Scientists discovered mechanisms that protect tapeworms from being digested by their host

October 22, 2019

A team of scientists from Tyumen together with colleagues found and described previously unknown tapeworm proteins that suppress the activity of trypsin and efficiently protect the parasites from being digested inside a host's intestinal tract. The analogs of these proteins are found in many other living organisms and were described in some other parasite worms. The results of the study were published in the Molecular & Biochemical Parasitology journal.

Tapeworms or cestodes are a class of flat parasite worms that usually have several hosts during their life cycle. The adults live in the intestinal tracts of the vertebrates and may pose a considerable threat to human and animal health. Due to their parasitic mode of life these worms completely lost their digestive apparatus but have a well-developed reproductive system and special organs that help them attach to the host's tissues. They also needed a mechanism to protect themselves from intestinal substances, specifically from digestive enzymes. One of such enzymes called trypsin breaks down proteins.

"There are lots of studies describing the inhibitors (proteins that block the activity of digestive ferments) of nematode worms and covering numerous species of these parasites, including the well-known ascarides. However, few works address the biochemistry of cestodes, and their molecular diversity is only superficially studied. The researchers of tapeworms traditionally paid attention mainly to tenias and echinococci, as they are the most dangerous for humans and animals. Other species remained understudied, and neither their inhibitors nor the mechanisms of their work have been known until recently", said Eugene Rogozhin, PhD (Bioorganic Chemistry), and a senior researcher at Tyumen State University.

The team studied the Triaenophorus nodulosus worms. These parasites are the cause of triaenophorosis -- a dangerous disease leading to mass extinction of young fish in certain freshwater species. The worms were produced from the intestines of a common pike caught in the Rybinsk Reservoir. The proteins obtained from the homogenate of the cestodes were divided into fractions using the liquid chromatography methods. After that the fractions that were the most effective in inhibiting digestive enzymes were selected. The molecular mass of the inhibitors was determined using polyacrylamide gel electrophoresis (a method based on the differences in the mobility of molecules with different sizes in a gel under the influence of an electric field). The scientists managed to identify two previously unknown polypeptides (around 14.4 kDa in mass) with different N-terminal amino-acid residues. After searching for homologous sequences the team concluded that the peptides belonged to their own type of trypsin inhibitors similar to Kunitz-type proteins that are found both in in- and vertebrates. Besides their inhibition activity, these ferments also play a role in blood clotting and inflammation processes. Proteins of the same type had been previously obtained from other tapeworm species, in which they also weakened the host's immune resistance.
-end-
The members of the team also represented Papanin Institute for the Biology of Inland Waters of the Russian Academy of Sciences, Institute of Bioorganic Chemistry of the Russian Academy of Science, Gause Institute of New Antibiotics, Institute of Systematics and Ecology of Animals of the Siberian Brunch of the Russian Academy of Sciences, and Tomsk State University.

University of Tyumen

Related Parasites Articles from Brightsurf:

When malaria parasites trick liver cells to let themselves in
A new study led by Maria Manuel Mota, group leader at Instituto de Medicina Molecular, now shows that malaria parasites secrete the protein EXP2 that is required for their entry into hepatocytes.

How deadly parasites 'glide' into human cells
A group of scientists led by EMBL Hamburg's Christian Löw provide insights into the molecular structure of proteins involved in the gliding movements through which the parasites causing malaria and toxoplasmosis invade human cells.

How malaria parasites withstand a fever's heat
The parasites that cause 200 million cases of malaria each year can withstand feverish temperatures that make their human hosts miserable.

New studies show how to save parasites and why it's important
An international group of scientists published a paper, Aug. 1, 2020, in a special edition of the journal Biological Conservation that lays out an ambitious global conservation plan for parasites.

More flowers and pollinator diversity could help protect bees from parasites
Having more flowers and maintaining diverse bee communities could help reduce the spread of bee parasites, according to a new study.

How Toxoplasma parasites glide so swiftly (video)
If you're a cat owner, you might have heard of Toxoplasma gondii, a protozoan that sometimes infects humans through contact with contaminated feces in litterboxes.

Parasites and the microbiome
In a study of ethnically diverse people from Cameroon, the presence of a parasite infection was closely linked to the make-up of the gastrointestinal microbiome, according to a research team led by Penn scientists.

Clocking in with malaria parasites
Discovery of a malaria parasite's internal clock could lead to new treatment strategies.

Feeding bluebirds helps fend off parasites
If you feed the birds in your backyard, you may be doing more than just making sure they have a source of food: you may be helping baby birds give parasites the boot.

Scientists discover how malaria parasites import sugar
Researchers at Stockholm University has established how sugar is taken up by the malaria parasite, a discovery with the potential to improve the development of antimalarial drugs.

Read More: Parasites News and Parasites Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.