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

FELIZIANI, C; MERINO, M C; RIVERO, M R; HELLMAN, U; PISTORESI-PALENCIA, M C; ROPOLO A S

BMC MICROBIOLOGY

BIOMED CENTRAL LTD

Año: 2011 p. 233 - 242

1471-2180

Background: To date, eight assemblages of Giardia lamblia have been described, but only assemblages A and Bare known to infect humans. Despite the fact that the genomic, biological, and clinical differences found betweenthese two assemblages has raised the possibility that they may be considered different species, there is relativelylimited information on their phenotypic differences. In the present study, we developed monoclonal antibodiesagainst alpha-1 and beta giardin, two immunodominant proteins produced during G. lamblia infection, and studiedtheir expression and localization in WB (assemblage A) and GS trophozoites (assemblage B).Results: The polyclonal antibodies generated against WB trophozoites, particularly those recognizing intracellularproteins as well as the proteins present at the plasma membrane (variable-specific surface proteins), showed crossreactivitywith intracellular proteins in GS trophozoites. The use of monoclonal antibodies against beta giardinindicated ventral disc localization, particularly at the periphery in WB trophozoites. Interestingly, although betagiardin was also restricted to the ventral disc in GS trophozoites, the pattern of localization clearly differed in thisassemblage. On the other hand, monoclonal antibodies against alpha-1 giardin showed plasma membranelocalization in both assemblages with the bare area of GS trophozoites also being distinguished. Moreover, thesame localization at the plasma membrane was observed in Portland-1 (Assemblage A) and in P15 (Assemblage E)trophozoites.Conclusions: We found differences in localization of the beta giardin protein between assemblages A and B, butthe same pattern of localization of alpha-1 giardin in strains from Assemblages A, B and E. These findings reinforcethe need for more studies based on phenotypic characteristics in order to disclose how far one assemblage isfrom the other.