''Trypanosoma'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

kinetoplastid Kinetoplastida (or Kinetoplastea, as a class) is a group of flagellated protists belonging to the phylum Euglenozoa, and characterised by the presence of a distinctive organelle called the kinetoplast (hence the name), a granule containing a lar ...

s (class Trypanosomatidae), a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group of unicellular

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and the ...

protozoa Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically ...

. Trypanosoma is part of the phylum

Euglenozoa Euglenozoa are a large group of flagellate Discoba. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. Euglenozoa are represented by four major groups, ''i.e.,'' Kinetoplastea, ...

. The name is derived from the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

''trypano-'' (borer) and ''soma'' (body) because of their corkscrew-like motion. Most trypanosomes are

heteroxenous Heteroxeny, or heteroxenous development, characterizes a parasite whose development involves several host species. Heteroxeny has been used as the basis for splitting genera. When there are two or three hosts, the development cycle is named d ...

(requiring more than one obligatory host to complete life cycle) and most are transmitted via a

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

. The majority of species are transmitted by blood-feeding

invertebrates Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum ...

, but there are different mechanisms among the varying species. ''

Trypanosoma equiperdum ''Τrypanosoma equiperdum'' is a species of kinetoplastid parasites that causes covering sickness in horses and other animals in the family Equidae. ''T. equiperdum'' is the only known trypanosome that is not spread by an insect vector. There ha ...

'' is spread between horses and other

equine Equinae is a subfamily of the family Equidae, known from the Hemingfordian stage of the Early Miocene (16 million years ago) onwards. They originated in North America, before dispersing to every continent except Australia and Antarctica. They are ...

species by sexual contact. They are generally found in the

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

of their invertebrate host, but normally occupy the

bloodstream In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart an ...

or an

intracellular This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions ...

environment in the vertebrate host. Trypanosomes infect a variety of hosts and cause various diseases, including the fatal human diseases

sleeping sickness African trypanosomiasis is an insect-borne parasitic infection of humans and other animals. Human African trypanosomiasis (HAT), also known as African sleeping sickness or simply sleeping sickness, is caused by the species '' Trypanosoma b ...

, caused by ''

Trypanosoma brucei ''Trypanosoma brucei'' is a species of parasitic Kinetoplastida, kinetoplastid belonging to the genus ''Trypanosoma'' that is present in sub-Saharan Africa. Unlike other protozoan parasites that normally infect blood and tissue cells, it is excl ...

'', and

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change throughout the ...

, caused by ''

Trypanosoma cruzi ''Trypanosoma cruzi'' is a species of parasitic euglenoids. Among the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood ...

.'' The mitochondrial genome of the ''Trypanosoma'', as well as of other kinetoplastids, known as the

kinetoplast A kinetoplast is a network of circular DNA (called kDNA) inside a mitochondrion that contains many copies of the mitochondrial genome. The most common kinetoplast structure is a disk, but they have been observed in other arrangements. Kinetoplasts ...

, is made up of a highly complex series of catenated circles and minicircles and requires a cohort of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s for organisation during

cell division Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...

History

In 1841,

Gabriel Valentin Gabriel Gustav Valentin (July 1810 – 24 May 1883), also Gabriel Valentin, was a German physiologist and professor of physiology at the University of Bern. Gabriel Gustav Valentin was born at Breslau in July 1810. He was Jewish, the son of a Jew ...

found flagellates that today are included in ''

Trypanoplasma ''Cryptobia'' is a genus of Kinetoplastida, kinetoplastids. Several species are known for being fish pathogens. They can be found in other animals, as well. The name ''Trypanoplasma'' is occasionally used for some of these.Woo, P. T. K. (2003)''Cr ...

'' in the blood of

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

. The genus (''T. sanguinis'') was named by Gruby in 1843, after parasites in the blood of frogs. In 1903, David Bruce identified the protozoan parasite and the

tsetse fly Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies) are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Gloss ...

vector of

African trypanosomiasis African trypanosomiasis is an insect-borne parasitic infection of humans and other animals. Human African trypanosomiasis (HAT), also known as African sleeping sickness or simply sleeping sickness, is caused by the species ''Trypanosoma bru ...

