How does the variant surface glycoprotein VSG protect Trypanosoma brucei from the mammalian immune system?
Although VSG molecules are free to diffuse in the plane of the membrane (101, 102), this ~15-nm-thick VSG coat has a dual role: shield off buried invariant proteins from recognition by the hosts’ innate/acquired immune system and protect bloodstream parasites against complement-mediated lysis.
Does Trypanosoma brucei exhibit antigenic variation?
The protozoan parasite Trypanosoma brucei, a causative agent of human and animal trypanosomiasis, lives extracellularly within its host and evades host immunity through antigenic variation of its variant surface glycoprotein (VSG) coat.
What is the vector of Trypanosoma brucei?
brucei infect a human. T. brucei is transmitted between mammal hosts by an insect vector belonging to different species of tsetse fly (Glossina). Transmission occurs by biting during the insect’s blood meal….
| Trypanosoma brucei | |
|---|---|
| Family: | Trypanosomatidae |
| Genus: | Trypanosoma |
| Species: | T. brucei |
| Binomial name |
How many variant surface glycoprotein genes are expressed at once?
one VSG gene
Only one VSG gene is expressed at a time, as only one of the ~15 ES are active in a cell. VSG expression is ‘switched’ by homologous recombination of a silent basic copy gene from an array (directed by homology) into the active telomerically-located expression site.
How do trypanosomes avoid the immune system?
Trypanosoma brucei parasites successfully evade the host immune system by periodically switching the dense coat of variant surface glycoprotein (VSG) at the cell surface. Each parasite expresses VSGs in a monoallelic fashion that is tightly regulated.
What 2 types of vectors does Trypanosoma use?
cruzi vector. Trypanosoma cruzi is transmitted by kissing bugs (Hemiptera: Reduviidae). The most common genera responsible for transmission of the disease are Triatoma, Rhodnius, and Panstrongylus. Infection usually occurs after bugs defecate on the bite site and are rubbed into the wound by the host scratching.
What is the mode of transmission of trypanosomiasis?
It is caused by infection with protozoan parasites belonging to the genus Trypanosoma. They are transmitted to humans by tsetse fly (Glossina genus) bites which have acquired their infection from human beings or from animals harbouring human pathogenic parasites.
What does a surface glycoprotein do?
The variant surface glycoprotein (VSG) coat covering the membrane of African trypanosomes protects them from lytic factors in human plasma and allows them to escape the host immune reaction.
What is VSG in parasite?
Variant surface glycoprotein (VSG) is a ~60kDa protein which densely packs the cell surface of protozoan parasites belonging to the genus Trypanosoma. VSG allows the trypanosomatid parasites to evade the mammalian host’s immune system by extensive antigenic variation.
How innate and adaptive immunity are different?
The innate immune response is activated by chemical properties of the antigen. Adaptive immunity refers to antigen-specific immune response.
Is Trypanosoma an Ectoparasite?
Trypanosoma cruzi is a species of parasitic euglenoids. Amongst the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph….
| Trypanosoma cruzi | |
|---|---|
| Phylum: | Euglenozoa |
| Class: | Kinetoplastea |
| Order: | Trypanosomatida |
| Family: | Trypanosomatidae |
What kind of protein is variant surface glycoprotein?
Variant surface glycoprotein (VSG) is a ~60kDa protein which densely packs the cell surface of protozoan parasites belonging to the genus Trypanosoma. This genus is notable for their cell surface proteins. They were first isolated from Trypanosoma brucei in 1975 by George Cross.
How is mono-telomeric expression of variant surface glycoproteins ( VSGs )?
Two mechanisms for mono-telomeric expression of variant surface glycoproteins (VSGs) [12]. Only one of the 10-20 VSG telomeric sites expression sites is actively transcribed while the rest are silenced.
What are symptoms of variant surface glycoproteins ( VSGs )?
Parasites have crossed the blood-brain barrier and are now multiplying in the central nervous system. classic symptoms include rapid weight loss, impaired motor skills, seizures, confusion, and changes in personality, coma, and death. A disrupted circadian rhythm is the source of this disease’s name.
How does the variant surface glycoprotein ( VSG ) coat protect African trypanosomes?
The variant surface glycoprotein (VSG) coat covering the membrane of African trypanosomes protects them from lytic factors in human plasma and allows them to escape the host immune reaction.50 The VSG coat determines the antigenic phenotype of the parasite and protects invariant constituents of the outer membrane from the immune system.