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1.  Simple reverse genetics systems for Asian and African Zika viruses 
Scientific Reports  2016;6:39384.
Zika virus (ZIKV), a typical example of a re‐emerging pathogen, recently caused large outbreaks in Pacific islands and the Americas, associated with congenital diseases and neurological complications. Deciphering the natural history, ecology and pathophysiology of this mosquito-borne pathogen requires effective reverse genetics tools. In the current study, using the bacterium-free ‘Infectious Subgenomic Amplicons’ (ISA) method, we generated and made available to the scientific community via the non-profit European Virus Archive collection, two simple and performing reverse genetics systems for ZIKV. One is based on an Asian ZIKV strain belonging to the outbreak lineage (French Polynesia 2013). The second was designed from the sequence of a low-passaged ZIKV African strain (Dakar 1984). Using the ISA procedure, we derived wild-type and a variety of specifically engineered ZIKVs in days (intra- and inter-lineage chimeras). Since they are based on low-passaged ZIKV strains, these engineered viruses provide ideal tools to study the effect of genetic changes observed in different evolutionary time-scales of ZIKV as well as pathophysiology of ZIKV infections.
doi:10.1038/srep39384
PMCID: PMC5171905  PMID: 27991555
2.  Complete Coding Sequence of Zika Virus from a French Polynesia Outbreak in 2013 
Genome Announcements  2014;2(3):e00500-14.
Zika virus is an arthropod-borne Flavivirus member of the Spondweni serocomplex, transmitted by Aedes mosquitoes. We report here the complete coding sequence of a Zika virus strain belonging to the Asian lineage, isolated from an infected patient returning from French Polynesia, an epidemic area in 2013/2014.
doi:10.1128/genomeA.00500-14
PMCID: PMC4047448  PMID: 24903869
3.  Viral aetiology influenza like illnesses in Santa Cruz, Bolivia (2010–2012) 
Virology Journal  2014;11:35.
Background
Acute respiratory infections represent a serious public health issue worldwide but virological aetiologies of Influenza Like Illnesses (ILIs) remain largely unknown in developing countries. This study represents the first attempt to characterise viral aetiologies of ILIs in Bolivia.
Methods
It was performed in Santa Cruz city from January 2010 to September 2012, based on 564 naso-pharyngeal swabs collected in a National Reference Laboratory and real-time PCR techniques, viral cultures and phylogenetic analyses.
Results
50.2% of samples were positive for at least one virus with influenza viruses (Flu A: ~15%; Flu B: ~9%), rhinoviruses (~8%), coronaviruses (~5%) and hRSV (~4%) being the most frequently identified. The pattern of viral infections varied according to age groups. The elucidation rate was the highest (>60%) amongst patients under 10 yo and the lowest (<40%) amongst patients ≥60 yo. Nearly 3% of samples showed dual viral infections. Epidemiological peaks were associated with a predominant virus but generally included 30-50% of infections by different viruses. Unexpectedly, the frequency of influenza in the 0–4 yo population was very low and a complete hRSV eclipse occurred in 2011. Genetic analyses indicated that distinct evolutionary lineages of Flu A(H1N1)pdm2009, Flu A/H3N2 and Flu B have co-circulated in Bolivia in the study period, originating from Central and North America, Europe, Asia and Australia.
Conclusion
Our results emphasise the requirement for a reinforced epidemiological and genetic follow-up of influenza and other ILIs in Bolivia to further inform the preparation of vaccines used in the region, guide vaccination campaigns and improve the medical management of patients.
doi:10.1186/1743-422X-11-35
PMCID: PMC4015617  PMID: 24564892
Epidemiology; Influenza like illness; Bolivia; South America; Influenza A(H1N1)pdm2009; Influenza phylogeny; Respiratory infections
4.  Molecular Epidemiology of Yellow Fever in Bolivia from 1999 to 2008 
Yellow fever (YF) is a serious public health problem in Bolivia since at least the 19th century. Surprisingly, very limited information has been made available to date regarding the genetic characterisation and epidemiology of Bolivian YF virus (YFV) strains. Here, we conducted the genetic characterization of 12 human isolates of YFV collected in Bolivia between 1999 and 2008, by sequencing and analysis of two regions of the viral genome: a fragment encoding structural proteins “PrM” (premembrane and envelope) and a distal region “EMF,” spanning the end of the virus genome. Our study reveals a high genetic diversity of YFV strains circulating in Bolivia during the last decade: we identified not only “Peruvian-like” genotype II viruses (related to previously characterized Bolivian strains), but also, for the fist time, “Brazilian-like” genotype I viruses. During the complete period of the study, only cases of “jungle” YF were detected (i.e., circulation of YFV via a sylvatic cycle) with no cluster of urban cases. However, the very significant spread of the Aedes aegypti mosquito across Bolivian cities threatens the country with the reappearance of an urban YFV transmission cycle and thus is required a sustained epidemiological surveillance.
