Cysteine proteinase activity is required for survival of the parasite in experimental acute amoebic liver abscesses in hamsters.
Axenic trophozoites of Entamoeba histolytica strain HM1-IMSS grown in vitro in the presence of E-64, a potent irreversible inhibitor of cysteine proteinases, preserved their viability, their rate of replication, their resistance to complement, their haemolytic capacity and their ability to destroy target cells, despite complete inhibition of total cysteine proteinase activity. On the other hand, their erythrophagocytic capacity and their ability to decrease TER of MDCK cells was partially decreased. The same trophozoites injected into the portal vein of hamsters receiving a maintaining dose of E-64 failed to cause tissue damage and were rapidly eliminated. Our results suggest that amoebic cysteine proteinase activity is not required for amoebic functions in in vitro conditions, but that it becomes necessary for survival of trophozoites in in vivo conditions, whatever other role (if any) it may play in the parasite's virulence.
Olivos-García
A
A
Department of Experimental Medicine, National Autonomous University of Mexico Medical School, México City, México.
Tello
E
E
Nequiz-Avendaño
M
M
González-Canto
A
A
López-Vancell
R
R
García de León
M C
MC
Montfort
I
I
Pérez-Tamayo
R
R
D000818:Animals; D003165:Complement System Proteins / Q000378:metabolism; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D017097:Electric Impedance; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D004912:Erythrocytes / Q000469:parasitology; D005260:Female; D006651:Histocytochemistry; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008101:Liver Abscess, Amebic / Q000188:drug therapy / Q000469:parasitology*; D008297:Male; D010587:Phagocytosis
D015853:Cysteine Proteinase Inhibitors; D003165:Complement System Proteins; D003546:Cysteine Endopeptidases; D007930:Leucine; C024974:E 64