title: Mosquito Rasputin interacts with chikungunya virus nsP3 and determines the infection rate in Aedes albopictus.
abstract: BACKGROUND
  Chikungunya virus (CHIKV) is an arthritogenic alphavirus (family Togaviridae), transmitted by Aedes species mosquitoes. CHIKV re-emerged in 2004 with multiple outbreaks worldwide and recently reached the Americas where it has infected over a million individuals in a rapidly expanding epidemic. While alphavirus replication is well understood in general, the specific function (s) of non-structural protein nsP3 remain elusive. CHIKV nsP3 modulates the mammalian stress response by preventing stress granule formation through sequestration of G3BP. In mosquitoes, nsP3 is a determinant of vector specificity, but its functional interaction with mosquito proteins is unclear.
  
  
  METHODS
  In this research we studied the domains required for localization of CHIKV nsP3 in insect cells and demonstrated its molecular interaction with Rasputin (Rin), the mosquito homologue of G3BP. The biological involvement of Rin in CHIKV infection was investigated in live Ae. albopictus mosquitoes.
  
  
  RESULTS
  In insect cells, nsP3 localized as cytoplasmic granules, which was dependent on the central domain and the C-terminal variable region but independent of the N-terminal macrodomain. Ae. albopictus Rin displayed a diffuse, cytoplasmic localization, but was effectively sequestered into nsP3-granules upon nsP3 co-expression. Site-directed mutagenesis showed that the Rin-nsP3 interaction involved the NTF2-like domain of Rin and two conserved TFGD repeats in the C-terminal variable domain of nsP3. Although in vitro silencing of Rin did not impact nsP3 localization or CHIKV replication in cell culture, Rin depletion in vivo significantly decreased the CHIKV infection rate and transmissibility in Ae.albopictus.
  
  
  CONCLUSIONS
  We identified the nsP3 hypervariable C-terminal domain as a critical factor for granular localization and sequestration of mosquito Rin. Our study offers novel insight into a conserved virus-mosquito interaction at the molecular level, and reveals a strong proviral role for G3BP homologue Rin in live mosquitoes, making the nsP3-Rin interaction a putative target to interfere with the CHIKV transmission cycle.
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. jelke.fros@gmail.com.
authors.forename: Jelke J
authors.initials: JJ
authors.lastname: Fros
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. corinne.geertsema@wur.nl.
authors.forename: Corinne
authors.initials: C
authors.lastname: Geertsema
authors.affiliation: Institut Pasteur, Department of Virology, Arboviruses and Insect Vectors, 25-28 rue du Docteur Roux, 75724, Paris, cedex 15, France. zouache05@yahoo.fr.
authors.forename: Karima
authors.initials: K
authors.lastname: Zouache
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. jbaggen@hotmail.com.
authors.forename: Jim
authors.initials: J
authors.lastname: Baggen
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. natalia.domeradzka@wur.nl.
authors.forename: Natalia
authors.initials: N
authors.lastname: Domeradzka
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. daniel.vanleeuwen@wur.nl.
authors.forename: Daniël M
authors.initials: DM
authors.lastname: van Leeuwen
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. jflipse86@hotmail.com.
authors.forename: Jacky
authors.initials: J
authors.lastname: Flipse
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. just.vlak@wur.nl.
authors.forename: Just M
authors.initials: JM
authors.lastname: Vlak
authors.affiliation: Institut Pasteur, Department of Virology, Arboviruses and Insect Vectors, 25-28 rue du Docteur Roux, 75724, Paris, cedex 15, France. anna-bella.failloux@pasteur.fr.
authors.forename: Anna-Bella
authors.initials: AB
authors.lastname: Failloux
authors.affiliation: Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands. gorben.pijlman@wur.nl.
authors.forename: Gorben P
authors.initials: GP
authors.lastname: Pijlman
mesh_terms: D000330:Aedes / Q000821:virology*; D000569:Americas; D000818:Animals; D002646:Chikungunya virus / Q000502:physiology*; D054884:Host-Pathogen Interactions; D019476:Insect Proteins / Q000378:metabolism*; D007303:Insect Vectors / Q000821:virology*; D008969:Molecular Sequence Data; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017422:Sequence Analysis, DNA; D017361:Viral Nonstructural Proteins / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D017361:Viral Nonstructural Proteins