NS1 Antigen and Anti-Dengue Virus IgM and IgG Antibodies.

Dengue is a serious tropical disease caused by the mosquito-borne dengue virus (DENV). Performant, rapid, and easy-to-use assays are needed for the accurate diagnosis of acute DENV infection. We evaluated the performance of three prototype assays developed for the VIDAS® automated platform to detect dengue NS1 antigen and anti-dengue IgM and IgG antibodies. Positive and negative agreement with competitor enzyme-linked immunosorbent assays (ELISA) and rapid diagnostic tests (RDT) was evaluated in 91 Lao patients (57 adults, 34 children) with acute DENV infection. The VIDAS® NS1 assay showed the best overall agreement (95.6%) with the competitor NS1 ELISA. Both VIDAS® NS1 and NS1 ELISA assays also demonstrated high sensitivity relative to DENV RNA RT-PCR set as gold standard (85.7% and 83.9%, respectively). In contrast, NS1 RDT was less sensitive relative to DENV RNA RT-PCR (72.7%). The overall agreement of VIDAS® IgM and IgG assays with the competitor assays was moderate (72.5% for IgM ELISA, 76.9% for IgG ELISA, and 68.7% for IgM and IgG RDT). In most analyses, test agreements of the VIDAS® assays were comparable in adults and children. Altogether, the VIDAS® dengue prototypes performed very well and appear to be suitable for routine detection of dengue NS1 antigen and anti-dengue IgM/IgG antibodies.

Neurological manifestations due to dengue virus infection in children: clinical follow-up

ABSTRACT The aim was to assess neurological complications in children with an invasive neurological disease by dengue virus (DENV) and the time to resolve symptoms after hospital discharge. A prospective study was conducted at a referral hospital for infectious diseases in Brazil between March 2014 and July 2019. All children hospitalized with neurologic manifestations and DENV RNA detected by real-time reverse transcription-polymerase chain reaction (RT-qPCR) in cerebrospinal fluid (CSF) were followed up until complete resolution of neurological complications. On average, they were followed up for 16 months. Among 56 DENV-positive children, 39% had some neurologic complications after hospital discharge and found that 19.6% were discharged with anticonvulsants due to seizures, 10.7% developed motor complications (e.g. muscle weakness, paresis, ataxia, and walking disability), 5.4% had headaches, and 14.3% had sleep disorders. Among the 56 children, only three had a clinical diagnosis of dengue because the symptoms are nonspecific and 35% showed no change in cerebrospinal fluid (CSF). The average time to resolve complications was 5.9 months (ranging from 1 m to 32 m). These results should alert physicians to the difficulties of a clinical diagnosis of an infection that causes neurological complications after discharge in a significant number of children. RT-qPCR’s etiological diagnosis of DENV infection enabled better clinical follow-up for early intervention in children with neurological complications.

Dengue virus induces interferon-β by activating RNA sensing pathways in megakaryocytes

Activation of innate receptors in megakaryocytes (MKs) may affect the ability to produce functional platelets. Low platelet count is one of the clinical manifestations of dengue virus (DENV) infection. In MKs, the effect of innate receptors during DENV-infection is not well studied. Here we used MEG-01 cells to investigate DENV serotype 2 induced innate receptors in these cells. DENV RNA was estimated by qRT-PCR in the culture supernatant. The expression of innate receptors was determined by western blot and qPCR. DENV infection led to increased expression of RIG-I at 24 hrs post-infection (hpi) and MDA-5 at 48 and 72 hpi (p<0.05). However, no change in the expression of TLR3 at protein level was observed. Activation of MDA-5 resulted in increased expression of IFN-β and ISG-15 in DENV infected MEG-01 cells, which was further confirmed by MDA-5 siRNA treatment. Apart from inducing innate receptors, DENV significantly decreases the expression of CD61, an activation marker of megakaryocyteson MEG-01 cells as observed by flow cytometry analysis (p<0.01). Results from this study confirm that DENV infection activates the type-I interferon in megakaryocytes and may play a significant role in maturation and development.

Dengue Virus Infection in Sub-Saharan Africa Between 2010 and 2020: A Systematic Review and Meta-Analysis.

