This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Duffy, M. S. Articles by Appleton, J. A. Search for Related Content PubMed PubMed Citation Articles by Duffy, M. S. Articles by Appleton, J. A.

 Previous Article  |  Next Article 

Infection and Immunity, February 2006, p. 1297-1304, Vol. 74, No. 2
0019-9567/06/$08.00+0     doi:10.1128/IAI.74.2.1297-1304.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Cathepsin B Homologue at the Interface between a Parasitic Nematode and Its Intermediate Host

James A. Baker Institute for Animal Health,¹ Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853,³ Bovine Functional Genomics Laboratory, USDA, ARS, ANRI, Bldg. 1180, BARC-East, Beltsville, Maryland 20705²

Received 16 August 2005/ Returned for modification 17 September 2005/ Accepted 23 November 2005

Parelaphostrongylus tenuis is a parasitic nematode that causes a debilitating neurologic disease in many North American cervids and domestic livestock species. We produced a PCR-based cDNA library from infective larvae (L3) in order to identify molecules that mediate parasitism. A dominant 1,250-bp amplicon encoded a homologue of cathepsin B cysteine proteases. The sequence incorporated a C29G substitution in the putative active site. Antibodies generated against a recombinant form detected the native protein (PtCPR-1) in Western blot assays of L3, but not adult worm, extracts. Immunohistochemical methods revealed that PtCPR-1 synthesis was restricted to larval stages within the snail intermediate host (Triodopsis sp.), beginning as early as 2 days postinfection (dpi) of snails. The protein was present in the intestine and luminal contents and was lost from larvae over time. Concurrent studies showed that larvae induced an immune response in snails beginning at 1 dpi. Layers of hemocytes encapsulated larvae immediately after infection, and granuloma-like structures formed around parasites in chronic infections. Loss of PtCPR-1 from L3 and its accumulation in host tissues coincided with degeneration of granuloma architecture 90 to 105 dpi. Fully developed L3 emerged from the snail at this time. Our data implicate PtCPR-1 in larval development and possibly in the emergence of P. tenuis from the intermediate host. Emerged L3 survived desiccation and cold stress, suggesting that they could remain infectious in the environment. Molecules promoting emergence would facilitate dispersal of L3 and increase the likelihood of transmission to definitive hosts.

Editor: W. A. Petri, Jr.

This article has been cited by other articles:

• Duffy, M. S., Morris, H. R., Dell, A., Appleton, J. A., Haslam, S. M. (2006). Protein glycosylation in Parelaphostrongylus tenuis--first description of the Gal{alpha}1-3Gal sequence in a nematode. Glycobiology 16: 854-862 [Abstract] [Full Text]