Plasmodium infection upregulates prophenoloxidase (AcPPO6A) in Anopheles culicifacies

Janneth Rodrigues, Anil Sharma, Mayur Kajla, Neema Agrawal, T. Adak and Raj K. Bhatnagar

volume 1 | issue 1

Jannuary/February 2009

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Anopheles culicifacies is the main vector for transmission of Plasmodium vivax malaria in the Indian sub-continent. A strain of A. culicifacies isolated from its natural niche displayed complete refractoriness to P. vivax by melanotic encapsulation of ookinetes. Prophenoloxidases are key components of the phenoloxidase (PO) cascade that leads to recognition and melanization of invading organisms. We isolated and cloned prophenoloxidase-encoding AcPPO6A gene from the body tissue of A. culicifacies and analyzed its expression profile under various regimens of immune challenge. The transcript levels of the AcPPO6A gene were higher in naïve adult refractory female mosquitoes as compared to female susceptible mosquitoes. AcPPO6A was differentially expressed during various stages of larval development. The expression pattern of the gene was monitored in refractory and susceptible strains temporally in response to injury, challenge with bacteria and Plasmodium vinckei petteri parasite. The AcPPO6A transcription was upregulated in response to bacteria and parasite challenge exclusively in refractory strain suggestive of its role in effectuating a melanotic response in Plasmodium-incompetent naturally occurring refractory culicifacies strains.

Authors

Janneth Rodrigues

International Centre for Genetic Engineering and Biotechnology (ICGEB); National Institutes for Health

Anil Sharma

International Centre for Genetic Engineering and Biotechnology (ICGEB); National Institute of Malaria Research

Mayur Kajla

University of Wisconsin-Madison

Neema Agrawal

International Centre for Genetic Engineering and Biotechnology (ICGEB)

T. Adak

National Institute of Malaria Research

Raj K. Bhatnagar