Virulent and avirulent Entamoeba histolytica and E. dispar differ in their cell surface phosphorylated glycolipids

Virulent strains of Entamoeba histolytica have been reported to produce a mixture of phosphoglycoconjugates that share some structural features with the lipophosphoglycans (LPGs) of Leishmania. Purification of these glycoconjugates is essential to their precise structural characterization. In this study we have extracted ‘LPG-like’ molecules from various virulent E. histolytica strains and purified on the basis of charge differences, 2 apparently related glycoconjugates a ‘LPG’ and a ‘lipophosphopeptidoglycan (LPPG)’. In marked contrast to the abundance of these ‘LPG’ and ‘LPPG’ molecules in the virulent strains, avirulent E. histolytica and E. dispar strains produce either very low, or no detectable levels of LPG, and either low levels or modified forms of ‘LPPG’. Monospecific polyclonal antibodies prepared against that ‘LPG’ of the virulent strain HM-1: IMSS cl6 identified epitopes shared between both the ‘LPG’ and the ‘LPPG’ of this and other virulent strains, using Western blot analysis. Flow cytometric analysis of a range of strains using these antibodies identified a surface distribution of these molecules and confirmed a correlation between surface exposure of epitopes bound by these antibodies and parasite virulence.