Detection of diverse Wolbachia 16S rRNA sequences at low titers from malaria vectors in Kayin state, Myanmar.

Sunisa Sawasdichai,Tee Dah,Nicholas J White,Victor Chaumeau,Monthicha Phanaphadungtham,Muesuwa Trakoolchengkaew,Gilles Delmas,Kyi Oo,François H Nosten,Thithiworada Kulabkeeree,Praphan Kittiphanakun,Yanada Akararungrot,Ladda Kajeechiwa

doi:10.12688/wellcomeopenres.15005.4

Abstract

Background : Natural Wolbachia infections in malaria mosquitoes were recently reported in Africa, and negatively correlated with the development of Plasmodium falciparum in the vectors. The occurrence and effects of Wolbachia infections outside Africa have not been described and may have been underestimated. Methods : Mosquitoes were collected by human-landing catch during May and June 2017 in ten villages in Kayin state, Myanmar. Closely related species of malaria vectors were identified with molecular assays. 16S rRNA Wolbachia DNA sequences were detected with quantitative real-time PCR. Results: Low titer of Wolbachia DNA was detected in 13/370 samples in six malaria vector species. Sequences were diverse and different from those described in the African malaria mosquitoes. Conclusion: The detection of Wolbachia DNA in malaria mosquitoes from Kayin state warrants further investigations to understand better the ecology and biology of Anopheles- Wolbachia interactions in Southeast Asia.

Highlights

The authors state that cytoplasmic incompatibility (CI) ‘enhances the “vertical” transmission of Wolbachia’
Results qPCR assay validation for the detection of Wolbachia in mosquitoes Optimal reaction conditions were similar for both primer sets: 58°C for primer annealing, 2.5 mM of MgCl and 200 nM of each primers
We report the occurrence of 12 Anopheles taxa among which nine were groups of closely related or sibling species (Maculatus, Funestus, Jamesii, Leucosphyrus, Annularis, Barbirostris, Subpictus, Hyrcanus and Asiaticus Groups) and only three were sensu stricto species (An. karwari, An. kochi and An. tessellatus)

Summary

Introduction

The authors state that cytoplasmic incompatibility (CI) ‘enhances the “vertical” transmission of Wolbachia’. The authors state that ‘Shaw et al observed a negative correlation between Wolbachia infection and the development of P. falciparum oocysts in naturally blood-fed females’. This is not completely correct, as in this work the authors have quantified the prevalence of P. falciparum in resting blood fed females inside house 5 days after collection/blood feeding, without any prior knowledge on the infectious status of the mosquitoes; thereby, the stage of parasite infection (oocyst or sporozoite) was not investigated. The paragraph describing natural Wolbachia infections in mosquitoes needs further references[1,2,3]. Natural Wolbachia infections in malaria mosquitoes were recently reported in Africa, and negatively correlated with the development of Plasmodium falciparum in the vectors. Sequences were diverse and different from those described in the African malaria mosquitoes

Objectives

Methods

Results

Discussion

Conclusion