#Risk of #dengue in Central #Africa: #Vector competence studies with #Aedes aegypti and Aedes albopictus (Diptera: Culicidae) populations and dengue 2 virus (PLOS Negl Trop Dis., abstract)

[Source: PLOS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Risk of dengue in Central Africa: Vector competence studies with Aedes aegypti and Aedes albopictus (Diptera: Culicidae) populations and dengue 2 virus

Basile Kamgang , Marie Vazeille, Armel N. Tedjou, Theodel A. Wilson-Bahun, Aurélie P. Yougang, Laurence Mousson, Charles S. Wondji , Anna-Bella Failloux

___

Published: December 30, 2019 / DOI: https://doi.org/10.1371/journal.pntd.0007985 / This is an uncorrected proof.

 

Abstract

Introduction

Dengue is the most important mosquito-borne diseases worldwide but was considered scarce in West-Central Africa. During the last decade, dengue outbreaks have increasingly been reported in urban foci in this region suggesting major epidemiological changes. However, in Central Africa where both vectors, Aedes aegypti and Aedes albopictus are well established, the role of each species in dengue transmission remains poorly investigated.

Methodology/Principal findings

Field-collected strains of Ae. aegypti and Ae. albopictus from different ecological settings in Central Africa were experimentally challenged with dengue 2 virus (DENV-2). Mosquitoes were analysed at 14- and 21-days post-infection. Analysis provide evidence that both Ae. aegypti and Ae. albopictus in Central Africa were able to transmit dengue virus with Ae. aegypti exhibiting a higher transmission rate. Unexpectedly, two Ae. aegypti populations from Bénoué and Maroua, in northern Cameroon, were not able to transmit DENV-2.

Conclusions/Significance

We conclude that both Ae. aegypti and Ae. albopictus are susceptible to DENV-2 and may intervene as active dengue vectors. These findings highlight the urgent need to plan a vector surveillance program and control methods against dengue vectors in Central Africa in order to prevent future outbreaks.

 

Author summary

Dengue virus (DENV) is a flavivirus mainly transmitted to humans through the bite of infected mosquitoes notably Aedes aegypti and Aedes albopictus. In Central Africa where both vectors, Ae. aegypti and Ae. albopictus are well established, the role of each species in dengue transmission remains poorly investigated. Here, we assessed the vector competence of Ae. aegypti and Ae. albopictus collected in different ecological settings in Central Africa to transmit dengue 2 virus (DENV-2). We provide evidence that both Ae. aegypti and Ae. albopictus in Central Africa were able to transmit dengue virus with Ae. aegypti exhibiting a higher transmission rate. These findings could increase the risk of dengue outbreak in the region and emphasize the need for a comprehensive vector surveillance program to prevent and preparedness for an intervention in case of outbreaks.

___

Citation: Kamgang B, Vazeille M, Tedjou AN, Wilson-Bahun TA, Yougang AP, Mousson L, et al. (2019) Risk of dengue in Central Africa: Vector competence studies with Aedes aegypti and Aedes albopictus (Diptera: Culicidae) populations and dengue 2 virus. PLoS Negl Trop Dis 13(12): e0007985. https://doi.org/10.1371/journal.pntd.0007985

Editor: Duane J. Gubler, Duke-NUS GMS, SINGAPORE

Received: September 9, 2019; Accepted: December 10, 2019; Published: December 30, 2019

Copyright: © 2019 Kamgang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript.

Funding: BK was funded by the Wellcome Trust, 204862/Z/16/Z (https://wellcome.ac.uk). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Flavivirus; Dengue fever; Africa region; Mosquitoes; Aedes aegypti; Aedes albopictus.

——

Characterization of #Usutu virus NS5 protein. #Polymerase activity, protein-protein interaction and cellular localization (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Characterization of Usutu virus NS5 protein. Polymerase activity, protein-protein interaction and cellular localization.

