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A calcium-activated nucleotidase secreted from Ostertagia ostertagi 4th-stage larvae is a member of the novel salivary apyrases present in blood-feeding arthropods

Published online by Cambridge University Press:  01 September 2010

D. S. ZARLENGA*
Affiliation:
USDA, ARS, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Beltsville, MD 20705, USA USDA, ARS, Animal and Natural Resources Institute, Bovine Functional Genomics Laboratory, Beltsville, MD 20705, USA
A. J. NISBET
Affiliation:
Parasitology Division, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland, UK
L. C. GASBARRE
Affiliation:
USDA, ARS, Animal and Natural Resources Institute, Bovine Functional Genomics Laboratory, Beltsville, MD 20705, USA
W. M. GARRETT
Affiliation:
USDA, ARS, Animal and Natural Resources Institute, Animal Biosciences and Biotechnology Laboratory, Beltsville, MD 20705, USA
*
*Corresponding author: US Department of Agriculture, ARS, ANRI, Animal Parasitic Diseases Lab, B1180 BARC-east, Beltsville, MD 20705, USA. Tel: 001 301 504 8754. Fax: 001 301 504 8979. E-mail: dante.zarlenga@ars.usda.gov

Summary

Apyrases (ATP-diphosphohydrolase) comprise a ubiquitous class of glycosylated nucleotidases that hydrolyse extracellular ATP and ADP to orthophosphate and AMP. One class of newly-described, Ca2+-dependent, salivary apyrases known to counteract blood-clotting, has been identified in haematophagous arthropods. Herein, we have identified a gene (Oos-apy-1) encoding a protein that structurally conforms to the Ca2+-activated apyrase from the bed bug, Cimex lectularius, by immunologically screening an Ostertagia L4 cDNA expression library. The expressed protein (rOos-APY-1) was biochemically functional in the presence of Ca2+ only, with greatest activity on ATP, ADP, UTP and UDP. Host antibodies to the fusion protein appeared as early as 14 days post-infection (p.i.) and increased through 30 days p.i. Immunohistochemical and Western blot analyses demonstrated that the native Oos-APY-1 protein is present in the glandular bulb of the oesophagus and is confined to the L4. A putative signal sequence at the N-terminus and near 100% identity with a Teladorsagia circumcincta L4 secreted protein is consistent with the native protein being secreted at the cellular level. Predicated upon substrate specificity, the native protein may be used by the parasite to control the levels of host extracellular nucleotides released by locally-damaged tissues in an effort to modulate immune intervention and inflammation.

Information

Type
Research Article
Copyright
Copyright © Cambridge University Press 2010

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