Submitted to: American Association of Veterinary Parasitologists
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2007
Publication Date: July 14, 2007
Citation: Zarlenga, D.S., Gasbarre, L.C. 2007. A tgf-b homologue identified from ascaris suum 4th stage larvae (l4): evidence for development-related transcription and incomplete gene splicing. American Association of Veterinary Parasitologists. pp. 130
Ascaris species represent the most prevalent parasitic worm infecting humans and swine worldwide. During the infection process, A. suum L4 establish in the jejunum and develop into adults. However, a large percentage of L4 spontaneously cure to the ileum at 14 to 21 days after inoculation (dpi), and are eventually expelled from the intestine. An elevation in the expression of genes for structural proteins related to parasite vigor was previously detected by cDNA microarray analysis in the population of L4 that remained in the jejunum. From this cDNA library, a bank of L4-derived ESTs were generated, sequenced, and a putative TGF-B homologue was identified and characterized by sequence similarity to the Tgh-1 gene of Brugia malayi and the TGF-B-like growth factor from Caenorhabditis elegans. Sequence information uncovered at least 2 differently-spliced transcripts, one likely derived from incompletely-spliced heteronuclear RNA. Quantitative PCR analysis revealed peak transcript levels coincident with periods of rapid growth during embryonation, and at 7 and 14 dpi. Differential expression was also identified in populations of L4 isolated from either the jejunum or ileum at 21 dpi. These data support a relationship between expression of the Tgh-1 and parasite development, and avoidance of spontaneous cure.