L. Albentosa-González, P. Clemente-Casares, R. Sabariegos, A. Mas

DOI: 10.1128/AAC.01573-19

 

ABSTRACT

Usutu virus (USUV) has become increasingly relevant in recent years with large outbreaks that sporadically have affected humans, being reported in wildlife. Similarly to the rest of flaviviruses, USUV contains a positive single-stranded RNA genome which is replicated by the activity of the non-structural protein 5 (NS5). USUV NS5 shows high sequence identity with the remaining viruses in this genus. This permitted us to identify the predicted methyl-transferase domain and the RNA-dependent RNA polymerase domain (RdRpD). Owing to their high degree of conservation, viral polymerases are considered priority targets for the development of antiviral compounds. In the present study, we have cloned and expressed the entire NS5 and the RdRpD in a heterologous system and have used purified preparations for protein characterizations. We have determined the optimal reaction conditions by investigating how variations in different physicochemical parameters, such as buffer concentration, temperature, and pH, affect RNA polymerization activity. We also found that USUV polymerase, but not the full-length NS5, exhibits cooperative activity in the synthesis of RNA, and that the RdRp activity is not inhibited by Sofosbuvir. To further examine the characteristics of USUV polymerase in a more biological context, we have expressed NS5 and the RdRpD in eukaryotic cells and analyzed its subcellular location. NS5 is predominantly found in the cytoplasm, a significant proportion is directed to the nucleus and this translocation involves nuclear location signals (NLS) located, at least, between the MTase and RdRpD domains.

Copyright © 2019 Albentosa-González et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.

Keywords: Arbovirus; Flavivirus; Usutu virus; Viral pathogenesis.

—–

#Clinical and #virological #findings in patients with #Usutu virus #infection, northern #Italy, 2018 (Euro Surveill., abstract)

[Source: Eurosurveillance, full page: (LINK). Abstract, edited.]

Clinical and virological findings in patients with Usutu virus infection, northern Italy, 2018

Monia Pacenti 1,2, Alessandro Sinigaglia 2,3, Thomas Martello 2, Elena De Rui 3, Elisa Franchin 2,3, Silvana Pagni 2,3, Elektra Peta 3, Silvia Riccetti 3, Adelaide Milani 4, Fabrizio Montarsi 4, Gioia Capelli 4, Carlo Giovanni Doroldi 5, Francesco Bigolin 5, Luca Santelli 6, Lucia Nardetto 6, Marco Zoccarato 6, Luisa Barzon 2,3

Affiliations: 1 Microbiology and Virology Unit, Padua University Hospital, Padova, Italy; 2 These authors contributed equally as first authors; 3 Department of Molecular Medicine, University of Padova, Padova, Italy; 4 Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro PD, Italy; 5 Medicine Unit, Camposampiero Hospital, Azienda ULSS 6 Euganea, Padova, Italy; 6 Neurology Department, Ospedale S. Antonio, Azienda ULSS 6 Euganea, Padova, Italy

Correspondence:  Luisa Barzon

Citation style for this article: Pacenti Monia, Sinigaglia Alessandro, Martello Thomas, De Rui Elena, Franchin Elisa, Pagni Silvana, Peta Elektra, Riccetti Silvia, Milani Adelaide, Montarsi Fabrizio, Capelli Gioia, Doroldi Carlo Giovanni, Bigolin Francesco, Santelli Luca, Nardetto Lucia, Zoccarato Marco, Barzon Luisa. Clinical and virological findings in patients with Usutu virus infection, northern Italy, 2018. Euro Surveill. 2019;24(47):pii=1900180. https://doi.org/10.2807/1560-7917.ES.2019.24.47.1900180

Received: 12 Mar 2019;   Accepted: 20 May 2019

 

Abstract

Background

Usutu virus (USUV) is a mosquito-borne flavivirus, which shares its transmission cycle with the phylogenetically related West Nile virus (WNV). USUV circulates in several European countries and its activity has increased over the last 5 years.

Aim

To describe human cases of USUV infection identified by surveillance for WNV and USUV infection in the Veneto Region of northern Italy in 2018.

Methods

From 1 June to 30 November 2018, all cases of suspected autochthonous arbovirus infection and blood donors who had a reactive WNV nucleic acid test were investigated for both WNV and USUV infection by in-house molecular methods. Anti-WNV and anti-USUV IgM and IgG antibodies were detected by ELISA and in-house immunofluorescence assay, respectively; positive serum samples were further tested by WNV and USUV neutralisation assays run in parallel.

Results

Eight cases of USUV infection (one with neuroinvasive disease, six with fever and one viraemic blood donor who developed arthralgia and myalgia) and 427 cases of WNV infection were identified. A remarkable finding of this study was the persistence of USUV RNA in the blood and urine of three patients during follow-up. USUV genome sequences from two patients shared over 99% nt identity with USUV sequences detected in mosquito pools from the same area and clustered within lineage Europe 2.

Conclusions

Clinical presentation and laboratory findings in patients with USUV infection were similar to those found in patients with WNV infection. Cross-reactivity of serology and molecular tests challenged the differential diagnosis.

