Research

A major genetic locus controlling natural Plasmodium falciparum infection is shared by East and West African Anopheles gambiae

Michelle M Riehle¹ , Kyriacos Markianos² , Louis Lambrechts³ , Ai Xia⁴ , Igor Sharakhov⁴ , Jacob C Koella⁵ and Kenneth D Vernick¹

¹  Microbial and Plant Genomics Institute and Department of Microbiology, University of Minnesota, St. Paul, MN 55108, USA

²  Program in Genomics, Department of Medicine, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA

³  Department of Entomology, University of California, Davis, CA 95616, USA

⁴  Department of Entomology, Virginia Tech University, Blacksburg, VA 24061, USA

⁵  Division of Biology, Imperial College London, Ascot, Berkshire SL5 7PY, UK

author email corresponding author email

Malaria Journal 2007, 6:87doi:10.1186/1475-2875-6-87

Published:	6 July 2007

Abstract

Background

Genetic linkage mapping identified a region of chromosome 2L in the Anopheles gambiae genome that exerts major control over natural infection by Plasmodium falciparum. This 2L Plasmodium-resistance interval was mapped in mosquitoes from a natural population in Mali, West Africa, and controls the numbers of P. falciparum oocysts that develop on the vector midgut. An important question is whether genetic variation with respect to Plasmodium-resistance exists across Africa, and if so whether the same or multiple geographically distinct resistance mechanisms are responsible for the trait.

Methods

To identify P falciparum resistance loci in pedigrees generated and infected in Kenya, East Africa, 28 microsatellite loci were typed across the mosquito genome. Genetic linkage mapping was used to detect significant linkage between genotype and numbers of midgut oocysts surviving to 7–8 days post-infection.

Results

A major malaria-control locus was identified on chromosome 2L in East African mosquitoes, in the same apparent position originally identified from the West African population. Presence of this resistance locus explains 75% of parasite free mosquitoes. The Kenyan resistance locus is named EA_Pfin1 (East Africa_ Plasmodium falciparum Infection Intensity).

Conclusion

Detection of a malaria-control locus at the same chromosomal location in both East and West African mosquitoes indicates that, to the level of genetic resolution of the analysis, the same mechanism of Plasmodium-resistance, or a mechanism controlled by the same genomic region, is found across Africa, and thus probably operates in A. gambiae throughout its entire range.