Dengue virus (DENV) infection has garnered a global interest in the past few decades. Nevertheless, its epidemiology in certain developing and low-income regions remains poorly understood, due to the absence of comprehensive surveillance and reporting systems. This systematic review and meta-analysis aimed to determine the prevalence of DENV infection in the population of Sub-Saharan Africa using DENV infection markers, and to track any changes in its prevalence during the past ten years. It was conducted in accordance with the PRISMA guidelines, targeting the literature available at MEDLINE/PubMed, ScienceDirect, Cochrane library and Google Scholar. All articles published in English language between January 2010 and June 2020 were screened for eligibility. Random effects model was used to calculate the pooled prevalence of all infection markers. The Inconsistency Index (I 2) was used to assess the level of heterogeneity between studies. Subgroup analysis according to country and time-frame of studies was conducted to provide possible explanations to substantial heterogeneity. The critical appraisal tool for prevalence studies designed by the Joanna Briggs Institute (JBI) was used to assess the risk of bias in all included studies. A total of 84 articles, covering 21 countries, were included in this review. Quantitative meta-analysis estimated a pooled IgG prevalence of 25% (95% CI: 21-29%, I 2 = 99%), a pooled IgM prevalence of 10% (95% CI: 9-11%, I 2 = 98%) and a pooled DENV RNA prevalence of 14% (95% CI: 12-16%, I 2 = 99%). Evidence for possible publication bias was also found in all three meta-analyses. Subgroup analysis according to the time of sample collection was performed to closely track the changing prevalence of DENV infection markers between 2010 and 2019. This meta-analysis estimates a high prevalence of DENV infection in Sub-Saharan Africa. More cost-efficient vector control strategies should be designed and implemented in order to adapt to the low-resource nature of this region.

Cordycepin Inhibits Virus Replication in Dengue Virus-Infected Vero Cells.

Dengue virus (DENV) infection causes mild to severe illness in humans that can lead to fatality in severe cases. Currently, no specific drug is available for the treatment of DENV infection. Thus, the development of an anti-DENV drug is urgently required. Cordycepin (3′-deoxyadenosine), which is a major bioactive compound in Cordyceps (ascomycete) fungus that has been used for centuries in Chinese traditional medicine, was reported to exhibit antiviral activity. However, the anti-DENV activity of cordycepin is unknown. We hypothesized that cordycepin exerts anti-DENV activity and that, as an adenosine derivative, it inhibits DENV replication. To test this hypothesis, we investigated the anti-DENV activity of cordycepin in DENV-infected Vero cells. Cordycepin treatment significantly decreased DENV protein at a half-maximal effective concentration (EC50) of 26.94 μM. Moreover, DENV RNA was dramatically decreased in cordycepin-treated Vero cells, indicating its effectiveness in inhibiting viral RNA replication. Via in silico molecular docking, the binding of cordycepin to DENV non-structural protein 5 (NS5), which is an important enzyme for RNA synthesis, at both the methyltransferase (MTase) and RNA-dependent RNA polymerase (RdRp) domains, was predicted. The results of this study demonstrate that cordycepin is able to inhibit DENV replication, which portends its potential as an anti-dengue therapy.

(E)-Guggulsterone Inhibits Dengue Virus Replication by Upregulating Antiviral Interferon Responses through the Induction of Heme Oxygenase-1 Expression.

Dengue virus (DENV) infection, which causes dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is a severe global health problem in tropical and subtropical areas. There is no effective vaccine or drug against DENV infection. Thus, the development of anti-DENV agents is imperative. This study aimed to assess the anti-DENV activity of (E)-guggulsterone using a DENV infectious system. A specific inhibitor targeting signal molecules was used to evaluate the molecular mechanisms of action. Western blotting and qRT-PCR were used to determine DENV protein expression and RNA replication, respectively. Finally, an ICR suckling mouse model was used to examine the anti-DENV activity of (E)-guggulsterone in vivo. A dose-dependent inhibitory effect of (E)-guggulsterone on DENV protein synthesis and RNA replication without cytotoxicity was observed. The mechanistic studied revealed that (E)-guggulsterone stimulates Nrf2-mediated heme oxygenase-1 (HO-1) expression, which increases the antiviral interferon responses and downstream antiviral gene expression by blocking DENV NS2B/3B protease activity. Moreover, (E)-guggulsterone protected ICR suckling mice from life-threatening DENV infection. These results suggest that (E)-guggulsterone can be a potential supplement for controlling DENV replication.

