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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Microbiol. | doi: 10.3389/fmicb.2019.01580

A gut symbiotic bacterium Serratia marcescens renders mosquito resistance to Plasmodium infection through activation of mosquito immune responses

  • 1Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences (CAS), China
  • 2School of Life Sciences and Technology, Tongji University, China
  • 3Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases (NIH), United States

The malaria development in the mosquito midgut is a complex process that results in considerable parasite losses. The mosquito gut microbiota influences the outcome of pathogen infection in mosquitoes, but the underlying mechanisms through which gut symbiotic bacteria affect vector competence remain elusive. Here, we identified two Serratia strains (Y1 and J1) isolated from field-caught female Anopheles sinensis from China and assessed their effect on Plasmodium development in An. stephensi. Colonization of An. stephensi midgut by Serratia Y1 significantly renders the mosquito resistant to Plasmodium berghei infection, while Serratia J1 has no impact on parasite development. Parasite inhibition by Serratia Y1 is induced by the activation of the mosquito immune system. Genome-wide transcriptomic analysis by RNA-seq shows a similar pattern of midgut gene expression in response to Serratia Y1 and J1 in sugar-fed mosquitoes. However, 24 h after blood ingestion, Serratia Y1 modulates more midgut genes than Serratia J1 including the c-type lectins (CTLs), CLIP serine proteases and other immune effectors. Furthermore, silencing of several Serratia Y1-induced anti-Plasmodium factors like the thioester-containing protein 1 (TEP1), fibrinogen immunolectin 9 (FBN9) or leucine-rich repeat protein LRRD7 can rescue parasite oocyst development in the presence of Serratia Y1, suggesting that these factors modulate the Serratia Y1-mediated anti-Plasmodium effect. This study enhances our understanding of how gut bacteria influence mosquito-Plasmodium interactions.

Keywords: Anopheles mosquito, Gut symbiont, antiparasitic defense, malaria transmission, immune activation

Received: 15 Mar 2019; Accepted: 25 Jun 2019.

Edited by:

Rhoel Dinglasan, Emerging Pathogens Institute, University of Florida, United States

Reviewed by:

Isabelle Morlais, Institut de recherche pour le développement (IRD), France
Sandrine E. Nsango, University of Douala, Cameroon
Mathilde Gendrin, Institut Pasteur de la Guyane, French Guiana  

Copyright: © 2019 Wang, Bai, Wang, Vega-Rodríguez and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Sibao Wang, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences (CAS), Shanghai, China, sbwang@sibs.ac.cn