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A calcium‐activated apyrase from Teladorsagia circumcincta : an excretory/secretory antigen capable of modulating host immune responses?
Author(s) -
NISBET A. J.,
ZARLENGA D. S.,
KNOX D. P.,
MEIKLE L. I.,
WILDBLOOD L. A.,
MATTHEWS J. B.
Publication year - 2011
Publication title -
parasite immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 75
eISSN - 1365-3024
pISSN - 0141-9838
DOI - 10.1111/j.1365-3024.2011.01278.x
Subject(s) - apyrase , teladorsagia circumcincta , biology , ostertagia ostertagi , nucleoside triphosphate , recombinant dna , complementary dna , biochemistry , immune system , microbiology and biotechnology , enzyme , immunology , gene , nucleotide , helminths , haemonchus contortus
Summary A cDNA representing the gene Teladorsagia circumcincta apyrase‐1 (Tci‐apy‐1) was isolated, by PCR, from a T. circumcincta fourth‐stage larval (L4) cDNA library. The closest orthologue of this gene is a Ca 2+ ‐dependent apyrase from Ostertagia ostertagi, with 92% amino acid identity across all 339 residues. Tci‐apy‐1 is transcribed in a stage‐specific manner, the transcript being predominant in L4, detectable in the adult cDNA, but absent from eggs and infective third‐stage larvae (L3). The protein, Tci‐APY‐1, was detected by immunoblotting in extracts of L4 nematodes and was present in excretory/secretory products from the same developmental stage. A recombinant version of Tci‐APY‐1 was expressed in bacteria as an active enzyme that hydrolysed nucleoside triphosphate substrates with a preference of ATP over other nucleoside triphosphates. Recombinant Tci‐APY‐1 hydrolysed ATP and ADP but not AMP. Apyrase activity was divalent cation‐dependent, with no hydrolysis in the presence of Mg 2+ , but activation in the presence of Ca 2+ . Recombinant Tci‐APY‐1 was bound by IgG present in serum and both IgG and IgA present in abomasal mucus from trickle‐infected, immune sheep but not in material derived from lambs exposed to a single infection. The potential immunomodulatory roles of this Tci‐APY‐1 are discussed in relation to purinergic signalling.