Evidence for Extensive Genetic Diversity and Substructuring of theBabesia bovisMetapopulation

Abstract

SummaryBabesia bovis is a tick-transmitted haemoprotozoan and a causative agent of bovine babesiosis, a cattle disease that causes significant economic loss in tropical and subtropical regions. A panel of nineteen micro-and minisatellite markers was used to estimate population genetic parameters of eighteen parasite isolates originating from different continents, countries and geographic regions including North America (Mexico, USA), South America (Argentina, Brazil), the Middle East (Israel) and Australia. For eleven of the eighteen isolates, a unique haplotype was inferred suggesting selection of a single genotype by either in vitro cultivation or amplification in splenectomized calves. Furthermore, a high genetic diversity (H = 0.780) over all marker loci was estimated. Linkage disequilibrium was observed in the total study group but also in sample subgroups from the Americas, Brazil, and Israel and Australia. In contrast, corresponding to their more confined geographic origin, samples from Israel and Argentina were each found to be in equilibrium suggestive of random mating and frequent genetic exchange. The genetic differentiation (F ST ) of the total study group over all nineteen loci was estimated by analysis of variance (Θ) and Nei's estimation of heterozygosity (G ST' ) as 0.296 and 0.312, respectively. Thus, about 30% of the genetic diversity of the parasite population is associated with genetic differences between parasite isolates sampled from the different geographic regions. The pairwise similarity of multilocus genotypes (MLGs) was assessed and a neighbour-joining dendrogram generated. MLGs were found to cluster according to the country/continent of origin of isolates, but did not distinguish the attenuated from the pathogenic parasite state. The distant geographic origin of the isolates studied allows an initial glimpse into the large extent of genetic diversity and differentiation of the B. bovis population on a global scale.

Detection of Babesia spp. in High Altitude Cattle in Ecuador, Possible Evidence of the Adaptation of Vectors and Diseases to New Climatic Conditions

“…Thirty percent of the genetic diversity of Babesia spp. is associated with genetic differences between isolates in different geographic regions [36], but this diversity could also be associated with other factors such as the introduction of strains from different geographic locations, diversity of biological and mechanical vectors [7].…”

Vaccines against bovine babesiosis: where we are now and possible roads ahead

“…Finally, genome sequencing has also facilitated the study of genomic features associated with attenuation or virulence (see section on ‘Currently available vaccines’), the development of parasite transfection systems (see section on ‘Transfection as a tool for Babesia vaccine development’) and the development and application of molecular typification methods for strain characterization based on micro- and mini-satellites for B. bovis , and multilocus sequence typing for B. bovis and B. bigemina (Perez-Llaneza et al 2010; Simuunza et al 2011; Flores et al 2013; Guillemi et al 2013). High genetic diversity in the B. bovis populations was shown by both methods, while a micro- and mini-satellite approach could demonstrate population substructuring according to geographic location (Perez-Llaneza et al 2010; Simuunza et al 2011).…”

“…High genetic diversity in the B. bovis populations was shown by both methods, while a micro- and mini-satellite approach could demonstrate population substructuring according to geographic location (Perez-Llaneza et al 2010; Simuunza et al 2011). Recently, with a highly sensitive micro- and mini-satellite typing system it was possible to estimate the extensive diversity and substructuring of the B. bovis metapopulation on a global scale (Flores et al 2013).…”

Analysis of genetic diversity and population structure of Babesia gibsoni

“…Several genetic diversity studies of tick-transmitted hemoprotozoan parasites have currently been described, including Babesia bovis, Babesia ovis, Hepatozoon canis, Theileria annulata , and Theileria parva ( 27 – 31 ). These studies demonstrated that high genetic diversity was detected in B. bovis, B. ovis, T. annulata , and T. parva populations ( 28 – 31 ). A high gene flow was found between H .…”