SciCombinator

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Concept: Viral diseases

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BACKGROUND: The genus Flavivirus includes several pathogenic agents that cause severe illness in humans. Re-emergence of West Nile virus in Europe and continuous spread of certain flaviviruses such as dengue, yellow fever and Japanese encephalitis viruses represent a global danger to public health. Therefore, a rapid and accurate molecular method is required for diagnostics and epidemiological surveillance of flaviviruses. METHODS: A Pan-Flavi quantitative RT-PCR assay using a Locked-Nucleic Acid probe targeting the flavivirus NS5 gene was developed and optimized to detect a wide range of flaviviruses simultaneously. The specificity and sensitivity of the Pan-Flavi assay were tested using RNA of different flaviviruses and non-flaviviruses. Furthermore, the assay was compared directly to flavivirus species-specific assays for the ability to detect flaviviruses sensitively. RESULTS: Two degenerate primers and one Locked-Nucleic Acids probe were designed to amplify most of the flaviviruses. To increase the specificity and fluorescence signal of the Pan-Flavi assay for detection of yellow fever virus and dengue virus 4, additional primers and probes were included. Viral RNA of thirty different flaviviruses was detected, verifying the broad range specificity. The testing of this assay was successful, using standard plasmid and RNA dilutions of yellow fever virus vaccine strain, dengue virus 1 and tick-borne encephalitis virus, with a sensitivity limit of 10–100 genome copies/reaction. Also comparatively good results were achieved for detecting different flaviviruses by the Pan-Flavi assay when compared to the flavivirus species-specific assays. CONCLUSION: The assay is rapid, broad-range flavivirus-specific and highly sensitive making it a valuable tool for rapid detection of flaviviruses in livestock samples, epidemiological studies or as useful complement to single flavivirus-specific assays for clinical diagnosis.

Concepts: Malaria, Ribavirin, Viral diseases, Encephalitis, West Nile virus, Flavivirus, Flaviviridae, Flaviviruses

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We report unbiased metagenomic detection of chikungunya virus (CHIKV), Ebola virus (EBOV), and hepatitis C virus (HCV) from four human blood samples by MinION nanopore sequencing coupled to a newly developed, web-based pipeline for real-time bioinformatics analysis on a computational server or laptop (MetaPORE). At titers ranging from 10(7)-10(8) copies per milliliter, reads to EBOV from two patients with acute hemorrhagic fever and CHIKV from an asymptomatic blood donor were detected within 4 to 10 min of data acquisition, while lower titer HCV virus (1 × 10(5) copies per milliliter) was detected within 40 min. Analysis of mapped nanopore reads alone, despite an average individual error rate of 24 % (range 8-49 %), permitted identification of the correct viral strain in all four isolates, and 90 % of the genome of CHIKV was recovered with 97-99 % accuracy. Using nanopore sequencing, metagenomic detection of viral pathogens directly from clinical samples was performed within an unprecedented <6 hr sample-to-answer turnaround time, and in a timeframe amenable to actionable clinical and public health diagnostics.

Concepts: Blood, Microbiology, Virus, Hepatitis C, Chikungunya, Viral diseases, Ebola, Viral hemorrhagic fever

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Sierra Leone in West Africa is in a Lassa fever-hyperendemic region that also includes Guinea and Liberia. Each year, suspected Lassa fever cases result in submission of ≈500-700 samples to the Kenema Government Hospital Lassa Diagnostic Laboratory in eastern Sierra Leone. Generally only 30%-40% of samples tested are positive for Lassa virus (LASV) antigen and/or LASV-specific IgM; thus, 60%-70% of these patients have acute diseases of unknown origin. To investigate what other arthropod-borne and hemorrhagic fever viral diseases might cause serious illness in this region and mimic Lassa fever, we tested patient serum samples that were negative for malaria parasites and LASV. Using IgM-capture ELISAs, we evaluated samples for antibodies to arthropod-borne and other hemorrhagic fever viruses. Approximately 25% of LASV-negative patients had IgM to dengue, West Nile, yellow fever, Rift Valley fever, chikungunya, Ebola, and Marburg viruses but not to Crimean-Congo hemorrhagic fever virus.

