What is antigenic variation in trypanosomes?

What is antigenic variation in trypanosomes?

Trypanosome persistence in the mammal is due to antigenic variation, which involves changes in the identity of the variant surface glycoprotein (VSG) that forms a dense cell surface coat to shield invariant surface antigens from immune recognition.

How does antigenic variation occur?

Antigenic variation can occur by altering a variety of surface molecules including proteins and carbohydrates. Antigenic variation can result from gene conversion, site-specific DNA inversions, hypermutation, or recombination of sequence cassettes.

What is the life cycle of T. cruzi?

The life cycle of Trypanosoma cruzi involves two intermediate hosts: the invertebrate vector (triatomine insects) and the vertebrate host (humans) and has three developmental stages namely, trypomastigotes, amastigotes and epimastigotes [8].

What is the pathogenesis of Trypanosoma cruzi?

cruzi infections is phagocytosis. Virulent metacyclic trypomastigotes replicate inside macrophages, and although many parasites are destroyed in the phagocytic vacuole, intracellular dividing amastigotes transform into trypomastigotes that escape into the blood to infect any other cell in the host’s body.

What is an example of antigenic variation?

Examples of random antigenic variation are those that occur in viruses such as the influenza virus and the human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS). The major antigenic components of these viruses are glycoproteins that make up their viral coat.

How does antigenic variation affect vaccines?

As a result, memory cells do not detect the altered antigens and are no longer effective against the pathogen. This is called antigenic variation. Influenza (flu) viruses are a good example of antigenic variation. The antigens of a flu virus can change so frequently that flu vaccines quickly become ineffective.

What is the difference between phase variation and antigenic variation?

Phase variation or phenotypic switch allows the expression of a given phenotype to be switched ON or OFF. Antigenic variation refers to the expression of a number of alternative forms of an antigen on the cell surface, and at a molecular level, shares common features with phase variation mechanisms.

How does antigenic variation by protozoan pathogens helps them survive in the host?

By concealing the parasite antigens, this strategy also delays detection by the immune system. Antigenic Variation: Some protozoan parasites change their surface antigens during the course of an infection. Parasites carrying the new antigens escape the immune response to the original antigens.

What are the life cycle of Trypanosoma Gambiense?

Trypanosoma gambiense is digenetic; i.e., it completes its life cycle in two hosts. The primary or definitive host is man. The mammals, like pigs, buffaloes, antelopes often act as reservoir hosts harbouring the parasite. The intermediate host is blood sucking insect called tsetse fly (Glossina palpalis).

How does Trypanosoma brucei accomplish antigen variation?

As a survival strategy, antigenic variation succeeds by prolonging the time that the parasite resides in the host, thereby enhancing transmission to a new host, which occurs via the tsetse fly (Glossina spp.) vector.

How is Trypanosoma cruzi transmitted to the host?

The protozoan parasite, Trypanosoma cruzi, causes Chagas disease, a zoonotic disease that can be transmitted to humans by blood-sucking triatomine bugs.

What is the life cycle of a tsetse fly?

Female tsetse mate just once. After 7 – 9 days she produces a single egg which develops into a larva within her uterus. About nine days later, the mother produces a larva which burrows into the ground where it pupates. The mother continues to produce a single larva at roughly nine day intervals for her entire life.

What is life cycle of Trypanosoma Gambiense?

Does T cruzi have antigenic variation?

cruzi adopts this type of antigenic variation. Instead, the entire T. cruzi population simultaneously exposes a variety of antigenic surface proteins, such as mucins, trans-sialidase, and MASPs, encoded by highly polymorphic multigene families (22, 80, 82, 129, 130).

Does P falciparum undergo antigenic variation?

Antigenic variation in the human malaria parasite Plasmodium falciparum involves sequential and mutually exclusive expression of members of the var multi-gene family and appears to follow a non-random pattern.

What is the vector that transmits the Trypanosoma parasite?

The tsetse fly, Glossina sp. is the main vector for trypanosomes, the parasites that cause trypanosomiasis. This disease affects both humans and livestock.