Systemic dengue infection associated with a new dengue virus type 2 introduction in Brazil \u2013 a case report

BackgroundDengue infection is caused by an arbovirus with a wide range of presentations, varying from asymptomatic disease to unspecific febrile illness and haemorrhagic syndrome with shock, which can evolve to death. In Brazil, the virus circulates since the 1980s with many introductions of new serotypes, genotypes, and lineages since then. Here we report a fatal case of dengue associated with a Dengue virus (DENV) lineage not detected in the country until now.Case presentationThe patient, a 58-year-old man arrived at the hospital complaining of fever and severe abdominal pain due to intense gallbladder edema, mimicking acute abdomen. After 48 h of hospital admission, he evolved to refractory shock and death. DENV RNA was detected in all tissues collected (heart, lung, brain, kidney, spleen, pancreas, liver, and testis). Viral sequencing has shown that the virus belongs to serotype 2, American/Asian genotype, in a new clade, which has never been identified in Brazil before. The virus was phylogenetically related to isolates from central America [Puerto Rico (2005–2007), Martinique (2005), and Guadeloupe (2006)], most likely arriving in Brazil from Puerto Rico.ConclusionIn summary, this was the first fatal documented case with systemic dengue infection associated with the new introduction of Dengue type 2 virus in Brazil during the 2019 outbreak.

Diagnostic Performance of a Magnetic Field-Enhanced Agglutination Readout in Detecting Either Viral Genomes or Host Antibodies in Arbovirus Infection.

Arbovirus diagnostics on blood from donors and travelers returning from endemic areas is increasingly important for better patient management and epidemiological surveillance. We developed a flexible approach based on a magnetic field-enhanced agglutination (MFEA) readout to detect either genomes or host-derived antibodies. Dengue viruses (DENVs) were selected as models. For genome detection, a pan-flavivirus amplification was performed before capture of biotinylated amplicons between magnetic nanoparticles (MNPs) grafted with DENV probes and anti-biotin antibodies. Magnetization cycles accelerated this chaining process to within 5 min while simple turbidimetry measured the signal. This molecular MFEA readout was evaluated on 43 DENV RNA(+) and 32 DENV RNA(−) samples previously screened by real-time RT-PCR. The sensitivity and the specificity were 88.37% (95% CI, 78.76%–97.95%) and 96.87% (95% CI, 90.84%–100%), respectively. For anti-DENV antibody detection, 103 plasma samples from donors were first screened using ELISA assays. An immunological MFEA readout was then performed by adding MNPs grafted with viral antigens to the samples. Anti-DENV antibodies were detected with a sensitivity and specificity of 90.62% (95% CI, 83.50%–97.76%) and 97.44% (95% CI, 92.48%–100%), respectively. This adaptable approach offers flexibility to platforms dedicated to the screening of emerging infections.

Sensitive and Prolonged Detection of Dengue Virus RNA in Whole Blood.

Molecular detection of dengue virus (DENV) RNA from serum or plasma provides an accurate acute-phase diagnostic (< 7 days after symptom onset). Detection may be prolonged in whole blood, although data are limited. We tested for DENV by real-time reverse transcription-PCR in 345 paired acute-phase plasma and whole blood samples from individuals with a Flavivirus-like illness in southwestern Guatemala. In 18/18 cases with detectable DENV RNA in plasma, whole blood samples were positive and yielded similar cycle threshold values. In seven individuals with convalescent samples obtained 2-3 weeks later, DENV RNA remained detectable in whole blood but not plasma. In three additional cases, DENV RNA was only detectable in whole blood at the acute visit. In two cases, whole blood detection was linked to a virologically confirmed DENV infection 6-11 weeks earlier. Whole blood DENV RNA detection is sensitive for acute dengue infection and may remain positive for weeks to months.

Dengue Virus is Hyperendemic in Nigeria from 2009 to 2020: A Contemporary Systematic Review.

