Immunodominant proteins α-1 giardin and β-giardin are expressed in both assemblages A and B of Giardia lamblia

Abstract

BackgroundTo date, eight assemblages of Giardia lamblia have been described, but only assemblages A and B are known to infect humans. Despite the fact that the genomic, biological, and clinical differences found between these two assemblages has raised the possibility that they may be considered different species, there is relatively limited information on their phenotypic differences. In the present study, we developed monoclonal antibodies against alpha-1 and beta giardin, two immunodominant proteins produced during G. lamblia infection, and studied their expression and localization in WB (assemblage A) and GS trophozoites (assemblage B).ResultsThe polyclonal antibodies generated against WB trophozoites, particularly those recognizing intracellular proteins as well as the proteins present at the plasma membrane (variable-specific surface proteins), showed cross-reactivity with intracellular proteins in GS trophozoites. The use of monoclonal antibodies against beta giardin indicated ventral disc localization, particularly at the periphery in WB trophozoites. Interestingly, although beta giardin was also restricted to the ventral disc in GS trophozoites, the pattern of localization clearly differed in this assemblage. On the other hand, monoclonal antibodies against alpha-1 giardin showed plasma membrane localization in both assemblages with the bare area of GS trophozoites also being distinguished. Moreover, the same localization at the plasma membrane was observed in Portland-1 (Assemblage A) and in P15 (Assemblage E) trophozoites.ConclusionsWe found differences in localization of the beta giardin protein between assemblages A and B, but the same pattern of localization of alpha-1 giardin in strains from Assemblages A, B and E. These findings reinforce the need for more studies based on phenotypic characteristics in order to disclose how far one assemblage is from the other.

Identification of Conserved Candidate Vaccine Antigens in the Surface Proteome of Giardia lamblia

“…As a control, fixed cells were permeabilized with Triton X-100 to permit antibody access to all proteins regardless of location. For staining, we used previously validated antibodies (47,48) or generated new mouse polyclonal antibodies against the recombinant proteins. Immunoblotting of total G. lamblia lysates and staining with the new antibodies revealed the expected single bands, confirming their specificity (Fig.…”

Endoplasmic reticulum is the sorting core facility in the Golgi‐lacking protozoan Giardia lamblia

“…IFA of fixed cells was performed basically as described . Briefly, trophozoites or encysting cells were cultured in growth medium or encysting medium, respectively, harvested and allowed to attach to slides, pretreated with poly‐L‐lysine (Sigma).…”

The generation gap: Proteome changes and strain variation during encystation in Giardia duodenalis

“…The giardins are comprised of several multigene families, of which alpha-giardin has multiple representatives, and are involved in immunogenicity, the cytoskeleton, flagella motility, membrane stability, and attachment, as well as possibly assemblage-specific [40][41][42][43][44]. A total of 6 (33.33%) and 5 (27.78%) alpha-giardins were clustered in H-106 and B-2041.…”