Entamoeba histolytica: cysteine proteinase activity and virulence. Focus on cysteine proteinase 5 expression levels.

Cysteine proteinase (CP) activity and CP5 mRNA levels were analyzed in eleven samples of Entamoeba histolytica isolated from patients presenting different clinical profiles. The virulence degree of the isolates, determined in hamster liver, correlated well with the clinical form of the patient and culture conditions. CP5 mRNA levels were also determined in sample freshly picked up directly from liver amoebic abscess.