Taxonomy

A number of different methods demonstrate that the traditional ''Trypanosoma'' genus is not monophyletic, with the biflagellate

Bodonida Bodonida is an order of Kinetoplastida, kinetoplastid flagellate Excavata, excavates. It contains the genera ''Bodo (genus), Bodo'' and ''Rhynchomonas'', relatives to the parasitic Trypanosoma, trypanosomes. This order also contains the colonial ...

nested within. The American and African trypanosomes constitute distinct clades, implying that the major human disease agents ''T. cruzi'' (cause of Chagas' disease) and ''T. brucei'' (cause of African sleeping sickness) are not closely related to each other. Phylogenetic analyses suggest an ancient split between a branch containing all Salivarian trypanosomes and a branch containing all non-Salivarian lineages. The latter branch in turn splits into a clade containing bird, reptilian and the Stercorarian trypanosomes infecting mammals, and a clade with a branch of fish trypanosomes and a branch of reptilian or amphibian lineages. Salivarians are trypanosomes of the subgenera of '' Duttonella'', ''

Trypanozoon ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (bore ...

'', '' Pycnomonas'' and '' Nannomonas'', which are passed to the vertebrate recipient in the saliva of the tsetse fly (''Glossina spp.'').

Antigenic variation Antigenic variation or antigenic alteration refers to the mechanism by which an Pathogen, infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host (biology), host immune r ...

is a characteristic shared by the Salivaria, which has been particularly well-studied in ''

T. brucei T, or t, is the twentieth letter of the English alphabet. T may also refer to: Codes and units * T, Tera- as in one trillion * T, the symbol for "True" in logic * T, the usual symbol for period, the reciprocal of frequency * T, the symbol ...

''. The ''

'' subgenus contains the species ''

'', '' T. rhodesiense'' and '' T. equiperdum''. The subgenus '' Duttonella'' contains the species '' T. vivax''. '' Nannomonas'' contains '' T. congolense''.Dihydrofolate reductases within the genus Trypanosoma. J.J. Jaffe, J.J. McCormack Jr and W.E. Gutteridge, Experimental Parasitology, 1969, Volume 25, Pages 311–318, Stercorians are trypanosomes passed to the recipient in the feces of insects from the subfamily ''

Triatominae The members of the Triatominae , a subfamily of the Reduviidae, are also known as conenose bugs, kissing bugs (so-called from their habit of feeding from around the mouths of people), or vampire bugs. Other local names for them used in the Amer ...

'' (most importantly ''

Triatoma infestans ''Triatoma infestans'', commonly called winchuka or vinchuca in Argentina, Bolivia, Uruguay and Chile, barbeiro in Brazil, chipo in Venezuela and also known as "kissing bug" or "barber bug" in English, is a blood-sucking bug (like virtually a ...

''). This group includes ''

'', '' T. lewisi'', '' T. melophagium'', '' T. nabiasi'', '' T. rangeli'', '' T. theileri'', '' T. theodori''. The subgenus '' Herpetosoma'' contains the species '' T. lewisi''. The subgenus '' Schizotrypanum'' contains ''

T. cruzi ''Trypanosoma cruzi'' is a species of parasitic euglenoids. Among the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of ...

'' and a number of bat trypanosomes. The bat species include '' Trypanosoma cruzi marinkellei'', ''

Trypanosoma dionisii ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (bore ...

'', ''

Trypanosoma erneyi ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (bore ...

'', ''

Trypanosoma livingstonei ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (bore ...

'' and ''

Trypanosoma wauwau ''Trypanosoma'' is a genus of Kinetoplastida, kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasite, parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancien ...

''. Other related species include ''

Trypanosoma conorhini ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (bore ...

'' and ''

Trypanosoma rangeli ''Trypanosoma rangeli'' is a species of hemoflagellate excavate parasites of the genus Trypanosoma. Although infecting a variety of mammalian species in a wide geographical area in Central and South America, this parasite is considered non-pathog ...

''.

