C-Type Lectin-20 Interacts with ALP1 Receptor to Reduce Cry Toxicity in Aedes aegypti.

Khadija Batool,Xiong Guan,Lingling Zhang,Guohui Zhao,Enjiong Huang,Junxiang Wang,Intikhab Alam,Xiaoqiang Yu,Jin Xu

doi:10.3390/toxins10100390

Abstract

Aedes aegypti is a crucial vector for human diseases, such as yellow fever, dengue, chikungunya, and Zika viruses. Today, a major challenge throughout the globe is the insufficient availability of antiviral drugs and vaccines against arboviruses, and toxins produced by Bacillus thuringiensis (Bt) are still used as biological agents for mosquito control. The use of Cry toxins to kill insects mainly depends on the interaction between Cry toxins and important toxin receptors, such as alkaline phosphatase (ALP). In this study, we investigated the function of A. aegypti C-type lectin-20 (CTL-20) in the tolerance of Cry toxins. We showed that recombinant CTL-20 protein interacted with both Cry11Aa and ALP1 by the Far-Western blot and ELISA methods, and CTL-20 bound to A. aegypti larval brush border membrane vesicles (BBMVs). Binding affinity of CTL-20 to ALP1 was higher than that of Cry11Aa to ALP1. Furthermore, the survival rate of A. aegypti larvae fed with Cry11Aa toxin mixed with recombinant CTL-20 fusion protein was significantly increased compared with that of the control larvae fed with Cry11Aa mixed with thioredoxin. Our novel results suggest that midgut proteins like CTLs may interfere with interactions between Cry toxins and toxin receptors by binding to both Cry toxins and receptors to alter Cry toxicity.

Highlights

The mosquito Aedes aegypti is one of the serious diseases-causing vectors, closely associated with tropical areas of the world and native to Africa [1]
The result revealed that C-type lectin-20 (CTL-20) of A. aegypti was closely clustered with Culex mosquito C-type lectins (CTLs)
These results suggest that CTL-20 can bind to ALP1, one of ALP1, the Cryone receptors, but receptors, and to Cry11Aa toxin

Summary

Introduction

The mosquito Aedes aegypti is one of the serious diseases-causing vectors, closely associated with tropical areas of the world and native to Africa [1]. A. aegypti transmits rapidly emerging arboviruses, including yellow fever, dengue [2], chikungunya, and Zika viruses that spread widely throughout the world [3,4,5,6]. During the last 40 years, there has been an alarming increase of dengue virus of almost 30-fold, recorded in 90 countries including Australia, Southern Europe, and United States [10]. Toxins 2018, 10, 390 insufficient availability of antiviral drugs and vaccines against the arbovirus, the main approach for controlling mosquito-borne diseases is still through vector control. The key steps for formation of Cry toxin pores in the plasma membrane of midgut cells that cause cell death include the following: (1) protoxin solubilization, (2) protoxin proteolytic activation by specific proteases, (3) interaction between active toxins and putative receptors,

Methods

Results

Conclusion