©  This work is licensed under a Creative Commons Attribution 4.0 International License.

Keywords: Arbovirus; Flavivirus; Usutu virus; Italy.

——

Characterization of #Usutu virus NS5 protein. #Polymerase activity, protein-protein interaction and cellular localization (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Characterization of Usutu virus NS5 protein. Polymerase activity, protein-protein interaction and cellular localization.

L. Albentosa-González, P. Clemente-Casares, R. Sabariegos, A. Mas

DOI: 10.1128/AAC.01573-19

 

ABSTRACT

Usutu virus (USUV) has become increasingly relevant in recent years with large outbreaks that sporadically have affected humans, being reported in wildlife. Similarly to the rest of flaviviruses, USUV contains a positive single-stranded RNA genome which is replicated by the activity of the non-structural protein 5 (NS5). USUV NS5 shows high sequence identity with the remaining viruses in this genus. This permitted us to identify the predicted methyl-transferase domain and the RNA-dependent RNA polymerase domain (RdRpD). Owing to their high degree of conservation, viral polymerases are considered priority targets for the development of antiviral compounds. In the present study, we have cloned and expressed the entire NS5 and the RdRpD in a heterologous system and have used purified preparations for protein characterizations. We have determined the optimal reaction conditions by investigating how variations in different physicochemical parameters, such as buffer concentration, temperature, and pH, affect RNA polymerization activity. We also found that USUV polymerase, but not the full-length NS5, exhibits cooperative activity in the synthesis of RNA, and that the RdRp activity is not inhibited by Sofosbuvir. To further examine the characteristics of USUV polymerase in a more biological context, we have expressed NS5 and the RdRpD in eukaryotic cells and analyzed its subcellular location. NS5 is predominantly found in the cytoplasm, a significant proportion is directed to the nucleus and this translocation involves nuclear location signals (NLS) located, at least, between the MTase and RdRpD domains.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Flavivirus; Usutu Virus; Sofosbuvir.

——

#Antinflammatory compound shows #therapeutic safety and efficacy against #flavivirus infection (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Anti-inflammatory compound shows therapeutic safety and efficacy against flavivirus infection

Fu-Kai Chuang, Shih-Ming Huang, Ching-Len Liao, An-Rong Lee, Shu-Pei Lien, Yu-Lung Chiu, Tsung-Hsien Chang, Pei-Ling Tsai, Ren-Jye Lin, Chih-Chin Shih, Yi-Jing Tsai, Gu-Jiun Lin, Li-Chen Yen

DOI: 10.1128/AAC.00941-19

 

ABSTRACT

Flaviviruses comprise several medically important viruses, including Japanese encephalitis virus, West Nile virus, dengue virus (DENV), yellow fever virus and Zika virus (ZIKV). A large outbreak of DENV and ZIKV occurred recently, leading to many cases of illness and death. However, despite decades of efforts, we have no clinically specific therapeutic drugs against DENV and ZIKV. Previous studies showed that inflammatory responses play a critical role in dengue and Zika pathogenesis. Thus, in this study, we examined a series of novel anti-inflammatory compounds and found that treatment with compound 2d could dose-dependently reduce viral protein expression and viral progeny production in HEK-293 and Raw264.7 cells with four serotypes of DENV and ZIKV infection. As well, considering medication safety, compound 2d could not suppress cyclooxygenase-1 (COX-1) enzymatic activities and thus could prevent bleeding side effect. Moreover, compound 2d significantly inhibited COX-2 enzymatic activities and prostaglandin E2 levels, associated with viral replication, as compared with a selective COX-2 inhibitor, celecoxib. Furthermore, administering 5 mg/kg compound 2d to DENV-2–infected AG129 mice prolonged survival and reduced viremia and serum cytokine levels. Overall, compound 2d showed therapeutic safety and efficacy in vitro and in vivo and could be further developed as a potential therapeutic agent for flavivirus infection.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Flavivirus; Antivirals.

——

#NS5 from #Dengue virus serotype 2 can adopt a conformation analogous to its #ZIKV and #JEV homologues (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

NS5 from Dengue virus serotype 2 can adopt a conformation analogous to its ZIKV and JEV homologues.