BackroundData on Dengue virus (DENV) infection prevalence, geographic distribution and risk factors are necessary to direct appropriate utilization of existing and emerging control strategies. This study aimed to determine the pooled prevalence, risk factors of DENV infection and the circulating serotypes within Nigeria from January 1, 2009 to December 31, 2020.Materials and methodsTwenty-one studies out of 2,215 available articles were eligible and included for this systematic review. Relevant articles were searched, screened and included in this study according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria. The risk of bias in primary studies was assessed by Cochrane's method. Heterogeneity of pooled prevalence was calculated using the chi-square test on Cochrane's Q statistic, which was quantified by I-square values. The random-effects analyses of proportions were used to determine the pooled prevalence of DENV antibodies, antigen and RNA from eligible studies.ResultsOf these, 3 studies reported co-circulation of all the 4 serotypes, while 2 separately reported co-circulation of DENV-1 &2 and DENV-1 to -3. All the antibody-based studies had significantly high heterogeneity (I2 >90%, P <0.05), while the NS1 and PCR-based studies had low heterogeneity (I2 <25%, P >0.05). The pooled prevalence of DENV IgM, IgG, RNA, NS1 and neutralizing antibodies were 16.8%, 34.7%, 7.7%, 7.7% and 0.7%, respectively. South-east Nigeria had the highest pooled DENV-IgG seropositivity, 77.1%. Marital status, gender, educational level and occupation status, the proximity of residence to refuse dumpsite, frequent use of trousers and long sleeve shirts were significantly associated with DENV IgG seropositivity (P <0.05).ConclusionBased on these findings, it can be inferred that Nigeria is hyperendemic for Dengue fever and needs concerted efforts to control its spread within and outside the country.

Epidemiological and virus molecular characterization of dengue fever outbreak in Hunan province, 2018

Objective: To analyze the epidemiological and etiological characteristics of a dengue fever outbreak in Hunan province in 2018. Methods: Real-time PCR assay was performed for the laboratory diagnosis of 8 suspected dengue fever cases. Etiological surveillance was performed in 186 suspected dengue fever cases and fever cases who had close contacts with dengue fever patients. C6/36 cells was used for the virus isolation from acute phase serum. By sequencing the full length of E genes of 15 dengue virus strains, phylogenetic analysis was performed based on the sequences obtained, including reference sequences from the NCBI GenBank database, the serotypes and gene subtypes of the virus were analyzed to trace the possible source of transmission. An emergency monitoring of vector density and a retrospective survey of sero-epidemiology in healthy population were conducted in the epidemic area. Results: In the serum samples of 8 suspected patients, 6 were dengue virus RNA positive, and 4 were NS1 antigen positive. In 186 suspected patients, 96 were dengue virus nucleic acid, NS1 antigen or antibody positive in etiological test. A total of 64 dengue virus strains were isolated. The phylogenetic analysis showed that all the dengue virus strains belonged to type 2, which might be from Guangdong or Zhejiang provinces. The Bretub index was up to 65, indicating an extremely high risk of transmission. The positive rate of the dengue virus IgG antibody was 0.53%(2/377) in retrospective survey of 377 healthy people. Conclusion: The field epidemiologic and the molecular genetics analyses showed the outbreak of dengue fever in Hunan in 2018 was caused by imported cases and dengue virus 2.

Use of whole blood over plasma enhances the detection of dengue virus RNA: possible utility in dengue vaccine trials.

In the present study, the utility of viral RNA isolated from whole blood over plasma for detection of dengue virus (DENV) was investigated in 80 samples referred for serotyping by DENV serotype-specific one-step real-time RT-PCR. DENV RNA was detected in 71.25% of the whole blood samples compared to 46.25% in the corresponding plasma samples. In secondary infections, DENV RNA was detected in 83.3% of whole blood samples, while it was detected in 40.5% of plasma samples (P = 0.0001). Non-structural protein 1 (NS1) antigen was detected in only 54.8% of the secondary infections. The detection rate of DENV RNA in whole blood is higher than in plasma. We suggest that one-step real-time RT-PCR using RNA from whole blood combined with an NS1 ELISA should be the choice for dengue diagnosis in dengue vaccine trials.

A Step towards Treating Dengue Viral Infection: An In Silico Approach to Identify Potential Antidengue Phytoconstituents

AbstractDengue is one of the deadliest mosquito‐borne viral diseases. Since its inception, a lot of research has happened in various directions, still no effective antiviral drug is available to combat its serious consequences. Though symptomatic medicines are available, they have not been proven scientifically and hence, there is an urge to adopt new strategies in the development of effective drugs against dengue. In the present study, we computationally screened the phytoconstituents from Carica papaya, Andrographis paniculata and Azadirachta indica against dengue virus multi‐targets, viz. dengue viral proteases, dengue viral envelope proteins, and dengue viral RNA dependent RNA polymerase via in silico docking study followed by Molecular Mechanics‐Generalized Born and Surface Area using Schrödinger‐Maestro version 12.0.012 to estimate the protein‐ligand binding affinities. The phytoconstituents showing significant docking score, binding interaction, and binding affinity compared to reported anti‐virals were finalized. This study can serve as a lead for the treatment of dengue infection by identifying the potential candidate(s).

