Characterization of a novel Babesia bigemina gene and its potential use as molecular marker for strain discrimination

MOSQUEDA J; VICHIDO R; RAMOS J; FALCON A; AGNONE, A; TORINA A,; PETRIGH R; FARBER M; ARAUJO F; ICA A; CAMACHO-NUEZ M; FIGUEROA A; ALVAREZ A; CAMACHO E

Buenos Aires, Argentina

Conferencia; VI International Conference on Ticks and Tick-borne Pathogens; 2008

Babesia bigemina is endemic in most of the tropical and subtropical regions of the world, where it causes babesiosis to cattle. Currently, there is a lack of molecular methodologies to discriminate between strains, mainly due to a shortage of reliable molecular markers. The objective of this work was to characterize a gen that codes for a homologue to the B. bovis spherical body protein-1 and evaluate its use as molecular marker for strain discrimination. A BLAST search was done to identify a sbp-1 homologue in the genome of Babesia bigemina (www.sanger.ac.uk /Projects/B_bigemina/). A sequence was found in the genome of B. bigemina having a 57% identity to that of B. bovis sbp-1. The complete orf was amplified in DNA from a Mexican strain of B. bigemina by PCR. The amplicon containing the orf was cloned and sequenced. The sequenced gen showed a size of 1398 bp in length. Transcripts of sbp-1 were found in merozoite cDNA, suggesting the gene is transcribed. DNA from 9 additional strains from different states in Mexico and 4 different countries (Italy, Argentina, Brazil and Turkey) were also sequenced and analyzed. The gene showed size variation ranging from 1035 (Mexican vaccine strain) to 1734 bp (Turkey). The alignment analysis showed a central variable region flanked by conserved ends. The central, variable region consisted of repeats arranged in tandem as determined by informatics. The number and sequence of the repeats varied among the strains, especially those geographically distant. The gene also showed the presence of an EcoRI and an NcoI site which each cut the gen in two fragments of different size in each strain from each country.  A homologue for the Babesia bovis sbp-1 was identified for the first time in B. bigemina. This gene proved to be different in size and sequence among strains from different parts of the world and it is proposed as a candidate for strain discrimination in Babesia bigemina [Financed by INCO: 003691 and CONACYT: 52052].