Cargando…
Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum
BACKGROUND: African trypanosomes (including Trypanosoma brucei) are unicellular parasites which multiply in the mammalian bloodstream. T. brucei has about twenty telomeric bloodstream form Variant Surface Glycoprotein (VSG) expression sites (BESs), of which one is expressed at a time in a mutually e...
Autores principales: | , , , , , |
---|---|
Formato: | Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2008
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2533676/ https://www.ncbi.nlm.nih.gov/pubmed/18700033 http://dx.doi.org/10.1186/1471-2164-9-385 |
_version_ | 1782159055612018688 |
---|---|
author | Young, Rosanna Taylor, Jesse E Kurioka, Ayako Becker, Marion Louis, Edward J Rudenko, Gloria |
author_facet | Young, Rosanna Taylor, Jesse E Kurioka, Ayako Becker, Marion Louis, Edward J Rudenko, Gloria |
author_sort | Young, Rosanna |
collection | PubMed |
description | BACKGROUND: African trypanosomes (including Trypanosoma brucei) are unicellular parasites which multiply in the mammalian bloodstream. T. brucei has about twenty telomeric bloodstream form Variant Surface Glycoprotein (VSG) expression sites (BESs), of which one is expressed at a time in a mutually exclusive fashion. BESs are polycistronic transcription units, containing a variety of families of expression site associated genes (ESAGs) in addition to the telomeric VSG. These polymorphic ESAG families are thought to play a role in parasite-host adaptation, and it has been proposed that ESAG diversity might be related to host range. Analysis of the genetic diversity of these telomeric gene families has been confounded by the underrepresentation of telomeric sequences in standard libraries. We have previously developed a method to selectively isolate sets of trypanosome BES containing telomeres using Transformation associated recombination (TAR) cloning in yeast. RESULTS: Here we describe the isolation of repertoires of BES containing telomeres from three trypanosome subspecies: Trypanosoma brucei gambiense DAL 972 (causative agent of West-African trypanosomiasis), T. b. brucei EATRO 2340 (a nonhuman infective strain) and T. equiperdum STIB 818 (which causes a sexually transmitted disease in equines). We have sequenced and analysed the genetic diversity at four BES loci (BES promoter region, ESAG6, ESAG5 and ESAG2) from these three trypanosome BES repertoires. CONCLUSION: With the exception of ESAG2, the BES sequence repertoires derived from T. b. gambiense are both less diverse than and nearly reciprocally monophyletic relative to those from T. b. brucei and T. equiperdum. Furthermore, although we find evidence for adaptive evolution in all three ESAG repertoires in T. b. brucei and T. equiperdum, only ESAG2 appears to be under diversifying selection in T. b. gambiense. This low level of variation in the T. b. gambiense BES sequence repertoires is consistent both with the relatively narrow host range of this subspecies and its apparent long-term clonality. However, our data does not show a clear correlation between size of trypanosome host range and either number of BESs or extent of ESAG genetic diversity. |
format | Text |
id | pubmed-2533676 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2008 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-25336762008-09-12 Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum Young, Rosanna Taylor, Jesse E Kurioka, Ayako Becker, Marion Louis, Edward J Rudenko, Gloria BMC Genomics Research Article BACKGROUND: African trypanosomes (including Trypanosoma brucei) are unicellular parasites which multiply in the mammalian bloodstream. T. brucei has about twenty telomeric bloodstream form Variant Surface Glycoprotein (VSG) expression sites (BESs), of which one is expressed at a time in a mutually exclusive fashion. BESs are polycistronic transcription units, containing a variety of families of expression site associated genes (ESAGs) in addition to the telomeric VSG. These polymorphic ESAG families are thought to play a role in parasite-host adaptation, and it has been proposed that ESAG diversity might be related to host range. Analysis of the genetic diversity of these telomeric gene families has been confounded by the underrepresentation of telomeric sequences in standard libraries. We have previously developed a method to selectively isolate sets of trypanosome BES containing telomeres using Transformation associated recombination (TAR) cloning in yeast. RESULTS: Here we describe the isolation of repertoires of BES containing telomeres from three trypanosome subspecies: Trypanosoma brucei gambiense DAL 972 (causative agent of West-African trypanosomiasis), T. b. brucei EATRO 2340 (a nonhuman infective strain) and T. equiperdum STIB 818 (which causes a sexually transmitted disease in equines). We have sequenced and analysed the genetic diversity at four BES loci (BES promoter region, ESAG6, ESAG5 and ESAG2) from these three trypanosome BES repertoires. CONCLUSION: With the exception of ESAG2, the BES sequence repertoires derived from T. b. gambiense are both less diverse than and nearly reciprocally monophyletic relative to those from T. b. brucei and T. equiperdum. Furthermore, although we find evidence for adaptive evolution in all three ESAG repertoires in T. b. brucei and T. equiperdum, only ESAG2 appears to be under diversifying selection in T. b. gambiense. This low level of variation in the T. b. gambiense BES sequence repertoires is consistent both with the relatively narrow host range of this subspecies and its apparent long-term clonality. However, our data does not show a clear correlation between size of trypanosome host range and either number of BESs or extent of ESAG genetic diversity. BioMed Central 2008-08-12 /pmc/articles/PMC2533676/ /pubmed/18700033 http://dx.doi.org/10.1186/1471-2164-9-385 Text en Copyright © 2008 Young et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Young, Rosanna Taylor, Jesse E Kurioka, Ayako Becker, Marion Louis, Edward J Rudenko, Gloria Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum |
title | Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum |
title_full | Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum |
title_fullStr | Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum |
title_full_unstemmed | Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum |
title_short | Isolation and analysis of the genetic diversity of repertoires of VSG expression site containing telomeres from Trypanosoma brucei gambiense, T. b. brucei and T. equiperdum |
title_sort | isolation and analysis of the genetic diversity of repertoires of vsg expression site containing telomeres from trypanosoma brucei gambiense, t. b. brucei and t. equiperdum |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2533676/ https://www.ncbi.nlm.nih.gov/pubmed/18700033 http://dx.doi.org/10.1186/1471-2164-9-385 |
work_keys_str_mv | AT youngrosanna isolationandanalysisofthegeneticdiversityofrepertoiresofvsgexpressionsitecontainingtelomeresfromtrypanosomabruceigambiensetbbruceiandtequiperdum AT taylorjessee isolationandanalysisofthegeneticdiversityofrepertoiresofvsgexpressionsitecontainingtelomeresfromtrypanosomabruceigambiensetbbruceiandtequiperdum AT kuriokaayako isolationandanalysisofthegeneticdiversityofrepertoiresofvsgexpressionsitecontainingtelomeresfromtrypanosomabruceigambiensetbbruceiandtequiperdum AT beckermarion isolationandanalysisofthegeneticdiversityofrepertoiresofvsgexpressionsitecontainingtelomeresfromtrypanosomabruceigambiensetbbruceiandtequiperdum AT louisedwardj isolationandanalysisofthegeneticdiversityofrepertoiresofvsgexpressionsitecontainingtelomeresfromtrypanosomabruceigambiensetbbruceiandtequiperdum AT rudenkogloria isolationandanalysisofthegeneticdiversityofrepertoiresofvsgexpressionsitecontainingtelomeresfromtrypanosomabruceigambiensetbbruceiandtequiperdum |