title: Identification of large variation in pfcrt, pfmdr-1 and pfubp-1 markers in Plasmodium falciparum isolates from Ethiopia and Tanzania.
abstract: BACKGROUND
  Plasmodium falciparum resistance to anti-malarials is a major drawback in effective malaria control and elimination globally. Artemisinin-combination therapy (ACT) is currently the key first-line treatment for uncomplicated falciparum malaria. Plasmodium falciparum genetic signatures at pfmdr-1, pfcrt, and pfubp-1 loci are known to modulate in vivo and in vitro parasite response to ACT. The objective of this study was to assess the distribution of these resistance gene markers in isolates collected from different malaria transmission intensity in Ethiopia and Tanzania.
  
  
  METHODS
  Plasmodium falciparum clinical isolates were collected from different regions of Ethiopia and Tanzania. Genetic polymorphisms in the genes pfcrt, pfmdr-1 and pfubp-1 were analysed by PCR and sequencing. Frequencies of the different alleles in the three genes were compared within and between regions, and between the two countries.
  
  
  RESULTS
  The majority of the isolates from Ethiopia were mutant for the pfcrt 76 and wild-type for pfmdr-1 86. In contrast, the majority of the Tanzanian samples were wild-type for both pfcrt and pfmdr-1 loci. Analysis of a variable linker region in pfmdr-1 showed substantial variation in isolates from Tanzania as compared to Ethiopian isolates that had minimal variation. Direct sequencing of the pfubp-1 region showed that 92.8% (26/28) of the Ethiopian isolates had identical genome sequence with the wild type reference P. falciparum strain 3D7. Of 42 isolates from Tanzania, only 13 (30.9%) had identical genome sequences with 3D7. In the Tanzanian samples, 10 variant haplotypes were identified.
  
  
  CONCLUSIONS
  The majority of Ethiopian isolates carried the main marker for chloroquine (CQ) resistance, while the majority of the samples from Tanzania carried markers for CQ susceptibility. Polymorphic genes showed substantially more variation in Tanzanian isolates. The low variability in the polymorphic region of pfmdr-1 in Ethiopia may be a consequence of low transmission intensity as compared to high transmission intensity and large variations in Tanzania.
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia. lgolassa@gmail.com.|Armauer Hansen Research Institute, Addis Ababa, Ethiopia. lgolassa@gmail.com.
authors.forename: Lemu
authors.initials: L
authors.lastname: Golassa
authors.affiliation: Department of Biochemistry, Catholic University of Health and Allied Sciences-Bugando, Mwanza, Tanzania. erasmuskamugisha@yahoo.com.
authors.forename: Erasmus
authors.initials: E
authors.lastname: Kamugisha
authors.affiliation: National Institute for Medical Research, Tanga, Tanzania. deusishe@yahoo.com.
authors.forename: Deus S
authors.initials: DS
authors.lastname: Ishengoma
authors.affiliation: National Institute for Medical Research, Tanga, Tanzania. vitobaraka@gmail.com.|International Health Unit, Department of Epidemiology, University of Antwerp, Antwerp, Belgium. vitobaraka@gmail.com.
authors.forename: Vito
authors.initials: V
authors.lastname: Baraka
authors.affiliation: The Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania. alex.shayo@mail.com.
authors.forename: Alex
authors.initials: A
authors.lastname: Shayo
authors.affiliation: Department of Biology, LeTourneau University, Longview, TX, USA. fredbaliraine@letu.edu.
authors.forename: Frederick N
authors.initials: FN
authors.lastname: Baliraine
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden. nizar.enweji@imbim.uu.se.
authors.forename: Nizar
authors.initials: N
authors.lastname: Enweji
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia. be7roro@gmail.com.
authors.forename: Berhanu
authors.initials: B
authors.lastname: Erko
authors.affiliation: Armauer Hansen Research Institute, Addis Ababa, Ethiopia. aseffaa@gmail.com.
authors.forename: Abraham
authors.initials: A
authors.lastname: Aseffa
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden. choy.angel@gmail.com.
authors.forename: Angel
authors.initials: A
authors.lastname: Choy
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden. gote.swedberg@imbim.uu.se.
authors.forename: Göte
authors.initials: G
authors.lastname: Swedberg
mesh_terms: D000962:Antimalarials / Q000494:pharmacology / Q000627:therapeutic use; D004351:Drug Resistance; D005002:Ethiopia; D005838:Genotype; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D013636:Tanzania
chemical_list: D000962:Antimalarials; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D015800:Protozoan Proteins; C513498:Mdr1 protein, Plasmodium falciparum; C416369:PfCRT protein, Plasmodium falciparum