LAUSR

Abstract As a consequence of axenic growth and the elimination of accompanying bacterial flora, Entamoeba histolytica virulence decreases rapidly, and pathogenicity is lost. This paper evaluated the impact of vitamin supplementation on the pathogenicity of E. histolytica. Growth of E. histolytica trophozoites, cultured axenically in PEHPS (a Spanish acronym for the main ingredients – casein peptone, liver, pancreas extract and bovine serum) medium, with or without vitamins, exhibited a similar growth rate. However, the vitamin-enriched PEHPS preparations expressed 2.65 times more haemolytic activity (at 60 min: 98 vs 48%, P < 0.05), 2.5 times more phospholipase A2 activity at 150 min of incubation and generated more hepatic abscesses (88 vs 60%, P = 0.05) than the preparations without vitamins. The haemolytic and phospholipase A2 activity for the PEHPS − V preparations were restored following vitamin supplementation with A and D. These data highlight, for the first time, that vitamins and specifically vitamin A and D were essential for the recovery of amoebic virulence, lost through axenic growth.