Fig. 2.

Multiple amino acid sequence alignment of six Tp1 antigen variants in 116 T. parva samples obtained from DRC and Burundi. Antigen variants are named var-1 to var-34. The single letter amino acid code is used. The antigen variants nomenclature used in this study was first proposed by Pelle et al. [36]. Variants var-1 and var-3 were first described by Pelle et al. [36] and var-31 by Salih et al. [37]. The numbers in square brackets behind variants names indicate the number of T. parva isolates represented by each variant. The single previously identified T. parva CD8⁺ T cell target epitope is bolded and boxed. The polymorphic residues in the T cell epitope are coloured in red. Conserved amino acid residues are denoted by (*) below the alignment, and dashes (–) denote insertion region. Nested PCR primers used for sequencing are shaded and boxed in flanked regions. The Muguga sequence (GenBank: JF451936) was used as the reference sequence; it represents the other component of the Muguga cocktail vaccine (Serengeti-transformed and Kiambu 5) that are identical to Muguga strain sequence for the Tp1 locus. Tp1 antigen variant var-1 is found in the three Muguga vaccine strains. Corresponding gene alleles and sample characteristics are presented in Additional file 3: Table S3