Two RNA Tunnel Inhibitors Bind in Highly Conserved Sites in Dengue Virus NS5 Polymerase: Structural and Functional Studies.

Dengue virus (DENV) NS5 RNA-dependent RNA polymerase (RdRp), an important drug target, synthesizes viral RNA and is essential for viral replication. While a number of allosteric inhibitors have been reported for hepatitis C virus RdRp, few have been described for DENV RdRp. Following a diverse compound screening campaign and a rigorous hit-to-lead flowchart combining biochemical and biophysical approaches, two DENV RdRp nonnucleoside inhibitors were identified and characterized. These inhibitors show low- to high-micromolar inhibition in DENV RNA polymerization and cell-based assays. X-ray crystallography reveals that they bind in the enzyme RNA template tunnel. One compound (NITD-434) induced an allosteric pocket at the junction of the fingers and palm subdomains by displacing residue V603 in motif B. Binding of another compound (NITD-640) ordered the fingers loop preceding the F motif, close to the RNA template entrance. Most of the amino acid residues that interacted with these compounds are highly conserved in flaviviruses. Both sites are important for polymerase de novo initiation and elongation activities and essential for viral replication. This work provides evidence that the RNA tunnel in DENV RdRp offers interesting target sites for inhibition.IMPORTANCE Dengue virus (DENV), an important arthropod-transmitted human pathogen that causes a spectrum of diseases, has spread dramatically worldwide in recent years. Despite extensive efforts, the only commercial vaccine does not provide adequate protection to naive individuals. DENV NS5 polymerase is a promising drug target, as exemplified by the development of successful commercial drugs against hepatitis C virus (HCV) polymerase and HIV-1 reverse transcriptase. High-throughput screening of compound libraries against this enzyme enabled the discovery of inhibitors that induced binding sites in the RNA template channel. Characterizations by biochemical, biophysical, and reverse genetics approaches provide a better understanding of the biological relevance of these allosteric sites and the way forward to design more-potent inhibitors.

Dengue RNA detection and seroprevalence in blood donors during an outbreak in the São Paulo State, Brazil, 2016.

Most dengue virus (DENV) infections remain asymptomatic. This increases the risk of DENV transfusion transmission (TT-DENV) during outbreaks. We evaluated DENV viremia in 8475 blood donations assembled in minipools for the presence of DENV RNA. The tested samples were obtained between February and May, 2016, during a large DENV outbreak in Ribeirão Preto city, northeast region of the São Paulo State, Brazil. The DENV RNA + samples were serotyped and screened for DENV NS1. We also tested a significant number of plasma samples (n = 372) to estimate the DENV seroprevalence among blood donors in the region. We detected three DENV RNA + samples in the tested blood donations (n = 3/8475, 0.04%). From these, two samples were further serotyped as DENV-1 and one sample as DENV-2. All DENV RNA positive samples were negative for anti-DENV IgG, indicating the presence of primary acute infection. Moreover, two of the DENV RNA + samples were also NS1 antigen positive (antigenemia). The anti-DENV IgG seroprevalence among blood donor population was 50.8% (n = 189/372). Our results are in accordance with the presence of DENV primary infection in blood donors which can lead to transfusion transmission of the infection to recipients. Measures to exclude such donors should be adopted to prevent TT-DENV.

Dengue viremia kinetics in asymptomatic and symptomatic infection

BackgroundDengue infection is a global health threat. While symptomatic cases contribute to morbidity and mortality, the majority of infected people are asymptomatic but serve as an important reservoir. However, the kinetics of viremia in asymptomatic infections remains unknown. MethodsWe enrolled 279 hospital-based symptomatic index cases and quantified dengue virus (DENV) RNA at enrollment and at the day of defervescence. To identify asymptomatic cases, 175 household members of index cases were monitored for clinical symptoms during follow-up, and blood was taken twice weekly to test for and quantify DENV RNA until cleared. ResultsWe detected DENV in thirteen asymptomatic household members (7.43%). Their DENV serotypes were primarily the same as those of their family index cases. The median peak DENV viremia in asymptomatic subjects was lower than that of symptomatic individuals during the febrile phase, and the viral decay rate was slower in asymptomatic infections. ConclusionsDENV level and kinetics in asymptomatic individuals differed significantly from those of symptomatic cases. Despite the lower viremia, the slower decay rate in asymptomatic infections could lead to their prolonging the infectious reservoir. The improvement of transmission control to prevent such long-lived asymptomatic infections from transmitting the DENV is needed.