The cyanobacterial saxitoxin exacerbates neural cell death and brain malformations induced by zika virus

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water sup-plies of NE compared to other regions of Brazil. Experimentally, we described that STX dou-bled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.Fil: Pedrosa, Carolina da S. G.. D’Or Institute for Research and Education; BrasilFil: Souza, Leticia R. Q.. D’Or Institute for Research and Education; BrasilFil: Gomes, Tiago A.. Universidade Federal do Rio de Janeiro; Brasil. Instituto Oswaldo Cruz; BrasilFil: de Lima, Caroline V. F.. D’Or Institute for Research and Education; BrasilFil: Ledur, Pitia F.. D’Or Institute for Research and Education; BrasilFil: Karmirian, Karina. D’Or Institute for Research and Education; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Barbeito Andrés, Jimena. Universidade Federal do Rio de Janeiro; Brasil. Universidad Nacional Arturo Jauretche. Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos. Provincia de Buenos Aires. Ministerio de Salud. Hospital Alta Complejidad en Red El Cruce Dr. Néstor Carlos Kirchner Samic. Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos; ArgentinaFil: Costa, Marcelo do N.. Universidade Federal do Rio de Janeiro; BrasilFil: Higa, Luiza M.. Universidade Federal do Rio de Janeiro; BrasilFil: Rossi, Átila D.. Universidade Federal do Rio de Janeiro; BrasilFil: Bellio, Maria. Universidade Federal do Rio de Janeiro; BrasilFil: Tanuri, Amilcar. Universidade Federal do Rio de Janeiro; BrasilFil: Prata Barbosa, Arnaldo. D’Or Institute for Research and Education; BrasilFil: Tovar Moll, Fernanda. D’Or Institute for Research and Education; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Garcez, Patricia P.. Universidade Federal do Rio de Janeiro; BrasilFil: Lara, Flavio A.. Instituto Oswaldo Cruz; BrasilFil: Molica, Renato J. R.. Universidad Federal Rural Pernambuco; BrasilFil: Rehen, Stevens K.. D’Or Institute for Research and Education; Brasil. Universidade Federal do Rio de Janeiro; Brasi

Receptors and routes of dengue virus entry into the host cells

© FEMS 2014. All rights reservedDengue is the most prevalent arthropod-borne viral disease, caused by dengue virus, a member of the Flaviviridae family. Its worldwide incidence is now a major health problem, with 2.5 billion people living in risk areas. In this review, we integrate the structural rearrangements of each viral protein and their functions in all the steps of virus entry into the host cells. We describe in detail the putative receptors and attachment factors in mammalian and mosquito cells, and the recognition of viral immunocomplexes via Fcγ receptor in immune cells. We also discuss that virus internalization might occur through distinct entry pathways, including clathrin-mediated or non-classical clathrin-independent endocytosis, depending on the host cell and virus serotype or strain. The implications of viral maturation in virus entry are also explored. Finally, we discuss the mechanisms of viral genome access to the cytoplasm. This includes the role of low pH-induced conformational changes in the envelope protein that mediate membrane fusion, and original insights raised by our recent work that supports the hypothesis that capsid protein would also be an active player in this process, acting on viral genome translocation into the cytoplasm.This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil, Projects 471239/2012-7 and 306669/2013-7), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ, Brazil, Projects E-26/102.919/2011 and E-26/111.668/2013), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil, Project 171/2012), Fundação para a Ciência e Tecnologia – Ministério da Educação e Ciência (FCT-MEC, Portugal, Project PTDC/QUI-BIQ/112929/2009)

Modulation of α-enolase post-translational modifications by dengue virus: increased secretion of the basic isoforms in infected hepatic cells.

Hepatic cells are major sites of dengue virus (DENV) replication and liver injury constitutes a characteristic of severe forms of dengue. The role of hepatic cells in dengue pathogenesis is not well established, but since hepatocytes are the major source of plasma proteins, changes in protein secretion by these cells during infection might contribute to disease progression. Previously, we showed that DENV infection alters the secretion pattern of hepatic HepG2 cells, with α-enolase appearing as one of the major proteins secreted in higher levels by infected cells. ELISA analysis demonstrated that DENV infection modulates α-enolase secretion in HepG2 cells in a dose-dependent manner, but has no effect on its gene expression and on the intracellular content of the protein as assessed by PCR and western blot analyses, respectively. Two-dimensional western blots showed that both intracellular and secreted forms of α-enolase appear as five spots, revealing α-enolase isoforms with similar molecular weights but distinct isoeletric points. Remarkably, quantification of each spot content revealed that DENV infection shifts the isoform distribution pattern of secreted α-enolase towards the basic isoforms, whereas the intracellular protein remains unaltered, suggesting that post-translational modifications might be involved in α-enolase secretion by infected cells. These findings provide new insights into the mechanisms underlying α-enolase secretion by hepatic cells and its relationship with the role of liver in dengue pathogenesis. In addition, preliminary results obtained with plasma samples from DENV-infected patients suggest an association between plasma levels of α-enolase and disease severity. Since α-enolase binds plasminogen and modulates its activation, it is plausible to speculate the association of the increase in α-enolase secretion by infected hepatic cells with the haemostatic dysfunction observed in dengue patients including the promotion of fibrinolysis and vascular permeability alterations