doi:10.1089/vbz.2010.0017
PMCID: PMC3496372  PMID: 20925524
Aedes; Epidemiology; Yellow fever
5.  Molecular Epidemiological Analysis of Dengue Fever in Bolivia from 1998 to 2008 
Dengue fever was first recognized in Bolivia in 1931. However, very limited information was available to date regarding the genetic characterization and epidemiology of Bolivian dengue virus strains. Here, we performed genetic characterization of the full-length envelope gene of 64 Bolivian isolates from 1998 to 2008 and investigated their origin and evolution to determine whether strains circulated simultaneously or alternatively, and whether or not multiple introductions of distinct viral variants had occurred during the period studied. We determined that, during the last decade, closely related viruses circulated during several consecutive years (5, 6, and 6 years for DENV-1, DENV-2, and DENV-3, respectively) and the co-circulation of two or even three serotypes was observed. Emergence of new variants (distinct from those identified during the previous episodes) was identified in the case of DENV-1 (2007 outbreak) and DENV-2 (2001 outbreak). In all cases, it is likely that the viruses originated from neighboring countries.
doi:10.1089/vbz.2008.0187
PMCID: PMC3496373  PMID: 19505253
Dengue; Epidemiology; Genetics
6.  Molecular Epidemiology of Yellow Fever in Bolivia from 1999 to 2008 
Abstract
Yellow fever (YF) is a serious public health problem in Bolivia since at least the 19th century. Surprisingly, very limited information has been made available to date regarding the genetic characterisation and epidemiology of Bolivian YF virus (YFV) strains. Here, we conducted the genetic characterization of 12 human isolates of YFV collected in Bolivia between 1999 and 2008, by sequencing and analysis of two regions of the viral genome: a fragment encoding structural proteins “PrM” (premembrane and envelope) and a distal region “EMF,” spanning the end of the virus genome. Our study reveals a high genetic diversity of YFV strains circulating in Bolivia during the last decade: we identified not only “Peruvian-like” genotype II viruses (related to previously characterized Bolivian strains), but also, for the fist time, “Brazilian-like” genotype I viruses. During the complete period of the study, only cases of “jungle” YF were detected (i.e., circulation of YFV via a sylvatic cycle) with no cluster of urban cases. However, the very significant spread of the Aedes aegypti mosquito across Bolivian cities threatens the country with the reappearance of an urban YFV transmission cycle and thus is required a sustained epidemiological surveillance.
doi:10.1089/vbz.2010.0017
PMCID: PMC3496372  PMID: 20925524
Aedes; Epidemiology; Yellow fever
7.  Comparative Production Analysis of Three Phlebovirus Nucleoproteins under Denaturing or Non-Denaturing Conditions for Crystallographic Studies 
Nucleoproteins (NPs) encapsidate the Phlebovirus genomic (-)RNA. Upon recombinant expression, NPs tend to form heterogeneous oligomers impeding characterization of the encapsidation process through crystallographic studies. To overcome this problem, we set up a standard protocol in which production under both non-denaturing and denaturing/refolding conditions can be investigated and compared. The protocol was applied for three phlebovirus NPs, allowing an optimized production strategy for each of them. Remarkably, the Rift Valley fever virus NP was purified as a trimer under native conditions and yielded protein crystals whereas the refolded version could be purified as a dimer. Yields of trimeric Toscana virus NP were higher from denaturing than from native condition and lead to crystals. The production of Sandfly Fever Sicilian virus NP failed in both protocols. The comparative protocols described here should help in rationally choosing between denaturing or non-denaturing conditions, which would finally result in the most appropriate and relevant oligomerized protein species. The structure of the Rift Valley fever virus NP has been recently published using a refolded monomeric protein and we believe that the process we devised will contribute to shed light in the genome encapsidation process, a key stage in the viral life cycle.
Author Summary
Phleboviruses have a worldwide distribution and are usually represented by their prototype Rift Valley fever virus that can have a great impact on health and economy in Africa. The genome of phleboviruses is a segmented negative strand RNA that is encapsidated by the nucleoprotein. The structure of the monomeric nucleoprotein has been recently published but it's not sufficient to decipher a convincing mechanism for the nucleoprotein oligomerization. In order to understand this key step in the virus life cycle, the purification of oligomers homogeneous in size would be a key step to launch structural studies. To that aim, a procedure relying on recombinant protein production in both denaturing and non-denaturing conditions was applied to three phlebovirus nucleoproteins. Although the best production pipeline differs for each protein, pure and homogeneous solutions of Rift Valley fever virus and Toscana virus nucleoproteins were successfully obtained. Both proteins, behaving as apparent trimers in solution, lead to protein crystallization, a starting point to understand the genome encapsidation through structural studies.
doi:10.1371/journal.pntd.0000936
PMCID: PMC3014985  PMID: 21245924
8.  The N-Terminal Domain of the Arenavirus L Protein Is an RNA Endonuclease Essential in mRNA Transcription 
PLoS Pathogens  2010;6(9):e1001038.
