title: Genetic variations in merozoite surface antigen genes of Babesia bovis detected in Vietnamese cattle and water buffaloes.
abstract: The genes that encode merozoite surface antigens (MSAs) in Babesia bovis are genetically diverse. In this study, we analyzed the genetic diversity of B. bovis MSA-1, MSA-2b, and MSA-2c genes in Vietnamese cattle and water buffaloes. Blood DNA samples from 258 cattle and 49 water buffaloes reared in the Thua Thien Hue province of Vietnam were screened with a B. bovis-specific diagnostic PCR assay. The B. bovis-positive DNA samples (23 cattle and 16 water buffaloes) were then subjected to PCR assays to amplify the MSA-1, MSA-2b, and MSA-2c genes. Sequencing analyses showed that the Vietnamese MSA-1 and MSA-2b sequences are genetically diverse, whereas MSA-2c is relatively conserved. The nucleotide identity values for these MSA gene sequences were similar in the cattle and water buffaloes. Consistent with the sequencing data, the Vietnamese MSA-1 and MSA-2b sequences were dispersed across several clades in the corresponding phylogenetic trees, whereas the MSA-2c sequences occurred in a single clade. Cattle- and water-buffalo-derived sequences also often clustered together on the phylogenetic trees. The Vietnamese MSA-1, MSA-2b, and MSA-2c sequences were then screened for recombination with automated methods. Of the seven recombination events detected, five and two were associated with the MSA-2b and MSA-2c recombinant sequences, respectively, whereas no MSA-1 recombinants were detected among the sequences analyzed. Recombination between the sequences derived from cattle and water buffaloes was very common, and the resultant recombinant sequences were found in both host animals. These data indicate that the genetic diversity of the MSA sequences does not differ between cattle and water buffaloes in Vietnam. They also suggest that recombination between the B. bovis MSA sequences in both cattle and water buffaloes might contribute to the genetic variation in these genes in Vietnam.
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan. Electronic address: yokoyama@obihiro.ac.jp.
authors.forename: Naoaki
authors.initials: N
authors.lastname: Yokoyama
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Thillaiampalam
authors.initials: T
authors.lastname: Sivakumar
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Bumduuren
authors.initials: B
authors.lastname: Tuvshintulga
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Hayashida
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Igarashi
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Inoue
authors.affiliation: Hue University of Agriculture and Forestry, Hue, Vietnam.
authors.forename: Phung Thang
authors.initials: PT
authors.lastname: Long
authors.affiliation: Institute of Biotechnology, Hue University, Hue, Vietnam.
authors.forename: Dinh Thi Bich
authors.initials: DTB
authors.lastname: Lan
mesh_terms: D000818:Animals; D016793:Babesia bovis / Q000235:genetics; D001404:Babesiosis / Q000453:epidemiology / Q000469:parasitology*; D002020:Buffaloes / Q000469:parasitology*; D002417:Cattle / Q000469:parasitology*; D014644:Genetic Variation; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics*; D014744:Vietnam / Q000453:epidemiology
chemical_list: D015800:Protozoan Proteins
keywords: Babesia bovis; Cattle; Genetic diversity; Merozoite surface antigen genes; Vietnam; Water buffalo