Concepts: Malaria, Yellow fever, Ribavirin, Fever, Viral diseases, Viral hemorrhagic fever, Lassa fever, Sierra Leone

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Zika virus (ZIKV) is implicated in fetal stillbirth, microcephaly, intracranial calcifications, and ocular anomalies following vertical transmission from infected mothers. In adults, infection may trigger autoimmune inflammatory polyneuropathy. Transmission most commonly follows the bite of infectedAedesmosquitoes but may also occur through sexual intercourse or receipt of blood products. Definitive diagnosis through detection of viral RNA is possible in serum or plasma within 10 days of disease onset, in whole blood within 3 weeks of onset, and in semen for up to 3 months. Serological diagnosis is nonetheless critical because few patients have access to molecular diagnostics during the acute phase of infection and infection may be associated with only mild or inapparent disease that does not prompt molecular testing. Serological diagnosis is confounded by cross-reactivity of immune sera with other flaviviruses endemic in the areas where ZIKV has recently emerged. Accordingly, we built a high-density microarray comprising nonredundant 12-mer peptides that tile, with one-residue overlap, the proteomes of Zika, dengue, yellow fever, West Nile, Ilheus, Oropouche, and chikungunya viruses. Serological analysis enabled discovery of a ZIKV NS2B 20-residue peptide that had high sensitivity (96.0%) and specificity (95.9%) versus natural infection with or vaccination against dengue, chikungunya, yellow fever, West Nile, tick-borne encephalitis, or Japanese encephalitis virus in a microarray assay and an enzyme-linked immunosorbent assay (ELISA) of early-convalescent-phase sera (2 to 3 weeks after onset of symptomatic infection).IMPORTANCEThe emergence of Zika virus (ZIKV) as a teratogen is a profound challenge to global public health. Molecular diagnosis of infection is straightforward during the 3-week period when patients are viremic. However, serological diagnosis thereafter of historical exposure has been confounded by cross-reactivity. Using high-density peptide arrays that tile the proteomes of a selection of flaviviruses to identify a ZIKV-specific peptide, we established two assays that enable sensitive and specific diagnosis of exposure to ZIKV. These assays may be useful in guiding clinical management of mothers at risk for potential exposure to ZIKV and enable insights into the epidemiology of ZIKV infections.

Concepts: Antibody, Infection, ELISA, ELISPOT, Assay, Viral diseases, Flaviviridae, Flaviviruses

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Filoviruses are emerging pathogens and causative agents of viral haemorrhagic fever. Case fatality rates of filovirus disease outbreaks are among the highest reported for any human pathogen, exceeding 90% (ref. 1). Licensed therapeutic or vaccine products are not available to treat filovirus diseases. Candidate therapeutics previously shown to be efficacious in non-human primate disease models are based on virus-specific designs and have limited broad-spectrum antiviral potential. Here we show that BCX4430, a novel synthetic adenosine analogue, inhibits infection of distinct filoviruses in human cells. Biochemical, reporter-based and primer-extension assays indicate that BCX4430 inhibits viral RNA polymerase function, acting as a non-obligate RNA chain terminator. Post-exposure intramuscular administration of BCX4430 protects against Ebola virus and Marburg virus disease in rodent models. Most importantly, BCX4430 completely protects cynomolgus macaques from Marburg virus infection when administered as late as 48 hours after infection. In addition, BCX4430 exhibits broad-spectrum antiviral activity against numerous viruses, including bunyaviruses, arenaviruses, paramyxoviruses, coronaviruses and flaviviruses. This is the first report, to our knowledge, of non-human primate protection from filovirus disease by a synthetic drug-like small molecule. We provide additional pharmacological characterizations supporting the potential development of BCX4430 as a countermeasure against human filovirus diseases and other viral diseases representing major public health threats.

Concepts: Virus, Viral diseases, Ebola, Marburg virus, Mononegavirales, Viral hemorrhagic fever, Filoviridae, Hemorrhagic fevers

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Patients with coronary artery disease (CAD) are at high risk for reactivation of the varicella zoster virus (VZV) and development of herpes zoster (HZ). Here, we found that macrophages from patients with CAD actively suppress T cell activation and expansion, leading to defective VZV-specific T cell immunity. Monocyte-derived and plaque-infiltrating macrophages from patients with CAD spontaneously expressed high surface density of the immunoinhibitory ligand programmed death ligand-1 (PD-L1), thereby providing negative signals to programmed death-1+ (PD-1+) T cells. We determined that aberrant PD-L1 expression in patient-derived macrophages was metabolically controlled. Oversupply of the glycolytic intermediate pyruvate in mitochondria from CAD macrophages promoted expression of PD-L1 via induction of the bone morphogenetic protein 4/phosphorylated SMAD1/5/IFN regulatory factor 1 (BMP4/p-SMAD1/5/IRF1) signaling pathway. Thus, CAD macrophages respond to nutrient excess by activating the immunoinhibitory PD-1/PD-L1 checkpoint, leading to impaired T cell immunity. This finding indicates that metabolite-based immunotherapy may be a potential strategy for restoring adaptive immunity in CAD.

