College of Veterinary Medicine

Veterinary Microbiology and Pathology

Babesia Genome Sequencing Projects

The microscope used by
Smith and Kilbourne

Babesia bovis

B. bovis is a tick-transmitted protozoan parasite of cattle that infects and results in the destruction of erythrocytes, causing severe anemia. Smith and Kilbourne’s classic work in the late 1800’s to elucidate the cause and mechanism of transmission of the Texas Fever agent was the first definitive demonstration of a vector-borne protozoan disease.

B. bovis and B. bigeminia are important causative agents of bovine babesiosis in tropical and subtropical regions of the world, while Babesia divergens is more common in temperate climates. Babesiosis was a significant problem in the southern US till the 1940’s when it was controlled by eradication of the tick vectors by intensive acaricide dipping of cattle. However, the tick vectors are present in a buffer zone along the Rio Grande, in Mexico, and in US territories, and pose the threat of continual reemergence into the US as evidenced by occasional outbreaks of babesiosis in the border region. Emerging acaracide resistance of vector ticks in Mexico is a significant concern, since re-introduction of babesiosis into the US likely will occur via infected ticks. It is estimated that the first year cost of controlling vector ticks alone should they be introduced into the US is over $1.3 billion.  There is currently no babesial vaccine licensed for use in the US, and development of a vaccine is a high priority.

These apicomplexan parasites are related to Plasmodium spp (the causative agents of malaria) and Theilera parva (which causes theileriosis). Aside from being an agriculturally important pathogen, B. bovis resides within an important evolutionary branch within the phylogenic tree. Organisms from this branch of the tree have added substantially to our understanding of biology by the discovery of telomeres, catalytic RNA, the calvin cycle, GPI anchoring, and trans-splicing among others.

The tree of life showing the position of Babesia within the three Kingdoms.
Babesia bovis Genome Sequencing Project
Babesia bovis infected erythrocyte stained with monoclonal antibodies against MSA1 (green) and RAP1 (red). DNA is stained with DAPI (blue). Image courtesy of Juan Mosqueda.
The T2Bo Genome sequence
The Texas T2Bo strain was selected for genomic sequencing because the history of this isolate is well documented: it is known to be virulent, and it is tick transmissible. A combined clone by clone and whole genome shotgun approach was used to obtain the complete genome sequence for this organism. The resulting sequence contains 9 contigs which may be downloaded by following the links below.

Downloads (all files are zipped)
Target Gen Bank Text File

The T2Bo genome sequence papers
Brayton, K. A., A. O.T. Lau, D. R. Herndon, L. Hannick, L. S. Kappmeyer, S. J. Berens, S. L. Bidwell, W. C. Brown, J. Crabtree, D. Fadrosh, T. Feldblum, H. A. Forberger, B. J. Haas, J. M. Howell, H. Khouri, H. Koo, D. J. Mann, J. Norimine, I. T. Paulsen, D. Radune, Q. Ren, R. K. Smith Jr., C. E. Suarez, O. White, J. R. Wortman, D. P. Knowles Jr, T. F. McElwain, and V. M. Nene.  Genome sequence of Babesia bovis and comparative analysis of apicomplexan hemoprotozoa.  PLOS Pathogens.  3: 1401-1413.  2007.

E. H. Roalson, T. F. McElwain, K. A. Brayton, D. P. Knowles, and A. O. T. Lau.  Babesia bovis: a comprehensive phylogenetic analysis of plastid-encoded genes supports green algal origin of apicoplasts.  Experimental Parasitology.  123: 236-243.  2009.

Other B. bovis strains
The completed T2Bo sequence can now be used to scaffold genome assemblies of other Babesia bovis isolates that are generated with next generation sequencing technologies.  We are generating paired sequences for virulent B. bovis strains and their attenuated counterparts, generated by rapid, successive inoculation in cattle. 
BLAST Babesia contigs
BLAST on local server

Babesia equi

Babesia equi has been named Piroplasma equi (1901), Nuttallia equi (1912), and Theileria equi (1986), a classification that has not been formally adopted.  B. equi causes equine piroplasmosis, a disease that results in restricted movement of horses worldwide.  The disease occurs throughout the tropical and subtropical areas of the world, with endemic areas in many parts of Europe, Asia, Arabia, South and Central America and Africa.  B. equi is transmitted by species of ixodid ticks of the genera Dermacentor, Rhipicephalus and Hyalomma. The Florida isolate, also known as the USDA strain, was sequenced in collaboration with the J. Craig Venter Institute (JCVI) using a whole genome shotgun approach.  The resulting sequence contains 10 contigs as pictured below.  Please note the order of the internal contigs of chromosome 4 are not known.


These projects are funded by the USDA Agricultural Research Service - Animal Disease Research Unit (ARS-ADRU), USDA Formula Funds, The Wellcome Trust and the CVM Animal Health Research Center.


Please contact Audrey Lau
Last Edited: Mar 05, 2010 4:01 PM   

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