Leishmania mexicana mexicana: quantitative analysis of the intracellular cycle.
The complete intracellular cycle of the Leishmania mexicana mexicana G. S. strain was quantified in human macrophages and in the mouse IC-21 macrophage line utilizing a culture system that allows the direct observation of individual intracellular parasites. A wide range of pre-replicative lag periods exists, implying that promastigotes may be in any phase of their DNA synthetic cycle when phagocytosed by the macrophage. Amastigotes replicated 2-3 times, after which the host cell died and liberated amastigotes that were taken up by other macrophages and continued to replicate. The mean amastigote population-doubling time in human macrophages (17.5 h) was not statistically different from promastigotes growing in axenic culture (16.4 h), but was nearly 2-fold less than amastigotes growing in mouse-derived IC-21 macrophages (33.7 h). These observations are markedly different from cover-glass culture assays of Leishmania-macrophage interactions and provide an unambiguous description of the intracellular cycle of Leishmania mexicana mexicana.
Doyle
P S
PS
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
Engel
J C
JC
Gam
A A
AA
Dvorak
J A
JA
D000818:Animals; D004247:DNA / Q000096:biosynthesis; D006801:Humans; D007894:Leishmania mexicana / Q000254:growth & development*; D008264:Macrophages / Q000469:parasitology; D051379:Mice; D008810:Mice, Inbred C57BL
D004247:DNA