Positive selection drives accelerated evolution of mosquito salivary genes associated with blood-feeding

Authors

  • B. Arcà,

    1. Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Roma, Italy
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    • These authors participated equally in this work.
  • C. J. Struchiner,

    1. Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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    • These authors participated equally in this work.
  • V. M. Pham,

    1. Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
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  • G. Sferra,

    1. Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Roma, Italy
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  • F. Lombardo,

    1. Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Roma, Italy
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  • M. Pombi,

    1. Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Roma, Italy
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  • J. M. C. Ribeiro

    Corresponding author
    1. Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
    • Correspondence: José M. C. Ribeiro, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, 12735 Twinbrook Parkway Room 2E32D, Rockville, MD 20852, USA. Tel.: +1 301 496 9389; fax: +1 301 480 2571; e-mail: jribeiro@niaid.nih.gov

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Abstract

The saliva of bloodsucking animals contains dozens to hundreds of proteins that counteract their hosts’ haemostasis, inflammation and immunity. It was previously observed that salivary proteins involved in haematophagy are much more divergent in their primary sequence than those of housekeeping function, when comparisons were made between closely related organisms. While this pattern of evolution could result from relaxed selection or drift, it could alternatively be the result of positive selection driven by the intense pressure of the host immune system. We investigated the polymorphism of five different genes associated with blood-feeding in the mosquito Anopheles gambiae and obtained evidence in four genes for sites with signatures of positive selection. These results add salivary gland genes from bloodsucking arthropods to the small list of genes driven by positive selection.

Ancillary