Identification and Analysis of Immunodominant Antigens for ELISA-Based Detection of Theileria annulata.
Tropical or Mediterranean theileriosis, caused by the protozoan parasite Theileria annulata, remains an economically important bovine disease in North Africa, Southern Europe, India, the Middle East and Asia. The disease affects mainly exotic cattle and imposes serious constraints upon livestock production and breed improvement programmes. While microscopic and molecular methods exist which are capable of detecting T. annulata during acute infection, the identification of animals in the carrier state is more challenging. Serological tests, which detect antibodies that react against parasite-encoded antigens, should ideally have the potential to identify carrier animals with very high levels of sensitivity and specificity. However, assays developed to date have suffered from a lack of sensitivity and/or specificity and it is, therefore, necessary to identify novel parasite antigens, which can be developed for this purpose. In the present study, genes encoding predicted antigens were bioinformatically identified in the T. annulata genome. These proteins, together with a panel of previously described antigens, were assessed by western blot analysis for immunoreactivity, and this revealed that four novel candidates and five previously described antigens were recognised by immune bovine serum. Using a combination of immunoprecipitation and mass spectrophotometric analysis, an immunodominant protein (encoded by TA15705) was identified as Ta9, a previously defined T cell antigen. Western blotting revealed another of the five proteins in the Ta9 family, TA15710, also to be an immunodominant protein. However, validation by Enzyme-Linked Immunosorbent Assay indicated that due to either allelic polymorphism or differential immune responses of individual hosts, none of the novel candidates can be considered ideal for routine detection of T. annulata-infected/carrier animals.
Faculty of Veterinary Medicine, Department of Parasitology, Adnan Menderes University, Isıklı Mevki, 09016, Aydın, Turkey.
Huseyin Bilgin
HB
Bilgic
Faculty of Veterinary Medicine, Department of Parasitology, Adnan Menderes University, Isıklı Mevki, 09016, Aydın, Turkey.
Tulin
T
Karagenc
Faculty of Veterinary Medicine, Department of Parasitology, Adnan Menderes University, Isıklı Mevki, 09016, Aydın, Turkey.
Serkan
S
Bakırcı
Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom.
Brian
B
Shiels
Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom.
Andrew
A
Tait
Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom.
Jane
J
Kinnaird
Faculty of Veterinary Medicine, Department of Parasitology, Adnan Menderes University, Isıklı Mevki, 09016, Aydın, Turkey.
Hasan
H
Eren
Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, United Kingdom.
William
W
Weir
D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics* / Q000276:immunology; D002417:Cattle; D018503:Genome, Protozoan; D016056:Immunodominant Epitopes / Q000235:genetics* / Q000276:immunology; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000662:veterinary; D016796:Theileria annulata / Q000235:genetics / Q000276:immunology*; D013801:Theileriasis / Q000175:diagnosis* / Q000276:immunology
D000953:Antigens, Protozoan; D016056:Immunodominant Epitopes