Usefulness of Babesia bigemina gp45 Gene as a Genetic Marker

THOMPSON, C.; BARAVALLE, M.E.; TORIONI DE ECHAIDE, S; SHKAP, V.; MANGOLD A.; FARBER, M.; ECHAIDE, I

Merida, Mexico

Congreso; 9th Biennial Conference of the Society of Tropical Veterinary Medicine; 2007

Society of Tropical Veterinary Medicine

Babesia bigemina, one of the Apicomplexa hemoparasites that causes bovine babesiosis, is enzootic in areas infested with Rhipicephalus spp ticks, its natural vector. Molecular markers have been used for genetic characterization of different protozoan. The gp45 gene codifying a glycoprotein expressed in the surface of the B. bigemina merozoites was previously studied by Fisher et al. (2001, Infect. Immun. 69: 3782-3790) who demonstrated genetic and transcriptional polymorphism among five Latin American strains evaluated. The aim of this work was to analyze the sequences of the gp45 gene to characterize B. bigemina (Bbi) strains from different regions with distinctive phenotypes and multiplied in vivo or in vitro. Primers previously designed to amplify a sequence of 1098 nucleotides (nt) of gp45 were used to study this gene in pathogenic (P) and attenuated strains (A) from Argentina and Israel. The gp45 sequences of BbiS1A, BbiS2P, BbiS4 (wild type) and BbiM1A, BbiM2P strains from the NW and the NE of Argentina respectively, and the gp45 sequences of BiIsA, BbiIs from Israel were compared to the reference sequence from the Mexican JG29 strain  (Genbank accession no. AF298630). The BbiS1A, BbiS2P, BbiIsA are routinely multiplied in vitro; while BbiM1A, BbiS4, BbiM2P and BbiIs are stored as frozen stabilates. The gp45 sequence was amplified from six of the seven strains evaluated, and it was unable to be amplified from BbiS2P. The alignment of the obtained sequences revealed that BbiS1A and BbiM1A, despite having a different geographic origin, showed 100% of identity between them and 75% respect to JG-29 with eight nt missing and one insertion of six nt. BbiS4 and BbiM2P had 98% similarity, while the strains from Israel showed a 100% identity between them. When pathogenic and wild Argentinean strains and the Israelis strains where compared with the JG-29 they showed a 98% and a 99% of identity respectively. New primers based on the sequence of BbiS1A allowed amplifying one fragment of 800 nt from the BbiS2P strain. The neighbor-joining analysis allowed grouping the Argentinean attenuated strains in one cluster and the three Argentinean pathogenic and wild strains plus both Israelis strains in a second cluster. There is no evidence that these differences can be attributed either to different origins or multiplication system.