Email updates

Keep up to date with the latest news and content from Parasites & Vectors and BioMed Central.

Open Access Highly Accessed Research

Localization of Wolbachia-like gene transcripts and peptides in adult Onchocerca flexuosa worms indicates tissue specific expression

Samantha N McNulty1*, Kerstin Fischer1, Kurt C Curtis1, Gary J Weil1, Norbert W Brattig2 and Peter U Fischer1

Author Affiliations

1 Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO, 63110, USA

2 Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany

For all author emails, please log on.

Parasites & Vectors 2013, 6:2  doi:10.1186/1756-3305-6-2

Published: 2 January 2013

Abstract

Background

Most filarial species in the genus Onchocerca depend on Wolbachia endobacteria to successfully carry out their life cycle. O. flexuosa is a Wolbachia-free species, but its genome contains Wolbachia-like sequences presumably obtained from Wolbachia via horizontal gene transfer. Proteogenomic studies have shown that many of these Wolbachia-like sequences are expressed in adult worms.

Methods

Six Wolbachia-like sequences in O. flexuosa were chosen for further study based on their sequence conservation with Wolbachia genes, length of predicted open reading frames, and expression at the RNA and/or protein levels. In situ hybridization and immunohistochemical labeling were used to localize Wolbachia-like transcripts and peptides in adult worm tissues.

Results

RNA probes representing three of the six target sequences produced hybridization signals in worm tissues. These probes bound to transcripts in the intestine and lateral chords of both sexes, in the hypodermis, median chords and uteri in females, and in sperm precursor cells in males. Antibodies raised to three peptides corresponding to these transcripts bound to specific bands in a soluble extract of adult O. flexuosa by Western blot that were not labeled by control antibodies in pre-immune serum. Two of the three antibodies produced labeling patterns in adult worm sections that were similar to those of the RNA probes, while the third produced a different pattern.

Conclusions

A subset of the Wolbachia-like sequences present in the genome of the Wolbachia-free filarial species O. flexuosa are transcribed in tissues where Wolbachia reside in infected filarial species. Some of the peptides and/or proteins derived from these transcripts appear to be concentrated in the same tissues while others may be exported to other regions of the worm. These results suggest that horizontally transferred Wolbachia genes and gene products may replicate important Wolbachia functions in uninfected filarial worms.

Keywords:
Filariasis; horizontal gene transfer; in situ hybridization; immunohistology; Wolbachia