Evolution

The ancestor of modern trypanosomes absorbed a

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

around one billion years ago and co-opted some of its genetic material. This has resulted in modern trypanosomes such as ''T. brucei'' containing essential genes for the breakdown of sugars that are most closely related to plants. This difference may be used as the target of therapies. The relationships between the species have not been worked out to date. It has been suggested that ''T. evansi'' arose from a clone of ''T. equiperdum'' which lost its maxicircles.Brun R, Hecker H, Lun ZR (1998) ''Trypanosoma evansi'' and ''T. equiperdum'': distribution, biology, treatment and phylogenetic relationship (a review). Vet Parasitol 79(2):95-107 It has also been proposed that ''T. evansi'' should be classified as a subspecies of ''T. brucei''.Carnes J, Anupama A, Balmer O, Jackson A, Lewis M, Brown R, Cestari I, Desquesnes M, Gendrin C, Hertz-Fowler C, Imamura H, Ivens A, Kořený L, Lai DH, MacLeod A, McDermott SM, Merritt C, Monnerat S, Moon W, Myler P, Phan I, Ramasamy G, Sivam D, Lun ZR, Lukeš J, Stuart K, Schnaufer A (2015) Genome and phylogenetic analyses of ''Trypanosoma evansi'' reveal extensive similarity to ''T. brucei'' and multiple independent origins for dyskinetoplasty. PLoS Negl Trop Dis 9(1):e3404. doi: 10.1371/journal.pntd.0003404 It has been shown that ''T. equiperdum'' has emerged at least once in Eastern Africa and ''T. evansi'' at two independent occasions in Western Africa.Cuypers B, Van den Broeck F, Van Reet N, Meehan CJ, Cauchard J, Wilkes JM, Claes F, Goddeeris B, Birhanu H, Dujardin JC, Laukens K, Büscher P, Deborggraeve S (2017) Genome-wide SNP analysis reveals distinct origins of ''Trypanosoma evansi'' and ''Trypanosoma equiperdum''. Genome Biol Evol doi: 10.1093/gbe/evx102

Selected species

Species of ''Trypanosoma'' include the following: * '' T. ambystomae''. in

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

s * '' T. antiquus'', extinct (Fossil in Miocene amber) * '' T. avium'', which infects birds and blackflies * '' T. bennetti'', which infects birds and biting midges * '' T. boissoni'', in

elasmobranch Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks ( division Selachii), and batomorphs (division Batomorphi, including rays, skates, and sawfish). Members of this subclass are characterised by h ...

* ''

'', which causes

in humans and

nagana Animal trypanosomiasis, also known as nagana and nagana pest, or sleeping sickness, is a disease of non-human vertebrates. The disease is caused by trypanosomes of several species in the genus ''Trypanosoma'' such as '' T. brucei'' (which also ...

in cattle * ''

'', which causes

in humans * ''

Trypanosoma culicavium ''Trypanosoma'' is a genus of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Ancient Greek ''trypano-'' (bore ...

'', which infects birds and mosquitoes * '' T. congolense'', which causes

in ruminant livestock, horses and a wide range of wildlife * '' T. equinum'', in

South American South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

horses, transmitted via

Tabanidae Horse flies and deer flies are true flies in the family Tabanidae in the insect order Diptera. The adults are often large and agile in flight. Only females bite land vertebrates, including humans, to obtain blood. They prefer to fly in sunli ...

, * '' T. equiperdum'', which causes dourine or

covering sickness Covering sickness, or dourine (French, from the Arabic ''darina'', meaning mangy (said of a female camel), feminine of ''darin'', meaning dirty), is a disease of horses and other members of the family Equidae. The disease is caused by '' Trypanoso ...

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

s and other

Equidae Equidae (commonly known as the horse family) is the Taxonomy (biology), taxonomic Family (biology), family of Wild horse, horses and related animals, including Asinus, asses, zebra, zebras, and many extinct species known only from fossils. The fa ...

, it can be spread through coitus. * '' T. evansi'', which causes one form of the disease

surra Surra (from the Marathi language, Marathi ''sūra'', meaning the sound of heavy breathing through nostrils, of imitative origin) is a disease of vertebrate animals. The disease is caused by protozoan trypanosomes, specifically ''Trypanosoma e ...

in certain animals including camels Article Number 21. p.2 (a single case report of human infection in 2005 in India was successfully treated with

suramin Suramin is a medication used to treat African sleeping sickness and river blindness. It is the treatment of choice for sleeping sickness without central nervous system involvement. It is given by injection into a vein. Suramin causes a fai ...