Arenaviridae synthesize viral mRNAs using short capped primers presumably acquired from cellular transcripts by a ‘cap-snatching’ mechanism. Here, we report the crystal structure and functional characterization of the N-terminal 196 residues (NL1) of the L protein from the prototypic arenavirus: lymphocytic choriomeningitis virus. The NL1 domain is able to bind and cleave RNA. The 2.13 Å resolution crystal structure of NL1 reveals a type II endonuclease α/β architecture similar to the N-terminal end of the influenza virus PA protein. Superimposition of both structures, mutagenesis and reverse genetics studies reveal a unique spatial arrangement of key active site residues related to the PD…(D/E)XK type II endonuclease signature sequence. We show that this endonuclease domain is conserved and active across the virus families Arenaviridae, Bunyaviridae and Orthomyxoviridae and propose that the arenavirus NL1 domain is the Arenaviridae cap-snatching endonuclease.
Author Summary
The Arenaviridae virus family includes several life-threatening human pathogens that cause meningitis or hemorrhagic fever. These RNA viruses replicate and transcribe their genome using an RNA synthesis machinery for which no structural data currently exist. They synthesize viral mRNAs using short capped primers presumably acquired from cellular transcripts by a ‘cap-snatching’ mechanism thought to involve the large L protein, which carries RNA-dependent RNA polymerase signature sequences. Here, we report the crystal structure and functional characterization of an isolated N-terminal domain of the L protein (NL1) from the prototypic arenavirus: lymphocytic choriomeningitis virus. The NL1 domain is able to bind and cleave RNA. The 2.13 Å resolution crystal structure of NL1 reveals a type II endonuclease α/β architecture similar to the N-terminal end of the influenza virus PA protein. Superimposition of both structures and mutagenesis studies reveal a unique spatial arrangement of key active site residues related to the PD…(D/E)XK type II endonuclease signature sequence. Reverse genetic studies show that mutation of active site residues selectively abolish transcription, not replication. We show that this endonuclease domain is conserved and active across the virus families: Arenaviridae, Bunyaviridae and Orthomyxoviridae and propose that the arenavirus NL1 domain is the Arenaviridae cap-snatching endonuclease.
doi:10.1371/journal.ppat.1001038
PMCID: PMC2940758  PMID: 20862324
9.  Structure and functionality in flavivirus NS-proteins: Perspectives for drug design 
Antiviral Research  2010;87(2):125-148.
Flaviviridae are small enveloped viruses hosting a positive-sense single-stranded RNA genome. Besides yellow fever virus, a landmark case in the history of virology, members of the Flavivirus genus, such as West Nile virus and dengue virus, are increasingly gaining attention due to their re-emergence and incidence in different areas of the world. Additional environmental and demographic considerations suggest that novel or known flaviviruses will continue to emerge in the future. Nevertheless, up to few years ago flaviviruses were considered low interest candidates for drug design. At the start of the European Union VIZIER Project, in 2004, just two crystal structures of protein domains from the flaviviral replication machinery were known. Such pioneering studies, however, indicated the flaviviral replication complex as a promising target for the development of antiviral compounds. Here we review structural and functional aspects emerging from the characterization of two main components (NS3 and NS5 proteins) of the flavivirus replication complex. Most of the reviewed results were achieved within the European Union VIZIER Project, and cover topics that span from viral genomics to structural biology and inhibition mechanisms. The ultimate aim of the reported approaches is to shed light on the design and development of antiviral drug leads.
doi:10.1016/j.antiviral.2009.11.009
PMCID: PMC3918146  PMID: 19945487
BVDV, bovine viral diarrhea virus; C, capsid protein; CSFV, classical swine fever virus; CCHFV, Crimean-Congo hemorrhagic fever virus; CPE, cyto-pathogenic effect; dsRNA, double-stranded RNA; ER, endoplasmic reticulum; E, envelope protein; GMP, guanosine monophosphate; GTP, guanosine triphosphate; GTase, guanylyltransferase; NS3Hel, helicase; HIV, Human Immunodeficiency Virus I; HCV, hepatitis C virus; HBS, high affinity binding site; IMP, Inosine 5′-monophosphate; LBS, low-affinity binding site; M, membrane protein; NS5MTase, methyltransferase; N7MTase, (guanine-N7)-methyltransferase; 2′OMTase, (nucleoside-2′-O-)-methyltransferase; NS, non-structural; NLS, nuclear localization sequences; NS3Pro, protease; RC, replication-competent complex; RSV, respiratory syncytial virus; NS5RdRp, RNA-dependent RNA polymerase; NS3RTPase, RNA triphosphatase; AdoMet, S-adenosyl-L-methionine; ssRNA, single-stranded RNA; T-705 RMP, T-705-ribofuranosyl-5′-monophosphate; VIZIER, Viral Enzymes Involved in Replication; Flavivirus; Flaviviral NS3 protein; Flaviviral NS5 protein; Protease; Helicase; Polymerase; Methyltransferase; Flavivirus protein structure; Antivirals; VIZIER Consortium
10.  Dengue Virus Type 3 Infection in Traveler Returning from West Africa 
Emerging Infectious Diseases  2009;14(11):1081-8.
doi:10.3201/eid1511.081736
PMCID: PMC2857216  PMID: 19891895
Dengue; West Africa; Côte d’Ivoire; surveillance; traveler; viruses; letter

Results 1-10 (10)