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Title: Characterization of giardin protein expression during encystation of Giardia duodenalis

item Jenkins, Mark
item Obrien, Celia
item Macarisin, Dumitru
item Karns, Jeffrey
item Santin-Duran, Monica
item Fayer, Ronald

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/29/2010
Publication Date: 7/31/2010
Citation: Jenkins, M.C., Obrien, C.N., Macarisin, D., Karns, J.S., Santin, M., Fayer, R. 2010. Characterization of giardin protein expression during encystation of Giardia duodenalis. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Giardia duodenalis trophozoites attach to the gut surface by means of a ventral disk that contains various giardin proteins that appear to be important to VD structural integrity. One approach to preventing giardiasis is to stimulate giardin-specific antibodies and thereby block trophozoite attachment to the gut epithelium. Understanding giardin expression during encystation (cyst formation) or excystation (trophozoite release) might provide clues to the role of giardins in the Giardia life-cycle. In the present study expression of major giardin proteins during in vitro conversion of trophozoites to cysts was characterized. Quantitative RT-PCR using giardin-specific primers provided data on the expression of each respective gene sequence relative to house-keeping genes over time. Immunoblotting using giardin-specific antisera revealed the presence of beta- and delta-giardin at all timepoints during encystation. Moreover, immunofluorescence assay showed that both giardins were localized to a well-defined ventral disk early in encystation, and then was increasingly localized to an amorphous structure inside the cysts as early as 48 hr during encystation. Dual color labeling of G. duodenalis trophozoites with antisera to delta and beta giardin followed by confocal epifluorscence microscopy revealed the spatial organization of the two major giardin proteins in the trophozoite stage. These findings confirm earlier observations that the VD is disassembled during encystation, and provide interesting insight on the unique metabolic activities of G. duodenalis during encystation.