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Research Project:
STRATEGIES TO CONTROL SWINE PARASITES AFFECTING FOOD SAFETY
Location: Animal Parasitic Diseases
Title: Identification and Partial Characterization of a Cdna Sequence Encoding a Glutamic Acid-Rich Protein Specifically Transcribed in Trichinella Spiralis Newborn Larvae and Recognized by Swine Infection Serum.
Authors
Submitted to: International Journal for Parasitology
Publication Type:
Peer Reviewed Journal
Publication Acceptance Date: June 30, 2002
Publication Date: August 15, 2002
Citation: Zarlenga, D.S., Boyd, P., Lichtenfels, J.R., Hill, D.E., Gamble, H.R. 2002. Identification and partial characterization of a cdna sequence encoding a glutamic acid-rich protein specifically transcribed in trichinella spiralis newborn larvae and recognized by swine infection serum. International Journal for Parasitology.
Interpretive Summary: A recent review indicates that trichinellosis is both an emerging
as well as reemerging disease whereby the incidence derived from
sylvatic sources is on the rise in both developing and developed
countries. Infections from domestic pork continue to rise in
Asia, East and Central Europe and South America, where the
prevalence in swine herds can reach as high as 50%. Presently,
little is known of the mechanisms by which intracellular
parasites penetrate and reprogram cells to protect themselves
from the host immune system without compromising the viability of
the cell. Understanding one or more of these mechanisms has far
reaching implications in both Agricultural and human research. To
this end, a library was constructed from the T. spiralis newborn
larvae and screened for sequences specific to this stage. One
group of clones was identified encoding a glutamic acid rich
family of proteins where similarly characterized proteins from
protozoan parasites have been linked to cell membrane attachment
and the infection process. This is the first report of
identifying gene products that maybe associated with the
infection process within parasitic nematodes. Given that state-
of-the-art investigations on xenotransplantation use swine as the
donor host for organs, and that degenerative muscle diseases have
received a high degree of attention in recent years, delineating
changes in gene expression associated with muscle atrophy will
assist not only in comprehending mechanisms involved in parasite
invasion of the cell, but may serve also as a model for animal
and human degenerative muscle diseases.
Technical Abstract: A PCR-derived cDNA expression library was constructed using 0.5 ug of total RNA from T. spiralis newborn larvae (NBL). The library consisted of >125,000 insert-containing clones. Approximately 40-50 x 103 clones were screened immunologically using sera from pigs experimentally infected with 7000 Trichinella L1. Multiple clones reacting positively with the swine infection serum and encoding portions of a glutamic acid-rich (GAR) protein were identified. Northern and Southern blots indicated at least 2 distinct genes that encoded for the GAR proteins and that these genes were transcribed specifically in the NBL stage. cDNA sequence data predicted open reading frames of 1497 bp (NBL1500) and 1716 bp (NBL1700) generating proteins of 498 aa and 571 aa, respectively. Both sequences consisted of approximately 39% glutamic acid and 16% serine residues, and differed by the presence of a 219 bp fragment present in the 1716 bp sequence that was absent from the 1497 bp sequence. PCR data indicated that additional isoforms exist within this gene family that are different in length form those described above. In
addition, it was found that more than one isoform can exist within a single worm and that this pattern can vary between individual worms within a population. Mouse antibodies to recombinant antigen localized the GAR proteins to the periphery of the developing stichocyte cells within the NBL.
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Last Modified: 03/16/2009
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