Role of Babesia microti Surface Antigen 1 and its Interaction with Erythrocytes in Babesiosis
babesiosis is a malaria-like disease highly prevalent in North East America that can be
fatal to the elderly and immune-compromised subjects. However, relatively little is
known about the molecular mechanisms of the disease. Babesia microti Surface Antigen 1
(BmSA1) is a membrane/secreted protein that has been previously identified and
characterized, but its functional role in ... read moreparasite invasion and growth as well as its
potential as a vaccine candidate remains to be determined. To test the role of BmSA1 in
parasite invasion, we re-evaluated published methods of in vitro invasion assays to find
optimal conditions for the quantification of parasitemia. Surprisingly, despite multiple
attempts and shared reagents, we could not reproduce published in vitro invasion assays.
Alternatively, we established an in vitro growth assay to quantify intraerythrocytic
development of Babesia microti, the most common causative agent of human babesiosis in
North America. Using the in vitro growth assay, we tested the effects of recombinant
BmSA1 protein, Signal Peptide Peptidase (SPP) inhibitor, Z-LL2 ketone, and HIV protease
inhibitors, Atazanavir and Lopinavir on parasite development in erythrocytes. Both
single and combination protocols were used to test the efficacy of potential inhibitors.
Remarkably, the Z-LL2 ketone potently inhibited B. microti growth in human erythrocytes,
and other test molecules also showed significant inhibitory effects under these
conditions. Furthermore, to identify the host erythrocyte receptor for BmSA1, I
performed multiple phage display screens using the human reticulocyte cDNA library and
far western blotting of RBC membrane proteins. Our screens suggest that BmSA1 can
recognize two potential receptors in human erythrocyte membranes of molecular mass
ranging within 200-245 kDa and 48-50 kDa. Together, these studies set
the stage for molecular identification of host receptor for BmSA1 as well as development
of potential therapeutics for human
Thesis (M.S.)--Tufts University, 2018.
Submitted to the Dept. of Pharmacology and Drug Development.
Advisor: Athar Chishti.
Keyword: Pharmacology.read less