Proteomics Analysis of the Excretory/Secretory Component of the Blood-feeding Stage of the Hookworm, Ancylostoma caninum

Abstract

Hookworms are blood-feeding intestinal parasites of mammalian hosts and are one of the major human ailments affecting ϳ600 million people worldwide. These parasites form an intimate association with the host and are able to avoid vigorous immune responses in many ways including skewing of the response phenotype to promote parasite survival and longevity. The primary interface between the parasite and the host is the excretory/secretory component, a complex mixture of proteins, carbohydrates, and lipids secreted from the surface or oral openings of the parasite. The composition of this complex mixture is for the most part unknown but is likely to contain proteins important for the parasitic lifestyle and hence suitable as drug or vaccine targets. Using a strategy combining the traditional technology of one-dimensional SDS-PAGE and the newer fractionation technology of OFFGEL electrophoresis we identified 105 proteins from the excretory/secretory products of the blood-feeding stage of the dog hookworm, Ancylostoma caninum. Highly represented among the identified proteins were lectins, including three C-type lectins and three ␤-galactoside-specific S-type galectins, as well as a number of proteases belonging to the three major classes found in nematodes, aspartic, cysteine, and metalloproteases. Interestingly 28% of the identified proteins were homologous to activation-associated secreted proteins, a family of cysteine-rich secreted proteins belonging to the sterol carrier protein/Tpx-1/Ag5/ PR-1/Sc-7 (TAPS) superfamily. Thirty-four of these proteins were identified suggesting an important role in host-parasite interactions. Other protein families identified included hyaluronidases, lysozyme-like proteins, and transthyretin-like proteins. This work identified a suite of proteins important for the parasitic lifestyle and provides new insight into the biology of hookworm infection.

A Deep Exploration of the Transcriptome and “Excretory/Secretory” Proteome of Adult Fascioloides magna

“…In particular, a significant proportion of nonclassically secreted ES proteins, including a number of proteins predicted to be membrane bound, such as a tetraspanin and a glucose transporter, were identified. Unlike ES products from gastrointestinal parasitic nematodes, such as Ancylostoma caninum (31), in which classically secreted proteins are very abundant, nonclassically secreted proteins have been consistently shown to represent a significant proportion of ES products from trematode parasites, including S. japonicum (79), C. sinensis (67), O. viverrini (68), and Fa. hepatica (66).…”

Excretory/Secretory Proteome of the Adult Developmental Stage of Human Blood Fluke, Schistosoma japonicum

“…However, the latter was repeatedly detected in the various ESPs from different parasites, including Ancylostoma caninum (25), Teladorsagia circumcincta (26), and S. mansoni (35), suggesting that such proteins are purposely released by parasites through an unknown excretory mechanism. Some ES proteins were predicted as non-secreted possibly due to N-terminal sequence truncations, which are common in EST clusters assembled with 3Ј-mRNA-enriched ESTs (41,42).…”

“…Importantly this information can be expected to facilitate the discovery of vaccines and new therapeutic drug targets as well as new diagnostic reagents for schistosomiasis control. Proteomics approaches encompass the most efficient and powerful tools for identification of protein complexes and have been widely used to decipher the ES components of the filarial parasite Brugia malayi (19), Leishmania (Trypanosomatidae) (20), nematodes (21)(22)(23)(24)(25)(26), and Trematoda (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37). For the genus Schistosoma, the ES compositions of S. mansoni have been identified in many developmental life stages, including sporocyst (34), cercaria (35,36), and egg (37) but have not been characterized in the adult worm.…”

Probing the equatorial groove of the hookworm protein and vaccine candidate antigen, Na-ASP-2

“…Such efforts require an improved knowledge of hookworm disease on the molecular and immunological levels, and, more specifically, the pathogen-host interactions. In this context, previous studies have suggested a prominent role for activation-associated proteins (ASPs) which are amongst the ten most abundant groups of proteins in hookworms (Cantacessi et al, 2009) and the major constituents of the excretory/secretory (ES) proteins released by the blood-feeding adult stage hookworms (Mulvenna et al, 2009). ASPs belong to a large group of proteins called the 'sperm-coating protein (SCP)-like extracellular proteins', also known as SCP/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS; Pfam accession no PF00188).…”