Secreted venom allergen-like proteins of helminths: Conserved modulators of host responses in animals and plants.

Ruud H P Wilbers,Oluwatoyin A Asojo,Claire Drurey,Jose L Lozano-Torres,Roger Schneiter,Geert Smant,Martijn H M Holterman,Rick M Maizels,James B Lok

doi:10.1371/journal.ppat.1007300

Abstract

Despite causing considerable damage to host tissue at the onset of parasitism, invasive helminths establish remarkably persistent infections in both animals and plants. Secretions released by these obligate parasites during host invasion are thought to be crucial for their persistence in infection. Helminth secretions are complex mixtures of molecules, most of which have unknown molecular targets and functions in host cells or tissues. Although the habitats of animal- and plant-parasitic helminths are very distinct, their secretions share the presence of a structurally conserved group of proteins called venom allergen-like proteins (VALs). Helminths abundantly secrete VALs during several stages of parasitism while inflicting extensive damage to host tissue. The tight association between the secretion of VALs and the onset of parasitism has triggered a particular interest in this group of proteins, as improved knowledge on their biological functions may assist in designing novel protection strategies against parasites in humans, livestock, and important food crops.

Highlights

Upon infection, helminth parasites establish an intricate relationship with their host
Helminth venom allergen-like proteins (VALs) are classified as SCP/TAPS proteins, which include a range of structurally related proteins found in a wide range of eukaryotes [5]
These findings suggest that stylet-secreted VALs are important for modulating host responses, during the migration of the nematodes through host tissues and the early stages of an infection

Summary

Introduction

Helminth parasites establish an intricate relationship with their host. Recent reports have shed new light on structural properties, biochemical modes of action, and functions of secreted VALs of parasitic helminths Most of these reports have been published in specialized journals dedicated to either medical and veterinary biology or plant pathology. Modelling the evolutionary history of nematode VALs, based on overall sequence diversity, may reveal links between patterns of diversification within this protein family and particular lifestyles or host organisms. To this end, we generated a Bayesian tree of available VAL sequences from plant- and animal-parasitic nematodes as well as their free-living close relatives from the distal end of the nematode tree (Fig 1 and S1 Fig, S1 Table) [10]. Our phylogenetic analysis revealed no clear link between overall sequence diversity in VAL genes in nematodes and parasitism in plant and animals

Helminth VALs bind lipids and other hydrophobic structures

Biological functions of VALs from plant parasites

Biological functions of VALs from animal parasites

Concluding paragraph

Findings

Supporting information