Open Access Research article

Extensively duplicated and transcriptionally active recent lateral gene transfer from a bacterial Wolbachia endosymbiont to its host filarial nematode Brugia malayi

Panagiotis Ioannidis15, Kelly L Johnston2, David R Riley1, Nikhil Kumar1, James R White1, Karen T Olarte1, Sandra Ott1, Luke J Tallon1, Jeremy M Foster3, Mark J Taylor2 and Julie C Dunning Hotopp14*

Author Affiliations

1 Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA

2 Liverpool School of Tropical Medicine, Liverpool, UK

3 New England Biolabs, Ipswich, MA, USA

4 Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA

5 Current address: Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland

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BMC Genomics 2013, 14:639  doi:10.1186/1471-2164-14-639

Published: 22 September 2013



Lymphatic filariasis is a neglected tropical disease afflicting more than 120 million people, while another 1.3 billion people are at risk of infection. The nematode worm Brugia malayi is one of the causative agents of the disease and exists in a mutualistic symbiosis with Wolbachia bacteria. Since extensive lateral gene transfer occurs frequently between Wolbachia and its hosts, we sought to measure the extent of such LGT in B. malayi by whole genome sequencing of Wolbachia-depleted worms.


A considerable fraction (at least 115.4-kbp, or 10.6%) of the 1.08-Mbp Wolbachia wBm genome has been transferred to its nematode host and retains high levels of similarity, including 227 wBm genes and gene fragments. Complete open reading frames were transferred for 32 of these genes, meaning they have the potential to produce functional proteins. Moreover, four transfers have evidence of life stage-specific regulation of transcription at levels similar to other nematode transcripts, strengthening the possibility that they are functional.


There is extensive and ongoing transfer of Wolbachia DNA to the worm genome and some transfers are transcribed in a stage-specific manner at biologically relevant levels.