Identification of candidate transmission-blocking antigen genes in Theileria annulata and related vector-borne apicomplexan parasites

• Published in: BMC genomics Vol. 18; no. 1; p. 438
• Main Authors: Lempereur, Laetitia, Larcombe, Stephen D, Durrani, Zeeshan, Karagenc, Tulin, Bilgic, Huseyin Bilgin, Bakirci, Serkan, Hacilarlioglu, Selin, Kinnaird, Jane, Thompson, Joanne, Weir, William, Shiels, Brian
• Format: Journal Article Web Resource
• Language: English
• Published: England BioMed Central Ltd 05.06.2017; BioMed Central; BMC
• Subjects: 6-Cys domain; Amino Acid Sequence; Amino acids; Animals; Antigens; Antigens, Protozoan - chemistry; Antigens, Protozoan - genetics; Arachnids; Babesia; Babesiosis; Bioinformatic screen; Bioinformatics; Blocking; Cattle; Computational Biology; Computer Simulation; Conserved Sequence; Control; Cysteine; Disease control; Disease transmission; Disease Vectors; Domains; Economic impact; Ectoparasites; Epitopes; Epitopes, B-Lymphocyte - immunology; Gene expression; Gene sequencing; Genes; Genetic Variation; Genomics; Infection; Life cycles; Life sciences; Livestock; Malaria; Morbidity; Médecine vétérinaire & santé animale; Optimal control; Papain; Parasites; Parasitic diseases; Pathogens; Peptidase; Peptides; Plasmodium; Prevention; Proteins; Sciences du vivant; Similarity; Software; Theileria annulata; Theileria annulata - immunology; Theileria annulata - physiology; Theileriosis; Ticks; Ticks - parasitology; Ticks - physiology; Transmission-blocking vaccine; Vaccines; Vector-borne diseases; Vectors (Biology); Veterinary medicine & animal health; 6-Cys domain; Plasmodium; Bioinformatic screen; Theileria annulata; Transmission-blocking vaccine; Babesia
• ISSN: 1471-2164; 1471-2164
• DOI: 10.1186/s12864-017-3788-1

Vector-borne apicomplexan parasites are a major cause of mortality and morbidity to humans and livestock globally. The most important disease syndromes caused by these parasites are malaria, babesiosis and theileriosis. Strategies for control often target parasite stages in the mammalian host that cause disease, but this can result in reservoir infections that promote pathogen transmission and generate economic loss. Optimal control strategies should protect against clinical disease, block transmission and be applicable across related genera of parasites. We have used bioinformatics and transcriptomics to screen for transmission-blocking candidate antigens in the tick-borne apicomplexan parasite, Theileria annulata. A number of candidate antigen genes were identified which encoded amino acid domains that are conserved across vector-borne Apicomplexa (Babesia, Plasmodium and Theileria), including the Pfs48/45 6-cys domain and a novel cysteine-rich domain. Expression profiling confirmed that selected candidate genes are expressed by life cycle stages within infected ticks. Additionally, putative B cell epitopes were identified in the T. annulata gene sequences encoding the 6-cys and cysteine rich domains, in a gene encoding a putative papain-family cysteine peptidase, with similarity to the Plasmodium SERA family, and the gene encoding the T. annulata major merozoite/piroplasm surface antigen, Tams1. Candidate genes were identified that encode proteins with similarity to known transmission blocking candidates in related parasites, while one is a novel candidate conserved across vector-borne apicomplexans and has a potential role in the sexual phase of the life cycle. The results indicate that a 'One Health' approach could be utilised to develop a transmission-blocking strategy effective against vector-borne apicomplexan parasites of animals and humans.