TITLE: Zika virus impairs growth in human neurospheres and brain organoids

SUMMARY: We provide evidence that Zika virus infects human iPS-derived neural stem cells, causing cell death and reduced growth in neurospheres and cerebral organoids

StreptInCor did not induce T-cell cross reactivity against cardiac myosin.

<p>Splenocytes from Swiss mice (n = 6) immunized with 10 µg of StreptInCor adsorbed onto 60 µg of aluminum hydroxide (black symbols) or injected with aluminum hydroxide alone (controls, open symbols) were incubated with StreptInCor at 1 µg/mL (circles), 10 µg/mL (triangles) or cardiac myosin (diamonds). Stimulation indices ≥2.0 (dotted line) were considered positive. Each data point represents a sample, and the line represents the mean. <i>P</i> values: ** (≤0.01).</p

Chloroquine, an Endocytosis Blocking Agent, Inhibits Zika Virus Infection in Different Cell Models

Zika virus (ZIKV) infection in utero might lead to microcephaly and other congenital defects. Since no specific therapy is available thus far, there is an urgent need for the discovery of agents capable of inhibiting its viral replication and deleterious effects. Chloroquine is widely used as an antimalarial drug, anti-inflammatory agent, and it also shows antiviral activity against several viruses. Here we show that chloroquine exhibits antiviral activity against ZIKV in Vero cells, human brain microvascular endothelial cells, human neural stem cells, and mouse neurospheres. We demonstrate that chloroquine reduces the number of ZIKV-infected cells in vitro, and inhibits virus production and cell death promoted by ZIKV infection without cytotoxic effects. In addition, chloroquine treatment partially reveres morphological changes induced by ZIKV infection in mouse neurospheres

DENV infection does not modulate α-enolase gene expression and intracellular content in HepG2 cells.

<p>HepG2 cells were either mock-infected or infected with DENV (MOI = 1, 2 and 4) for 24 h. (A) ENO1 expression was measured by quantitative RT-PCR. Graph shows mean ± SEM from 5 independent experiments. (B) Western blot analysis of cell lysates proteins. Upper panel shows a representative blot and bottom panel shows the densitometric analysis of α-enolase bands normalized by the content of GAPDH. Graph shows mean ± SEM from 3 independent experiments. Comparison between mock and DENV-infected cells was analyzed by repeated measures ANOVA. (C) α-enolase content in cell lysates was measured by ELISA. Graph shows mean ± SEM from 3 independent experiments. Differences between samples from mock and DENV-infected cells were assessed by paired t test.</p

DENV infection induces α-enolase secretion in HepG2 cells.

<p>HepG2 cells were either mock-infected or infected with DENV (MOI = 1, 2 and 4) for 24 h. (A) DENV+ cells were measured by flow cytometry using an anti-DENV monoclonal antibody. Representative flow cytometry analysis of mock and DENV-infected HepG2 cells. Shaded histogram indicates DENV-infected HepG2 cells (MOI = 4) stained with an isotype control antibody, open histograms in red, blue, yellow and black show mock, DENV-infected cells with MOI = 1, MOI = 2 and MOI = 4, respectively. The inset graph shows the frequency of DENV+ cells and data represents mean ± SEM from 8 independent experiments. (B) α-enolase content in the conditioned medium was measured by ELISA. Graph shows mean ± SEM from 6 independent experiments. Differences between mock and DENV-infected cells were assessed using repeated measures ANOVA and Dunnet post-hoc test. Statistical significance compared with the control is indicated by asterisks (* <i>p</i><0.05, *** <i>p</i><0.001). (C) Correlation analysis between the frequency of DENV-infected cells and α-enolase content in the conditioned medium. The % infected cells was calculated by subtracting the mock-infected staining value from those obtained for infected cells. Relationship was assessed using Spearman correlation.</p