title: Strong conservation of rhoptry-associated-protein-1 (RAP-1) locus organization and sequence among Babesia isolates infecting sheep from China (Babesia motasi-like phylogenetic group).
abstract: Rhoptry-associated-protein 1 (RAP-1) is considered as a potential vaccine candidate due to its involvement in red blood cell invasion by parasites in the genus Babesia. We examined its value as a vaccine candidate by studying RAP-1 conservation in isolates of Babesia sp. BQ1 Ningxian, Babesia sp. Tianzhu and Babesia sp. Hebei, responsible for ovine babesiosis in different regions of China. The rap-1 locus in these isolates has very similar features to those described for Babesia sp. BQ1 Lintan, another Chinese isolate also in the B. motasi-like phylogenetic group, namely the presence of three types of rap-1 genes (rap-1a, rap-1b and rap-1c), multiple conserved rap-1b copies (5) interspaced with more or less variable rap-1a copies (6), and the 3' localization of one rap-1c. The isolates Babesia sp. Tianzhu, Babesia sp. BQ1 Lintan and Ningxian were almost identical (average nucleotide identity of 99.9%) over a putative locus of about 31 Kb, including the intergenic regions. Babesia sp. Hebei showed a similar locus organization but differed in the rap-1 locus sequence, for each gene and intergenic region, with an average nucleotide identity of 78%. Our results are in agreement with 18S rDNA phylogenetic studies performed on these isolates. However, in extremely closely related isolates the rap-1 locus seems more conserved (99.9%) than the 18S rDNA (98.7%), whereas in still closely related isolates the identities are much lower (78%) compared with the 18S rDNA (97.7%). The particularities of the rap-1 locus in terms of evolution, phylogeny, diagnosis and vaccine development are discussed.
authors.affiliation: INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France.
authors.forename: Qingli
authors.initials: Q
authors.lastname: Niu
authors.affiliation: INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Valentin
authors.affiliation: INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Bonsergent
authors.affiliation: INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, CS 40706, F-44307 Nantes, France; LUNAM Université, Oniris, UMR1300 BioEpAR, F-44307 Nantes, France. Electronic address: laurence.malandrin@oniris-nantes.fr.
authors.forename: Laurence
authors.initials: L
authors.lastname: Malandrin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001403:Babesia / Q000145:classification* / Q000235:genetics*; D001404:Babesiosis / Q000469:parasitology*; D002681:China; D019295:Computational Biology; D017124:Conserved Sequence; D021901:DNA, Intergenic; D019143:Evolution, Molecular; D018628:Gene Dosage; D056426:Genetic Loci; D018503:Genome, Protozoan; D008969:Molecular Sequence Data; D010802:Phylogeny; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*
chemical_list: D021901:DNA, Intergenic; D015800:Protozoan Proteins; C097551:rhoptry-associated protein-1, Babesia
keywords: Babesia motasi-like species; Genetic diversity; Multigene family; Rhoptry-associated-protein 1