Flavonoids as molecules with Anti-Zika virus activity

Zika virus (ZIKV) is an arthropod-born virus that is mainly transmitted to humans by mosquitoes of the genus Aedes spp. Since its first isolation in 1947, only a few human cases had been described until large outbreaks occurred on Yap Island (2007), French Polynesia (2013), and Brazil (2015). Most ZIKV-infected individuals are asymptomatic or present with a self-limiting disease and nonspecific symptoms such as fever, myalgia, and headache. However, in French Polynesia and Brazil, ZIKV outbreaks led to the diagnosis of congenital malformations and microcephaly in newborns and Guillain-Barré syndrome (GBS) in adults. These new clinical presentations raised concern from public health authorities and highlighted the need for anti-Zika treatments and vaccines to control the neurological damage caused by the virus. Despite many efforts in the search for an effective treatment, neither vaccines nor antiviral drugs have become available to control ZIKV infection and/or replication. Flavonoids, a class of natural compounds that are well-known for possessing several biological properties, have shown activity against different viruses. Additionally, the use of flavonoids in some countries as food supplements indicates that these molecules are nontoxic to humans. Thus, here, we summarize knowledge on the use of flavonoids as a source of anti-ZIKV molecules and discuss the gaps and challenges in this area before these compounds can be considered for further preclinical and clinical trials

PEÇONHA DE Tityus bahiensis REDUZ PROLIFERAÇÃO DE Toxoplasma gondii (CEPA RH) E PRODUÇÃO DE IL-8 NAS CÉLULAS HeLa

Toxoplasma gondii é o protozoário causador da toxoplasmose, infecção que apresenta caráter grave em imunocomprometidos. Os fármacos convencionais para o tratamento desta infecção apresentam alta toxicidade. Peçonhas de escorpião são investigadas uma vez que apresentam efeito direto sobre microrganismos. Objetivo deste trabalho foi avaliar o potencial toxoplasmicida e imunomodulador da peçonha do escorpião Tityus bahiensis (pTb) sobre taquizoítas da cepa RH de T. gondii em células HeLa. Para averiguar índices de infecção e proliferação celular de formas taquizoítas de T. gondii (5x105) em células HeLa (1x105). Foi avaliada, também, a produção de citocinas nas células HeLa infectadas e tratados com pTb (15 µg/mL). Os resultados demonstram que, após 24 horas de tratamento, nenhuma das concentrações apresentou foi citoxicidade. A pTb não alterou os níveis de infecção das células. Na proliferação intracelular a pTb induziu redução de 17,92% na concentração 4 g/mL, 10,18%, utilizando 7,5 g/mL e 16,82% com 15 g/mL. A pTb modulou apenas a produção de IL-8, reduzindo sua produção em 87,32%. Concluímos que a pTb exerce ação imunomoduladora e anti-proliferativa sobre células HeLa infectadas com Toxoplasma gondii (cepa RH)

Amblyomma sculptum Salivary PGE2 Modulates the Dendritic Cell-Rickettsia rickettsii Interactions in vitro and in vivo

Amblyomma sculptum is an important vector of Rickettsia rickettsii, causative agent of Rocky Mountain spotted fever and the most lethal tick-borne pathogen affecting humans. To feed on the vertebrate host's blood, A. sculptum secretes a salivary mixture, which may interact with skin resident dendritic cells (DCs) and modulate their function. The present work was aimed at depicting the A. sculptum saliva-host DC network and the biochemical nature of the immunomodulatory component(s) involved in this interface. A. sculptum saliva inhibits the production of inflammatory cytokines by murine DCs stimulated with LPS. The fractionation of the low molecular weight salivary content by reversed-phase chromatography revealed active fractions eluting from 49 to 55% of the acetonitrile gradient. Previous studies suggested that this pattern of elution matches with that observed for prostaglandin E2 (PGE2) and the molecular identity of this lipid mediator was unambiguously confirmed by a new high-resolution mass spectrometry methodology. A productive infection of murine DCs by R. rickettsii was demonstrated for the first time leading to proinflammatory cytokine production that was inhibited by both A. sculptum saliva and PGE2, a result also achieved with human DCs. The adoptive transfer of murine DCs incubated with R. rickettsii followed by treatment with A. sculptum saliva or PGE2 did not change the cytokine profile associated to cellular recall responses while IgG2a-specific antibodies were decreased in the serum of these mice. Together, these findings emphasize the role of PGE2 as a universal immunomodulator of tick saliva. In addition, it contributes to new approaches to explore R. rickettsii-DC interactions both in vitro and in vivo

