Cultivable Bacterial Diversity in the Gut of the Chagas Disease Vector Triatoma dimidiata: Identification of Possible Bacterial Candidates for a Paratransgenesis Approach

Teresa Lopez-Ordonez,Rene Montejo-Lopez,Andres Cruz-Hernandez,Carlos A Flores-López,Erin E Conners

doi:10.3389/fevo.2017.00174

Abstract

Since bacterial symbionts play a vital role in the metabolism of hematophagous insect vectors the method known as paratrangenesis, which consists of the use of cultivable insect symbionts to interfere with the transmission of vector-transmitted pathogens has been shown to be effective in certain vector control oriented studies. In Chagas disease research a recent study introduced transgenes through a parastransgenic approach and prevented the development of a vector species for this disease. However this approach requires a previous characterization of the bacterial symbionts present in the species vector of interest, since a selection of the cultivable bacterial symbiont used is mandatory. In this study, we describe the gut bacterial diversity of Triatoma dimidiata specimens from Southern Mexico. Bacteria from both wild and laboratory-reared specimens were cultured, and resulting colonies were grown individually, harvested, and subsequently identified by 16S ribosomal loci sequencing. A total of five and three genera and a total of nine and six bacterial species were identified from field captured and laboratory reared Triatoma dimidiata specimens respectively. A majority of Gram positive bacteria were identified, which included the genera Staphylococcus, Bacillus, Brevibacterium, Micrococcus and Delftia. Given previous studies we propose the use of Staphylococcus saprophyticus, Micrococcus luteus and Bacillus megaterium as potential candidates for future paratransgenic efforts done with Triatoma dimidiata, which is one of the most important vectors of Chagas disease, in Central and South America. Given the vital association bacterial symbionts play in the metabolism of routes of hematophagous insect vectors Paratransgenesis consists of the use of cultivable insect symbionts to interfere with the transmission of vector-transmitted pathogens.

Highlights

The World Health Organization has estimated Chagas disease affects about 6–7 million people worldwide, while 100 million people are at risk of acquiring the disease in the Americas
YX3, S. saprophyticus, S. saprophyticus subsp. bovis, Staphylococcus nepalensis, Staphylococcus hominis, and Staphylococcus lentus), while the other three Firmicutes isolates had their most significant sequence identity hit to the Bacillus genera
Two of the isolates had their most significant sequence identity hit to Brevibacterium avium and Brevibacterium iodinum, while the other isolate had its most significant sequence identity hit in Micrococcus luteus

Summary

Introduction

The World Health Organization has estimated Chagas disease affects about 6–7 million people worldwide, while 100 million people are at risk of acquiring the disease in the Americas. The main form of parasite transmission to humans is through the contact with the feces of blood-sucking triatomine bugs (WHO, 2015). The cost associated with the manufacture of environmentally damaging chemicals which can be used as insecticides is usually very high for developing countries. This high cost is one of the main reasons developing countries interrupt vector control programs, including those for Chagas disease. Understanding some bionomic aspects of the triatomine insects can inform the design of better control programs to interrupt transmission of the parasite (Ramsey and Schofield, 2003)

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