Babesia microti is a tickborne hemoprotozoan parasite that causes the disease
babesiosis in humans. Babesia microti Apical Membrane Antigen-1 (AMA-1) is a
micronemal protein suspected to play a role in erythrocyte invasion. To investigate
interaction between AMA-1 and the host cell, the ectodomain region of the B. microti
ama-1 gene was cloned into an expression vector, expressed as a histidine-tagged fusion
protein, and used to probe red blood cell membrane proteins in far Western blot assays.
The B. microti ama-1 ectodomain, which excludes the signal peptide and the
transmembrane region of the open reading frame, was amplified from a cloned gene
sequence. The AMA-1 ectodomain is a membrane bound polypeptide that extends into
the extracellular space and is most likely to interact or initiate interaction with the host
red blood cell surface receptor(s). The amplicon was ligated into a protein expression
vector to produce a 58.1 kDa recombinant His-tagged fusion protein, which was
confirmed by Western blot analysis. The recombinant B. microti AMA-1 fusion protein was enriched on nickel
affinity columns and then used to probe mouse, human and horse red blood cell
membrane proteins in far Western blot assays. Babesia microti AMA-1 consistently
reacted strongly with a protein migrating at 49 kDa. A similar reaction occurred between
the B. microti AMA-1 and horse red blood cell membrane proteins, suggesting that
similar interacting proteins of this size are shared by red blood cells from the three
species.
The B. microti AMA-1 may bind to red blood cell membrane sialic-acid groups,
as shown for other Babesia spp. This may explain the signal at the 49 kDa position
observed between B. microti AMA-1 and red blood cell membrane proteins from three
different species. Further studies may determine if the binding epitopes of the red blood
cell binding partner at this position vary and contribute to the specificity of each parasite
AMA-1 for their respective host cells.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2008-08-68 |
| Date | 16 January 2010 |
| Creators | Baradji, Issa |
| Contributors | Holman, Patricia J. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation |
| Format | application/pdf |
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