Abbas El Sahili, Tingjin Sherryl Soh, Jonas Schiltz, Aïcha Gharbi-Ayachi, Cheah Chen Seh, Pei-Yong Shi, Siew Pheng Lim, Julien Lescar

DOI: 10.1128/JVI.01294-19

 

ABSTRACT

Flavivirus non-structural protein 5 (NS5) contains a N-terminal methyltransferase domain (MTase) and a C-terminal polymerase domain (RdRp) fused through a nine-amino acid linker. While the individual NS5 domains are structurally conserved, in the full-length protein, their relative orientations fall into two classes: NS5 from JEV and ZIKV adopt one conformation, while NS5 from DENV3 another. Here, we report a crystallographic structure of NS5 from DENV2 in a conformation similar to the extended one seen in JEV and ZIKV NS5 crystal structures, albeit looser. Substituting DENV2 NS5 linker with DENV1, -3, -4, JEV and ZIKV NS5 linkers had modest or minimal effects on in vitro DENV2 MTase and RdRp activities. Heterotypic DENV NS5 linkers attenuated DENV2 replicon growth in cells, whilst JEV and ZIKV NS5 linkers abolished replication. Thus, JEV and ZIKV linkers likely hindered essential DENV2 NS5 interactions with other viral or host proteins within the virus replicative complex. Overall, this work sheds light on the dynamics of the multifunctional flavivirus NS5 protein and its interdomain linker. Targeting the NS5 linker is a possible strategy for producing attenuated flavivirus strains for vaccine design.

 

IMPORTANCE

Flaviviruses include important human pathogens such as dengue or Zika virus. NS5 is a non-structural protein essential for flavivirus RNA replication, with dual MTase and RdRp enzyme activity and thus constitutes a major drug target. Insights into NS5 structure, dynamics and evolution should inform the development of antiviral inhibitors and vaccine design. We found that NS5 from DENV2 can adopt a conformation resembling NS5 from JEV and ZIKV. Substitution of DENV2 NS5 linker with JEV and ZIKV NS5 linkers abolished DENV2 replication in cells, without significantly impacting in vitro DENV2 NS5 enzymatic activities. We propose that heterotypic Flavivirus NS5 linkers impeded DENV2 NS5 protein-protein interactions that are essential for virus replication.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Flavivirus; Dengue fever; Zika Virus; Japanese Encephalitis virus.

——

Infection of Western Gray #Kangaroos (Macropus fuliginosus) with #Australian #Arboviruses Associated with #Human #Infection (Vector Borne Zoo Dis., abstract)

[Source: Vector Borne and Zoonotic Diseases, full page: (LINK). Abstract, edited.]

Infection of Western Gray Kangaroos (Macropus fuliginosus) with Australian Arboviruses Associated with Human Infection

Narayan Gyawali, Andrew W. Taylor-Robinson, Richard S. Bradbury, Abbey Potter, and John G. Aaskov

Published Online: 26 Sep 2019

 

Abstract

More than 75 arboviruses (arthropod-borne viruses) have been identified in Australia. While Alfuy virus (ALFV), Barmah Forest virus (BFV), Edge Hill virus (EHV), Kokobera virus (KOKV), Murray Valley encephalitis virus (MVEV), Sindbis virus (SINV), Ross River virus (RRV), Stratford virus (STRV), and West Nile virus strain Kunjin (KUNV) have been associated with human infection, there remains a paucity of data regarding their respective transmission cycles and any potential nonhuman vertebrate hosts. It is likely that these viruses are maintained in zoonotic cycles involving native animals rather than solely by human-to-human transmission. A serosurvey (n = 100) was undertaken to determine the prevalence of neutralizing antibodies against a panel of Australian arboviruses in western gray kangaroos (Macropus fuliginosus) obtained from 11 locations in the midwest to southwest of Western Australia. Neutralizing antibodies against RRV were detected in 25%, against BFV in 14%, and antibodies to both viruses in 34% of serum samples. The prevalence of antibodies against these two viruses was the same in males and females, but higher in adult than in subadult kangaroos (p < 0.05). Twenty-one percent of samples had neutralizing antibodies against any one or more of the flaviviruses ALFV, EHV, KOKV, MVEV, and STRV. No neutralizing antibodies against SINV and KUNV were detected. If this sample of kangaroo sera was representative of the broader Australian population of macropods, it suggests that they are common hosts for RRV and BFV. The absence or low seroprevalence of antibodies against the remaining arboviruses suggests that they are not prevalent in the region or that kangaroos are not commonly infected with them. The detection of neutralizing antibodies to MVEV requires further investigation as this virus has not been identified previously so far south in Western Australia.

Keywords: Arbovirus; Flavivirus; Kangaroos; Wildlife; Human; Australia.

——