Concepts: Immune system, Protein, Viral diseases, Herpes zoster, Chickenpox, Postherpetic neuralgia, Varicella zoster virus, Herpesviruses

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Abstract A 69-year-old male was admitted to hospital with clouded consciousness and abnormal behavior. His body temperature was 38.2 degree Celsius upon admission and he was somnolent. Herpes zoster was observed along the first division of the trigeminal nerve on the right side of the face. The right palpebra was severely swollen, and the right eye showed a dilated pupil, loss of light reflex, and total ophthalmoplegia. A spinal tap revealed pleocytosis and increased proteins, and a DNA-PCR test for varicella-zoster virus (VZV) was positive. Optic neuritis was diagnosed based on fundoscopy. Following acyclovir administration, the patient regained full consciousness and the rash was alleviated; however, visual acuity did not recover. VZV-induced meningoencephalitis complicated with orbital apex syndrome is rarely observed. We suspect that VZV initially infected the nasociliary nerve at the distal end of the first division of trigeminal nerve and spread to the adjacent optic, oculomotor, trochlear, and abducens nerves, resulting in VZV-induced meningoencephalitis complicated with orbital apex syndrome. (Received August 5, 2013; Accepted January 22, 2014; Published September 1, 2014).

Concepts: Cranial nerves, Viral diseases, Encephalitis, Herpes zoster, Chickenpox, Postherpetic neuralgia, Varicella zoster virus, Herpesviruses

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Hepatitis C virus (HCV) is one of the main causes of liver disease and transplantation worldwide. Current therapy is expensive, presents additional side effects and viral resistance has been described. Therefore, studies for developing more efficient antivirals against HCV are needed. Compounds isolated from animal venoms have shown antiviral activity against some viruses such as Dengue virus, Yellow fever virus and Measles virus. In this study, we evaluated the effect of the complex crotoxin (CX) and its subunits crotapotin (CP) and phospholipase A2 (PLA2-CB) isolated from the venom of Crotalus durissus terrificus on HCV life cycle. Huh 7.5 cells were infected with HCVcc JFH-1 strain in the presence or absence of these toxins and virus was titrated by focus formation units assay or by qPCR. Toxins were added to the cells at different time points depending on the stage of virus life cycle to be evaluated. The results showed that treatment with PLA2-CB inhibited HCV entry and replication but no effect on HCV release was observed. CX reduced virus entry and release but not replication. By treating cells with CP, an antiviral effect was observed on HCV release, the only stage inhibited by this compound. Our data demonstrated the multiple antiviral effects of toxins from animal venoms on HCV life cycle.

Concepts: Virus, Influenza, Hepatitis C, Ribavirin, Fever, Viral diseases, Flaviviridae, Venom

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Herpes zoster is an internal reactivation of varicella zoster virus, and its onset depends on immunity against this virus. We have previously reported that antiviral antibody titers are inversely correlated with patient numbers. In this study, we hypothesized that patients with higher titers may be late visitors to the clinic, whose antibodies were already boosted at presentation because of the time lapse between onset of zoster and measurement of antibodies. We analyzed antibody titers of patients with acute herpes zoster who visited Fukuoka University Hospital from January 2009 to May 2016 (n = 141, 62 males and 79 females). Varicella zoster virus-specific immunoglobulin G, M and complement fixation tests were positive in 93.9%, 12.0% and 64.2% of the patients, respectively. Immunoglobulin G and complement fixation titers were strongly correlated (Spearman’s r = 0.8634, P < 0.0001). Patients with high immunoglobulin G and complement fixation titers were immunoglobulin M-negative. Unexpectedly, immunoglobulin G and complement fixation titers showed large inter-subject variation, and were only weakly correlated with onset-measurement time lapse. Patients with consecutive tests tended to show increasing immunoglobulin G and complement fixation titers. Our data suggest that herpes zoster preferentially occurs in patients with low immunoglobulin G and complement fixation titers, and subsequently causes antibody elevation. However, the timing of elevation varies and can be as late as 10 days after zoster. The large variation in antibody titer over the time from onset to testing suggests that some mechanism exists that resists the local breakthrough of virus in the skin, and so delays the onset of blisters.

Concepts: Immune system, Antibody, Immunology, Viral diseases, Herpes zoster, Chickenpox, Postherpetic neuralgia, Varicella zoster virus

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Viral diseases transmitted via Aedes mosquitoes are on the rise, such as Zika, dengue, and chikungunya. Novel tools to mitigate Aedes mosquitoes-transmitted diseases are urgently needed. We tested whether commercially insecticide-impregnated school uniforms can reduce dengue incidence in school children.

Concepts: Mosquito, Aedes aegypti, Aedes, Dengue fever, Viral diseases, Mosquito control