Sodium nitroprusside has leishmanicidal activity independent of iNOS

Abstract: INTRODUCTION: Leishmaniasis is a zoonotic disease caused by protozoa of the genus Leishmania . Cutaneous leishmaniasis is the most common form, with millions of new cases worldwide each year. Treatments are ineffective due to the toxicity of existing drugs and the resistance acquired by certain strains of the parasite. METHODS: We evaluated the activity of sodium nitroprusside in macrophages infected with Leishmania (Leishmania) amazonensis . Phagocytic and microbicidal activity were evaluated by phagocytosis assay and promastigote recovery, respectively, while cytokine production and nitrite levels were determined by ELISA and by the Griess method. Levels of iNOS and 3-nitrotyrosine were measured by immunocytochemistry. RESULTS: Sodium nitroprusside exhibited in vitro antileishmanial activity at both concentrations tested, reducing the number of amastigotes and recovered promastigotes in macrophages infected with L. amazonensis . At 1.5µg/mL, sodium nitroprusside stimulated levels of TNF-α and nitric oxide, but not IFN-γ. The compound also increased levels of 3-nitrotyrosine, but not expression of iNOS, suggesting that the drug acts as an exogenous source of nitric oxide. CONCLUSIONS: Sodium nitroprusside enhances microbicidal activity in Leishmania -infected macrophages by boosting nitric oxide and 3-nitrotyrosine

Detection and clearance of a mosquito densovirus contaminant from laboratory stocks of Zika virus

BACKGROUND The Zika virus (ZIKV) epidemics that affected South America in 2016 raised several research questions and prompted an increase in studies in the field. The transient and low viraemia observed in the course of ZIKV infection is a challenge for viral isolation from patient serum, which leads to many laboratories around the world sharing viral strains for their studies. C6/36 cells derived from Aedes albopictus larvae are commonly used for arbovirus isolation from clinical samples and for the preparation of viral stocks. OBJECTIVES Here, we report the contamination of two widely used ZIKV strains by Brevidensovirus, here designated as mosquito densovirus (MDV). METHODS Molecular and immunological techniques were used to analyse the MDV contamination of ZIKV stocks. Also, virus passages in mammalian cell line and infecting susceptible mice were used to MDV clearance from ZIKV stocks. FINDINGS MDV contamination was confirmed by molecular and immunological techniques and likely originated from C6/36 cultures commonly used to grow viral stocks. We applied two protocols that successfully eliminated MDV contamination from ZIKV stocks, and these protocols can be widely applied in the field. As MDV does not infect vertebrate cells, we performed serial passages of contaminated stocks using a mammalian cell line and infecting susceptible mice prior to re-isolating ZIKV from the animals’ blood serum. MDV elimination was confirmed with immunostaining, polymerase chain reaction (PCR), and analysis of the mosquitoes that were allowed to feed on the infected mice. MAIN CONCLUSIONS Since the putative impact of viral contaminants in ZIKV strains generally used for research purposes is unknown, researchers working in the field must be aware of potential contaminants and test viral stocks to certify sample purity

Genetic and biological characterisation of Zika virus isolates from different brazilian regions

