title: The kdr-bearing haplotype and susceptibility to Plasmodium falciparum in Anopheles gambiae: genetic correlation and functional testing.
abstract: BACKGROUND
  Members of the Anopheles gambiae species complex are primary vectors of human malaria in Africa. It is known that a large haplotype shared between An. gambiae and Anopheles coluzzii by introgression carries point mutations of the voltage-gated sodium channel gene para, including the L1014F kdr mutation associated with insensitivity to pyrethroid insecticides. Carriage of L1014F kdr is also correlated with higher susceptibility to infection with Plasmodium falciparum. However, the genetic mechanism and causative gene(s) underlying the parasite susceptibility phenotype are not known.
  
  
  METHODS
  Mosquitoes from the wild Burkina Faso population were challenged by feeding on natural P. falciparum gametocytes. Oocyst infection phenotypes were determined and were tested for association with SNP genotypes. Candidate genes in the detected locus were prioritized and RNAi-mediated gene silencing was used to functionally test for gene effects on P. falciparum susceptibility.
  
  
  RESULTS
  A genetic locus, Pfin6, was identified that influences infection levels of P. falciparum in mosquitoes. The locus segregates as a ~3 Mb haplotype carrying 65 predicted genes including the para gene. The haplotype carrying the kdr allele of para is linked to increased parasite infection prevalence, but many single nucleotide polymorphisms on the haplotype are also equally linked to the infection phenotype. Candidate genes in the haplotype were prioritized and functionally tested. Silencing of para did not influence P. falciparum infection, while silencing of a predicted immune gene, serine protease ClipC9, allowed development of significantly increased parasite numbers.
  
  
  CONCLUSIONS
  Genetic variation influencing Plasmodium infection in wild Anopheles is linked to a natural ~3 megabase haplotype on chromosome 2L that carries the kdr allele of the para gene. Evidence suggests that para gene function does not directly influence parasite susceptibility, and the association of kdr with infection may be due to tight linkage of kdr with other gene(s) on the haplotype. Further work will be required to determine if ClipC9 influences the outcome of P. falciparum infection in nature, as well as to confirm the absence of a direct influence by para.
authors.affiliation: Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, CNRS Unit of Hosts, Vectors and Pathogens (URA3012), Lab GGIV, Institut Pasteur, 28 rue du Dr Roux, 75015, Paris, France. cmitri@pasteur.fr.
authors.forename: Christian
authors.initials: C
authors.lastname: Mitri
authors.affiliation: Program in Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA. kmarkianos@enders.tch.harvard.edu.
authors.forename: Kyriacos
authors.initials: K
authors.lastname: Markianos
authors.affiliation: Centre National de Recherche et de Formation sur le Paludisme, 01 BP 2208, Ouagadougou, Burkina Faso. guelbeogo.cnrfp@fasonet.bf.
authors.forename: Wamdaogo M
authors.initials: WM
authors.lastname: Guelbeogo
authors.affiliation: Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, CNRS Unit of Hosts, Vectors and Pathogens (URA3012), Lab GGIV, Institut Pasteur, 28 rue du Dr Roux, 75015, Paris, France. bischoff@pasteur.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bischoff
authors.affiliation: Centre National de Recherche et de Formation sur le Paludisme, 01 BP 2208, Ouagadougou, Burkina Faso. gplouise@yahoo.fr.
authors.forename: Awa
authors.initials: A
authors.lastname: Gneme
authors.affiliation: Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, CNRS Unit of Hosts, Vectors and Pathogens (URA3012), Lab GGIV, Institut Pasteur, 28 rue du Dr Roux, 75015, Paris, France. kei@pasteur.fr.
authors.forename: Karin
authors.initials: K
authors.lastname: Eiglmeier
authors.affiliation: Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, CNRS Unit of Hosts, Vectors and Pathogens (URA3012), Lab GGIV, Institut Pasteur, 28 rue du Dr Roux, 75015, Paris, France. holm@pasteur.fr.
authors.forename: Inge
authors.initials: I
authors.lastname: Holm
authors.affiliation: Centre National de Recherche et de Formation sur le Paludisme, 01 BP 2208, Ouagadougou, Burkina Faso. n.fale.cnlp@fasonet.bf.
authors.forename: N'Fale
authors.initials: N
authors.lastname: Sagnon
authors.affiliation: Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, CNRS Unit of Hosts, Vectors and Pathogens (URA3012), Lab GGIV, Institut Pasteur, 28 rue du Dr Roux, 75015, Paris, France. kvernick@pasteur.fr.|Department of Microbiology, University of Minnesota, Saint Paul, MN, 55108, USA. kvernick@pasteur.fr.
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Vernick
authors.affiliation: Department of Microbiology, University of Minnesota, Saint Paul, MN, 55108, USA. mriehle@umn.edu.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Riehle
mesh_terms: D000818:Animals; D000852:Anopheles / Q000235:genetics* / Q000276:immunology / Q000469:parasitology*; D002050:Burkina Faso; D005260:Female; D008040:Genetic Linkage; D056426:Genetic Loci; D006239:Haplotypes; D007305:Insecticide Resistance; D010963:Plasmodium falciparum / Q000254:growth & development* / Q000276:immunology; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*
chemical_list: D024642:Potassium Channels, Voltage-Gated