) * '' T. everetti'', in birds * '' T. hosei'', in

s * '' T. irwini'', in

koala The koala (''Phascolarctos cinereus''), sometimes inaccurately called the koala bear, is an arboreal herbivorous marsupial native to Australia. It is the only Extant taxon, extant representative of the Family (biology), family ''Phascolar ...

s * '' T. lewisi'', in rats * '' T. melophagium'', in sheep, transmitted via ''

Melophagus ovinus ''Melophagus ovinus'', or the sheep ked, is a brown, hairy fly that resembles a tick. This wingless fly is about 4 to 6 mm long and has a small head; it is a fly from the family Hippoboscidae. They are blood-feeding parasites of sheep. The ...

'' * '' T. parroti'', in amphibians * '' T. percae'', in the species ''

Perca fluviatilis The European perch (''Perca fluviatilis''), also known as the common perch, redfin perch, big-scaled redfin, English perch, Euro perch, Eurasian perch, Eurasian river perch, Hatch, poor man's rockfish or in Anglophone parts of Europe, simply the ...

'' * '' T. phedinae'' * '' T. rangeli'', believed to be nonpathogenic to humans * '' T. rotatorium'', in amphibians * '' T. rugosae'', in amphibians * '' T. sergenti'', in amphibians * '' T. simiae'', which causes

in pigs. Its main reservoirs are warthogs and bush pigs * '' T. sinipercae'', in fishes * '' T. suis'', which causes a different form of

* '' T. theileri'', a large trypanosome infecting ruminants and transmitted by a variety of vectors including tabanids and mosquitoes * '' T. thomasbancrofti'', an avian trypanosome with culicine mosquito vector * '' T. triglae'', in marine

teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

s * '' T. tungarae'', in frogs * '' T. vivax'', which causes the disease

, mainly in West Africa, although it has spread to South America

Hosts, life cycle and morphologies

Two different types of trypanosomes exist, and their life cycles are different, the salivarian species and the stercorarian species. Stercorarian trypanosomes infect insects, most often the triatomid kissing bug, by developing in the posterior gut followed by release into the feces and subsequent depositing on the skin of the vertebrate host. The organism then penetrates and can disseminate throughout the body. Insects become infected when taking a blood meal. Salivarian trypanosomes develop in the anterior gut of insects, most importantly the

Tsetse fly Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies) are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Gloss ...

, and infective organisms are inoculated into the host by the insect bite before it feeds. As trypanosomes progress through their life cycle they undergo a series of morphological changes as is typical of

trypanosomatid Trypanosomatida is a group of kinetoplastid unicellular organisms distinguished by having only a single flagellum. The name is derived from the Greek ''trypano'' (borer) and ''soma'' (body) because of the corkscrew-like motion of some trypanosoma ...

s. The life cycle often consists of the

trypomastigote Trypanosomatida is a group of kinetoplastid unicellular organisms distinguished by having only a single flagellum. The name is derived from the Greek language, Greek ''trypano'' (borer) and ''soma'' (body) because of the corkscrew-like motion of ...

form in the vertebrate host and the trypomastigote or

promastigote Trypanosomatida is a group of kinetoplastid unicellular organisms distinguished by having only a single flagellum. The name is derived from the Greek ''trypano'' (borer) and ''soma'' (body) because of the corkscrew-like motion of some trypanosoma ...

form in the gut of the invertebrate host. Intracellular lifecycle stages are normally found in the

amastigote An amastigote is a protist cell that does not have visible external flagella or cilia. The term is used mainly to describe an intracellular phase in the life-cycle of trypanosomes that replicates. It is also called the leishmanial stage, since in ...

form. The trypomastigote morphology is unique to species in the genus ''Trypanosoma''.

Meiosis

Evidence has been obtained for meiosis in ''

'', and for genetic exchange. ''

'' is able to undergo

meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...

within the

salivary gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

s of its

host, and meiosis is considered to be an intrinsic part of the ''T. brucei'' developmental cycle. An adaptive benefit of meiosis for ''T. crucei'' and ''T. brucei'' may be the recombinational repair of

DNA damage DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer. DNA is constantly modified ...

s that are acquired in the hostile environment of their respective hosts.Bernstein H, Bernstein C, Michod RE (2018). Sex in microbial pathogens. ''Infection, Genetics and Evolution'' volume 57, pages 8-25. https://doi.org/10.1016/j.meegid.2017.10.024

References

External links

Trypanosoma
reviewed and published by Wikivet, accessed 08/10/2011.
Trykipedia
Trypanosomatid specific ontologies
Tree of Life: Trypanosoma
{{Authority control Trypanosomatida Fish diseases Euglenozoa genera pl:Świdrowce