Temperature adaptation of Entamoeba histolytica and its effect on virulence

Abstract

1. 1. Three strains (UC, 201, and 202) of E. histolytica were adapted to grow at low (29 [deg]C) and high (42.5 [deg]C) temperatures.2. 2. Encystment of strains 201 and UC was produced by returning the trophozoites from the temperatures of adaptation to the original normal growth temperature of 37 [deg]C.3. 3. Unadapted strains 201 and 202 of E. histolytica had a low degree of virulence for livers of hamsters, while the same strains adapted to low temperature were highly virulent.4. 4. The virulence of these adapted amebae was not lost by returning these parasites to their original normal growth temperature of 37 [deg]C for 6 weeks.5. 5. By adding the bacteria of the adapted culture to the unadapted amebae, a moderate increase in the virulence was produced.