Open Access Research

First analysis of the secretome of the canine heartworm, Dirofilaria immitis

James Geary1, Mohamed Satti14, Yovany Moreno25, Nicole Madrill1, Doug Whitten3, Selwyn A Headley46, Dalen Agnew1, Timothy Geary2 and Charles Mackenzie1*

Author Affiliations

1 Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA

2 Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada

3 Department of Plant Science, Michigan State University, East Lansing, MI 48824, USA

4 School of Veterinary Medicine, St Mathew’s University, Orlando, Grand Cayman

5 Harvard School of Public Health, Boston, MA 02115, USA

6 Current address: Laboratory of Veterinary Pathology, Faculty of Veterinary Medicine, Universidade Norte do Paraná, Arapongas, PR, Brazil

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Parasites & Vectors 2012, 5:140  doi:10.1186/1756-3305-5-140

Published: 10 July 2012

Abstract

Background

The characterization of proteins released from filariae is an important step in addressing many of the needs in the diagnosis and treatment of these clinically important parasites, as well as contributing to a clearer understanding of their biology. This report describes findings on the proteins released during in vitro cultivation of adult Dirofilaria immitis , the causative agent of canine and feline heartworm disease. Differences in protein secretion among nematodes in vivo may relate to the ecological niche of each parasite and the pathological changes that they induce.

Methods

The proteins in the secretions of cultured adult worms were run on Tris-Glycine gels, bands separated and peptides from each band analysed by ultra mass spectrometry and compared with a FastA dataset of predicted tryptic peptides derived from a genome sequence of D. immitis.

Results

This study identified 110 proteins. Of these proteins, 52 were unique to D. immitis . A total of 23 (44%) were recognized as proteins likely to be secreted. Although these proteins were unique, the motifs were conserved compared with proteins secreted by other nematodes.

Conclusion

The present data indicate that D. immitis secretes proteins that are unique to this species, when compared with Brugia malayi. The two major functional groups of molecules represented were those representing cellular and of metabolic processes. Unique proteins might be important for maintaining an infection in the host environment, intimately involved in the pathogenesis of disease and may also provide new tools for the diagnosis of heartworm infection.

Keywords:
Dirofilaria; Heartworm; Canine; Feline; Nematode; Filarial; Secretome; Proteins