Submitted by Manoel Barata ([email protected]) on 2019-09-02T17:51:08Z No. of bitstreams: 1 1678-8060-mioc-114.pdf: 3706408 bytes, checksum: 5e14ddf11ac66c68ccd9bf9acf46ec13 (MD5)Approved for entry into archive by Manoel Barata ([email protected]) on 2019-09-13T19:13:42Z (GMT) No. of bitstreams: 1 1678-8060-mioc-114.pdf: 3706408 bytes, checksum: 5e14ddf11ac66c68ccd9bf9acf46ec13 (MD5)Made available in DSpace on 2019-09-13T19:13:42Z (GMT). No. of bitstreams: 1 1678-8060-mioc-114.pdf: 3706408 bytes, checksum: 5e14ddf11ac66c68ccd9bf9acf46ec13 (MD5) Previous issue date: 2019Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Regulação da Expressão Gênica. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Fundação Oswaldo Cruz. Instituto Carlos Chagas. Laboratório de Virologia Molecular. Curitiba, PR, Brasil.Zika virus (ZIKV) infections reported in recent epidemics have been linked to clinical complications that had never been associated with ZIKV before. Adaptive mutations could have contributed to the successful emergence of ZIKV as a global health threat to a nonimmune population. However, the causal relationships between the ZIKV genetic determinants, the pathogenesis and the rapid spread in Latin America and in the Caribbean remain widely unknown. The aim of this study was to characterise three ZIKV isolates obtained from patient samples during the 2015/2016 brazilian epidemics. As methods for this study, the ZIKV genomes of these strains were completely sequenced and in vitro infection kinetics experiments were carried out in cell lines and human primary cells. As findings, are eight nonsynonymous substitutions throughout the viral genome of the three Brazilian isolates were identified. Infection kinetics experiments were carried out with mammalian cell lines A549, Huh7.5, Vero E6 and human monocyte-derived dendritic cells (mdDCs) and insect cells (Aag2, C6/36 and AP61) and suggest that some of these mutations might be associated with distinct viral fitness. The clinical isolates also presented differences in their infectivity rates when compared to the ellestablished ZIKV strains (MR766 and PE243), especially in their abilities to infect mammalian cells. As main conclusions had that Genomic analysis of three recent ZIKV isolates revealed some nonsynonymous substitutions, which could have an impact on the viral fitness in mammalian and insect cells

Brazilian Propolis Antileishmanial and Immunomodulatory Effects

The antileishmanial and immunomodulatory effects of propolis collected in Botucatu, São Paulo State, Brazil, were evaluated in Leishmania (Viannia) braziliensis experimental infection. The antileishmanial effect of propolis on promastigote forms was verified by reducing growth and by promoting morphologic alterations observed by scanning electron microscopy. In in vitro immunomodulatory assays, macrophages were pretreated with propolis and then infected with L. (V.) braziliensis. In vivo, supernatants from liver cells and peritoneal exudate of BALB/c mice pretreated with propolis and infected with Leishmania (107/mL promastigotes) were collected, and TNF-α and IL-12 were measured by ELISA. Macrophages incubated with propolis showed a significant increase in interiorization and further killing of parasites. An increased TNF-α production was seen in mice pretreated with propolis, whereas IL-12 was downregulated during the infection. In conclusion, Brazilian propolis showed a direct action on the parasite and displayed immunomodulatory effects on murine macrophages, even though the parasite has been reported to affect the activation pathways of the cell. The observed effects could be associated with the presence of phenolic compounds (flavonoids, aromatic acids, and benzopyranes), di- and triterpenes, and essential oils found in our propolis sample

Brazilian propolis antileishmanial and immunomodulatory effects

The antileishmanial and immunomodulatory effects of propolis collected in Botucatu, São Paulo State, Brazil, were evaluated in Leishmania (Viannia) braziliensis experimental infection. The antileishmanial effect of propolis on promastigote forms was verified by reducing growth and by promoting morphologic alterations observed by scanning electron microscopy. In in vitro immunomodulatory assays, macrophages were pretreated with propolis and then infected with L. (V.) braziliensis. In vivo, supernatants from liver cells and peritoneal exudate of BALB/c mice pretreated with propolis and infected with Leishmania (107/mL promastigotes) were collected, and TNF- α and IL-12 were measured by ELISA. Macrophages incubated with propolis showed a significant increase in interiorization and further killing of parasites. An increased TNF- α production was seen in mice pretreated with propolis, whereas IL-12 was downregulated during the infection. In conclusion, Brazilian propolis showed a direct action on the parasite and displayed immunomodulatory effects on murine macrophages, even though the parasite has been reported to affect the activation pathways of the cell. The observed effects could be associated with the presence of phenolic compounds (flavonoids, aromatic acids, and benzopyranes), di- and triterpenes, and essential oils found in our propolis sample. © 2013 Suelen Santos da Silva et al