|
B. bovis and B. bigemina 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 terriroties, 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 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. Phase 1 was end sequencing
of a Bacterial Artificial Chromosome (BAC) library. Phase 2 was whole genome
shotgun sequencing to 8X coverage. Phase 3 was gap closure. The resulting
sequence contains 9 contigs as indicated in the Table below.
| Contig |
Chromosome |
| 940 |
1 |
| 942 |
1 |
| 941 |
1 |
| 920 |
2 |
| 924 |
3 |
| 930 |
4 |
| 849 |
4 |
| 614 |
mitochondria |
| 766 |
plastid |
BLAST Babesia bovis contigs:
BLAST on local
server
Download
Sequences (Have Coordinates from BLAST
search available)
This project is a
collaboration between Washington State University, the Agricultural Research
Service - Animal Disease Research Unit (ARS-ADRU)
and The Institute for Genomic Research (www.tigr.org). Funding
is provided by
USDA/ARS CRIS 5348-32000-020-00D and SCA # 58-5348-2-683.
|
