Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity.
<h4>Background</h4>Theileria parva causes an acute fatal disease in cattle, but infections are asymptomatic in the African buffalo (Syncerus caffer). Cattle can be immunized against the parasite by infection and treatment, but immunity is partially strain specific. Available data indicat...
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Public Library of Science (PLoS)
2011-04-01
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| Online Access: | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0019015&type=printable |
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| author | Roger Pelle Simon P Graham Moses N Njahira Julius Osaso Rosemary M Saya David O Odongo Philip G Toye Paul R Spooner Anthony J Musoke Duncan M Mwangi Evans L N Taracha W Ivan Morrison William Weir Joana C Silva Richard P Bishop |
| author_facet | Roger Pelle Simon P Graham Moses N Njahira Julius Osaso Rosemary M Saya David O Odongo Philip G Toye Paul R Spooner Anthony J Musoke Duncan M Mwangi Evans L N Taracha W Ivan Morrison William Weir Joana C Silva Richard P Bishop |
| author_sort | Roger Pelle |
| collection | DOAJ |
| description | <h4>Background</h4>Theileria parva causes an acute fatal disease in cattle, but infections are asymptomatic in the African buffalo (Syncerus caffer). Cattle can be immunized against the parasite by infection and treatment, but immunity is partially strain specific. Available data indicate that CD8(+) T lymphocyte responses mediate protection and, recently, several parasite antigens recognised by CD8(+) T cells have been identified. This study set out to determine the nature and extent of polymorphism in two of these antigens, Tp1 and Tp2, which contain defined CD8(+) T-cell epitopes, and to analyse the sequences for evidence of selection.<h4>Methodology/principal findings</h4>Partial sequencing of the Tp1 gene and the full-length Tp2 gene from 82 T. parva isolates revealed extensive polymorphism in both antigens, including the epitope-containing regions. Single nucleotide polymorphisms were detected at 51 positions (∼12%) in Tp1 and in 320 positions (∼61%) in Tp2. Together with two short indels in Tp1, these resulted in 30 and 42 protein variants of Tp1 and Tp2, respectively. Although evidence of positive selection was found for multiple amino acid residues, there was no preferential involvement of T cell epitope residues. Overall, the extent of diversity was much greater in T. parva isolates originating from buffalo than in isolates known to be transmissible among cattle.<h4>Conclusions/significance</h4>The results indicate that T. parva parasites maintained in cattle represent a subset of the overall T. parva population, which has become adapted for tick transmission between cattle. The absence of obvious enrichment for positively selected amino acid residues within defined epitopes indicates either that diversity is not predominantly driven by selection exerted by host T cells, or that such selection is not detectable by the methods employed due to unidentified epitopes elsewhere in the antigens. Further functional studies are required to address this latter point. |
| format | Article |
| id | doaj-art-3ce08aaecc574375b437ae2f7867f147 |
| institution | DOAJ |
| issn | 1932-6203 |
| language | English |
| publishDate | 2011-04-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS ONE |
| spelling | doaj-art-3ce08aaecc574375b437ae2f7867f1472025-08-20T03:10:21ZengPublic Library of Science (PLoS)PLoS ONE1932-62032011-04-0164e1901510.1371/journal.pone.0019015Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity.Roger PelleSimon P GrahamMoses N NjahiraJulius OsasoRosemary M SayaDavid O OdongoPhilip G ToyePaul R SpoonerAnthony J MusokeDuncan M MwangiEvans L N TarachaW Ivan MorrisonWilliam WeirJoana C SilvaRichard P Bishop<h4>Background</h4>Theileria parva causes an acute fatal disease in cattle, but infections are asymptomatic in the African buffalo (Syncerus caffer). Cattle can be immunized against the parasite by infection and treatment, but immunity is partially strain specific. Available data indicate that CD8(+) T lymphocyte responses mediate protection and, recently, several parasite antigens recognised by CD8(+) T cells have been identified. This study set out to determine the nature and extent of polymorphism in two of these antigens, Tp1 and Tp2, which contain defined CD8(+) T-cell epitopes, and to analyse the sequences for evidence of selection.<h4>Methodology/principal findings</h4>Partial sequencing of the Tp1 gene and the full-length Tp2 gene from 82 T. parva isolates revealed extensive polymorphism in both antigens, including the epitope-containing regions. Single nucleotide polymorphisms were detected at 51 positions (∼12%) in Tp1 and in 320 positions (∼61%) in Tp2. Together with two short indels in Tp1, these resulted in 30 and 42 protein variants of Tp1 and Tp2, respectively. Although evidence of positive selection was found for multiple amino acid residues, there was no preferential involvement of T cell epitope residues. Overall, the extent of diversity was much greater in T. parva isolates originating from buffalo than in isolates known to be transmissible among cattle.<h4>Conclusions/significance</h4>The results indicate that T. parva parasites maintained in cattle represent a subset of the overall T. parva population, which has become adapted for tick transmission between cattle. The absence of obvious enrichment for positively selected amino acid residues within defined epitopes indicates either that diversity is not predominantly driven by selection exerted by host T cells, or that such selection is not detectable by the methods employed due to unidentified epitopes elsewhere in the antigens. Further functional studies are required to address this latter point.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0019015&type=printable |
| spellingShingle | Roger Pelle Simon P Graham Moses N Njahira Julius Osaso Rosemary M Saya David O Odongo Philip G Toye Paul R Spooner Anthony J Musoke Duncan M Mwangi Evans L N Taracha W Ivan Morrison William Weir Joana C Silva Richard P Bishop Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity. PLoS ONE |
| title | Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity. |
| title_full | Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity. |
| title_fullStr | Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity. |
| title_full_unstemmed | Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity. |
| title_short | Two Theileria parva CD8 T cell antigen genes are more variable in buffalo than cattle parasites, but differ in pattern of sequence diversity. |
| title_sort | two theileria parva cd8 t cell antigen genes are more variable in buffalo than cattle parasites but differ in pattern of sequence diversity |
| url | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0019015&type=printable |
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