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Open Access Research

Alternative splicing of the Anopheles gambiae Dscam gene in diverse Plasmodium falciparum infections

Paul H Smith1*, Jonathan M Mwangi2, Yaw A Afrane3, Guiyun Yan4, Darren J Obbard1, Lisa C Ranford-Cartwright2 and Tom J Little1

Author Affiliations

1 Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, EH9 3JT Edinburgh, UK

2 Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ Glasgow, UK

3 Centre for Vector Biology and Control Research, Kenya Medical Research Institute, Mumias Rd, Kisumu, Kenya

4 Program in Public Health, University of California at Irvine, Irvine, CA 92697, USA

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Malaria Journal 2011, 10:156  doi:10.1186/1475-2875-10-156

Published: 8 June 2011

Abstract

Background

In insects, including Anopheles mosquitoes, Dscam (Down syndrome cell adhesion molecule) appears to be involved in phagocytosis of pathogens, and shows pathogen-specific splice-form expression between divergent pathogen (or parasite) types (e.g. between bacteria and Plasmodium or between Plasmodium berghei and Plasmodium falciparum). Here, data are presented from the first study of Dscam expression in response to genetic diversity within a parasite species.

Methods

In independent field and laboratory studies, a measure of Dscam splice-form diversity was compared between mosquitoes fed on blood that was free of P. falciparum to mosquitoes exposed to either single or mixed genotype infections of P. falciparum.

Results

Significant increases in Anopheles gambiae Dscam (AgDscam) receptor diversity were observed in parasite-exposed mosquitoes, but only weak evidence that AgDscam diversity rises further upon exposure to mixed genotype parasite infections was found. Finally, a cluster of AgDscam exon 4 variants that become especially common during Plasmodium invasion was identified.

Conclusions

While the data clearly indicate that AgDscam diversity increases with P. falciparum exposure, they do not suggest that AgDscam diversity rises further in response to increased parasite diversity.