''Trypanosoma'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of kinetoplastids (class Trypanosomatidae), a monophyletic group of unicellular

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

flagellate protozoa. Trypanosoma is part of the phylum Sarcomastigophora. The name is derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''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 *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

. The majority of species are transmitted by blood-feeding

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordat ...

, but there are different mechanisms among the varying species. Some, such as '' Trypanosoma equiperdum'', are spread by direct contact. In an invertebrate host they are generally found in the intestine, but normally occupy the

bloodstream The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

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, also known as African sleeping sickness or simply sleeping sickness, is an insect-borne parasitic infection of humans and other animals. It is caused by the species ''Trypanosoma brucei''. Humans are infected by two typ ...

, caused by ''

Trypanosoma brucei ''Trypanosoma brucei'' is a species of parasitic 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 exclusively extrace ...

'', and Chagas disease, 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 o ...

.'' 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 large 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. Kinet ...

, 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 residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s for organisation during

cell division Cell division is the process by which a parent 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 eukaryotes, there ar ...

History

In 1841, Gabriel Valentin found flagellates that today are included in '' Trypanoplasma'' in the blood of

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...

. 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, Glos ...

vector of African trypanosomiasis.

Taxonomy

The monophyly of the genus ''Trypanosoma'' is not supported by a number of different methods. Rather, 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 into a branch containing all Salivarian trypanosomes and a branch containing all non-Salivarian lineages. The latter branch splits into a clade containing bird, reptilian and 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 Sarcomastigophora. The name is derived from the Greek ''trypano-'' ( ...

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

Antigenic variation Antigenic variation or antigenic alteration refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host immune response, making it one of ...

is a characteristic shared by the Salivaria, which has been particularly well-studied in '' T. brucei''. The ''

'' subgenus contains the species ''

'', '' T. rhodesiense'' and '' T. equiperdum''. The sub genus '' 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 sub genus '' Herpetosoma'' contains the species '' T. lewisi''. The sub genus '' Schizotrypanum'' contains '' T. cruzi'' and a number of bat trypanosomes. The bat species include '' Trypanosoma cruzi marinkellei'', '' Trypanosoma dionisii'', '' Trypanosoma erneyi'', '' Trypanosoma livingstonei'' and ''

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

''. Other related species include '' Trypanosoma conorhini'' and '' Trypanosoma rangeli''.

Evolution

The ancestor of modern trypanosomes absorbed a

green alga The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

around one billion years ago and co-opted some of its genetic material. This has resulted in modern trypanosomes sich 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 amphibians * '' 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 sharks (superorder Selachii), rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having five to seven pairs of g ...

* '' T. brucei'', which causes

in humans and

nagana Animal trypanosomiasis, also known as nagana and nagana pest, or sleeping sickness, is a disease of vertebrates. The disease is caused by trypanosomes of several species in the genus ''Trypanosoma'' such as ''Trypanosoma brucei''. '' Trypanosom ...

in cattle * '' T. cruzi'', which causes Chagas disease in humans * '' Trypanosoma culicavium'', 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 relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

horses, transmitted via

Tabanidae Horse-flies or horseflies are true flies in the family Tabanidae in the insect order Diptera. They are often large and agile in flight, and only the female horseflies bite animals, including humans, to obtain blood. They prefer to fly in s ...

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

dourine 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 '' Trypanosom ...

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 ''Trypanosoma ...

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 million yea ...

s and other

Equidae Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', ...

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

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

koala The koala or, inaccurately, koala bear (''Phascolarctos cinereus''), is an arboreal herbivorous marsupial native to Australia. It is the only extant representative of the family Phascolarctidae and its closest living relatives are the w ...

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

'' * '' 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 surra * '' 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 (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tele ...

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 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, Glos ...

, 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 excavates 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 trypanosomatid species ...

s. The life cycle often consists of the trypomastigote form in the vertebrate host and the trypomastigote or promastigote form in the gut of the invertebrate host. Intracellular lifecycle stages are normally found in the amastigote form. The trypomastigote morphology is unique to species in the genus ''Trypanosoma''.

Meiosis

Evidence has been obtained for meiosis in '' T. cruzi'', and for genetic exchange. '' T. brucei'' is able to undergo

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately r ...

within the

salivary gland The salivary glands in 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 minor salivary glands. Salivary ...

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. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA d ...

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