Genetic diversity of Anaplasma marginale in Argentina

PAULA RUYBAL; MORETTA ROSALIA; PEREZ ANDRES; PETRIGH ROMINA; ZIMMER PATRICIA; ALCARAZ ELDA; ECHAIDE IGNACIO; TORIONI DE ECHAIDE SUSANA; KOCAN M KATHERINE; DE LA FUENTE JOSE; FARBER MARISA

VETERINARY PARASITOLOGY

ELSEVIER SCIENCE BV

Año: 2009 vol. 162 p. 176 - 180

0304-4017

Bovine anaplasmosis caused by Anaplasma marginale is a worldwide major constraint tocattle production. The A. marginale major surface protein 1 alpha (msp1Ą) gene contains avariable number of tandem repeats in the amino terminal region and has been used for thecharacterization of pathogen genetic diversity. This study reports the first characterization ofA. marginale genetic diversity in Argentina based on msp1Ą genotypes and its putativerelationship with Rhipicephalus (Boophilus) microplus infestations. Herein, we analyzedwhole blood bovine samples from anaplasmosis outbreaks in R. microplus infested (9samples) and eradicated/free (14 samples) regions. Sequence analysis revealed the existenceof 15 different msp1Ą genotypes with 31 different repeat units. Six new repeat sequenceswere discovered in this study and 13/31 (42%) repeats were unique to Argentinean strains.The analysis of msp1Ą repeat sequences according to R. microplus infestations resulted inthree repeat groups: (i) found in tick infested regions (20 repeats), (ii) found in tick freeregions (6 repeats) and (iii) randomly distributed (5 repeats). Moreover, A. marginale msp1Ągenetic diversity was higher in tick infested regions than in tick free areas. These results,together with previous evidence suggesting that A. marginale msp1Ą repeat units co-evolvedwith the tick vector, might represent an evidence of the role of tick-mediated transmission forthe generation of pathogen genetic diversity.