A potentially important excretory–secretory product of Giardia lamblia

Abstract

In this study we have reported the detailed characterization of a 58 kDa excretory–secretory product (ESP) of Giardia lamblia. The method of purification has been simplified which has improved the purification fold as well as the yield of the ESP. The binding efficacy of disialoganglioside (GD 2) to the purified ESP was found to be maximum among all other gangliosides used. The N-terminal sequence of the immunoreactive 29 kDa peptide obtained from partial tryptic digest of the ESP was found to be ADFVPQVST. The IgG against the purified ESP (IgG ES) showed cross-reactivity with the binding subunit of the commercially available cholera toxin and also with two protein bands of western cottonmouth moccasin snake toxin. The ESP could accumulate fluid in the intestine of sealed adult mice and also induce morphological changes in HEp-2 cells. The crude extract of G. lamblia trophozoites preincubated with Escherichia coli revealed 8-fold augmentation in the cytopathic activity on HEp-2 cells as compared to that of crude preparation from trophozoites only. Index Descriptors and Abbreviations: BSA, bovine serum albumin; OPD, O-phenylenediamine; HRP, horse radish peroxidase; FPLC, fast protein liquid chromatography; MEM, Eagle’s minimum essential medium; SDS–PAGE; sodium dodecyl sulfate polyacrylamide gel electrophoresis; kDa, kilodalton; GM 1, Galβ3GalNAcβ4(NeuAcα3)Galβ4Glcβceramide; GD 3, NeuAcα8NeuAcα3Galβ4Glcβceramide; GD 2,GalNAcβ4(NeuAcα8NeuAcα3)Galβ4Glcβceramide; GD 1a, NeuAcα3Galβ3GalNAcβ4(NeuAcα3)Galβ4Glcβceramide; GD 1b, Galβ3GalNAcβ4(NeuAcα8NeuAcα3)Galβ4Glcβceramide; GT 1b, NeuAcα3Galβ3GalNAcβ4(NeuAcα8NeuAcα3)Galβ4Glcβceramide