Scientists Map Genome For Parasite Causing Widespread Infections

Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: Genetics;  Biology / Biochemistry
Article Date: 30 Jun 2009 - 0:00 PDT

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Scientists at the Southwest Foundation for Biomedical Research (SFBR) in San Antonio have for the first time constructed a genetic map of the parasite that causes schistosomiasis, a chronic intestinal infection that can damage internal organs and, in children, impair growth and cognitive development. Schistosome parasites are flatworms that infect more than 200 million people a year worldwide. Infection results in an estimated 200,000 deaths annually in sub-Saharan Africa alone, while 20 million suffer severe disease, according to the World Health Organization.

"A genetic map is the essential tool needed for finding the genes that are responsible for drug resistance and pathogenesis in this parasite. In the case of drug resistance, identification of underlying mutations is critical for management of this disease" said Timothy Anderson, Ph.D., of SFBR's department of genetics.

"First, identification of mutations allows us to better understand the mechanism of action of the drugs used, and to redesign drugs to restore treatment efficacy. Second, identification of mutations involved allows us to efficiently monitor the spread of resistance in parasite populations using simple molecular methods."

The new study was published in the June 30, 2009 issue of the journal Genome Biology, and was supported by the National Institutes of Health.

Anderson, Charles Criscione, formerly of SFBR and now at Texas A&M University in College Station, and Phil LoVerde, now at the University of Texas Health Science Center in San Antonio used two adult flatworms to breed 88 S. mansoni offspring. By comparing the genetic information of the offspring to the parents, they generated a genetic map of chromosomes of the pathogen. Key contributers to the study included Claudia Valentim of SFBR and UTHSCSA and Hirohisa Hirai of Kyoto University in Japan.

These parasites have a complex lifecycle. Adult male and female worms measuring around half an inch, live in pairs in the blood vessels, and eggs are expelled in the feces or urine. The larval parasites initially develop in water snails and human infection occurs when parasite larvae burrow through the skin of people entering the water. There are an estimated 400,000 imported cases in mainland USA. These parasites are an increasing public health threat in developing countries as a consequence of large scale dam construction projects.

The researchers are planning further research using the genetic map to understand why some parasites cause more pathology than others.

Source
Southwest Foundation for Biomedical Research

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