title: Genetic diversity and molecular phylogeny of Anaplasma marginale studied longitudinally under natural transmission conditions in Rio de Janeiro, Brazil.
abstract: Anaplasma marginale is the most prevalent tick-borne pathogen in cattle in tropical and subtropical regions of the world. Major Surface Protein 1a (MSP1a) has been found to be a stable genetic marker for identifying A. marginale isolates within geographical regions. It is conserved in cattle during infection and tick-borne transmission of the pathogen. The aim of the present longitudinal study was to determine occurrences of genetic diversity associated with high prevalence of A. marginale under natural transmission conditions. Twenty calves were evaluated every 3 months during the first year of life. Rickettsemia levels due to A. marginale, measured as the number of msp1αcopies/ml in the blood of positive calves, ranged from 2.06×10(3) to 4.36×10(12). The numbers of MSP1a tandem repeats among MSP1a tandem repeats were 3 and 6. The predominant msp1α microsatellite was E, and another MSP1a tandem repeat was found that presented genotype G. Nineteen different MSP1a tandem repeats of A. marginale were found circulating in animals. The MSP1a tandem repeats 4-63-27 (27.5%), 78-24(2)-25-31 (n=21.6%) and τ-10(2)-15 (n=17.6%) were the ones most commonly observed. Twenty-two MSP1a tandem repeats resulted in new sequences with amino acid changes, as shown in this study. Thirty sequences were found for the first time in Brazil. Glycine, glutamate, serine and alanine amino acids were found at position 20. During the study, 80% (16/20) of the animals were infected by more than one genotype. Three animals were born infected, with MSP1a tandem repeats 4-63-27, 78-24(2)-25-31 and τ-10(2)-15, thus indicating occurrence of transplacental transmission. In the phylogenetic analysis, 19 different MSP1a tandem repeats of A. marginale were found in the cattle, which suggested that many MSP1a tandem repeats and high variation in MSP1a were occurring.
authors.affiliation: Departamento de Patologia Veterinária, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brazil.
authors.forename: Jenevaldo Barbosa
authors.initials: JB
authors.lastname: Silva
authors.affiliation: Departamento de Patologia Veterinária, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brazil.
authors.forename: Luiz Ricardo
authors.initials: LR
authors.lastname: Gonçalves
authors.affiliation: Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brazil.
authors.forename: Alessandro de Mello
authors.initials: Ade M
authors.lastname: Varani
authors.affiliation: Departamento de Patologia Veterinária, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brazil.
authors.forename: Marcos Rogério
authors.initials: MR
authors.lastname: André
authors.affiliation: Departamento de Patologia Veterinária, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brazil. Electronic address: zacarias@fcav.unesp.br.
authors.forename: Rosangela Zacarias
authors.initials: RZ
authors.lastname: Machado
mesh_terms: D000595:Amino Acid Sequence; D042322:Anaplasma marginale / Q000737:chemistry / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D000712:Anaplasmosis / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D001938:Brazil / Q000453:epidemiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D008137:Longitudinal Studies; D008297:Male; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins
keywords: Brazil; Cattle; Genotype; MSP1a; Tandem repeats