Decodificado o DNA do parasita Trichinella spiralis

terça-feira, fevereiro 22, 2011

Trichinosis Parasite Gets DNA Decoded

ScienceDaily (Feb. 21, 2011) — Scientists have decoded the DNA of the parasitic worm that causes trichinosis, a disease linked to eating raw or undercooked pork or carnivorous wild game animals, such as bear and walrus.

Trichinosis is caused by eating raw or undercooked pork or carnivorous wild game animals, such as bear and walrus, infected with the parasitic worm, Trichinella spiralis. While the disease is rarely deadly, some patients live for months or years with chronic muscle pain and fatigue until the worms eventually die. (Credit: Photo by Jonathan Eisenback, Mactode Publications)

After analyzing the genome, investigators at Washington University School of Medicine in St. Louis and their collaborators report they have identified unique features of the parasite, Trichinella spiralis, which provide potential targets for new drugs to fight the illness. The research is published online Feb. 20 in Nature Genetics.

While trichinosis is no longer a problem in the United States -- fewer than a dozen cases are reported annually -- an estimated 11 million people worldwide are infected. Current treatments are effective only if the disease is diagnosed early.

"It takes less than two weeks for the larvae to travel from the intestine to muscle, where they live," says lead author Makedonka Mitreva, PhD, research assistant professor of genetics at Washington University's Genome Center. "Once the worms invade the muscle, drugs are less effective. While the disease is rarely deadly, patients often live for months or years with chronic muscle pain and fatigue until the worms eventually die."

Today, trichinosis occurs most often in areas of Asia and Eastern Europe where pigs are sometimes fed raw meat, and meat inspections are lax.

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The draft genome of the parasitic nematode Trichinella spiralis

Makedonka Mitreva, Douglas P Jasmer, Dante S Zarlenga, Zhengyuan Wang, Sahar Abubucker, John Martin, Christina M Taylor, Yong Yin, Lucinda Fulton, Pat Minx, Shiaw-Pyng Yang, Wesley C Warren, Robert S Fulton, Veena Bhonagiri, Xu Zhang, Kym Hallsworth-Pepin, Sandra W Clifton, James P McCarter, Judith Appleton, Elaine R Mardis & Richard K Wilson


Corresponding authors

Nature Genetics (2011) doi:10.1038/ng.769Received 16 April 2010 Accepted 21 January 2011 Published online 20 February 2011

Genome evolution studies for the phylum Nematoda have been limited by focusing on comparisons involving Caenorhabditis elegans. We report a draft genome sequence of Trichinella spiralis, a food-borne zoonotic parasite, which is the most common cause of human trichinellosis. This parasitic nematode is an extant member of a clade that diverged early in the evolution of the phylum, enabling identification of archetypical genes and molecular signatures exclusive to nematodes. We sequenced the 64-Mb nuclear genome, which is estimated to contain 15,808 protein-coding genes, at ~35-fold coverage using whole-genome shotgun and hierarchal map–assisted sequencing. Comparative genome analyses support intrachromosomal rearrangements across the phylum, disproportionate numbers of protein family deaths over births in parasitic compared to a non-parasitic nematode and a preponderance of gene-loss and -gain events in nematodes relative to Drosophila melanogaster. This genome sequence and the identified pan-phylum characteristics will contribute to genome evolution studies of Nematoda as well as strategies to combat global parasites of humans, food animals and crops.