Differentiation, multiplication and control of bloodstream form Trypanosoma (Duttonella) vivax in mice.
The growth and differentiation of Trypanosoma vivax was studied in intact and irradiated C3H/He and C57Bl/6 mice. In irradiated (800 R) or intact C3H/He and irradiated (800 R) C57Bl/6 mice, T. vivax parasitaemia increased rapidly then entered a plateau phase and thereafter declined in an antibody-independent remission phase. Throughout the infection, variations were observed in parasite morphology, density, DNA content, number of organisms with 2 nuclei and 2 kinetoplasts and infectivity of parasites for mice. Parasites in exponential phase had the highest number of members in the S, G2 and M phases of the cell cycle as determined by staining with the interchalating dye Chromomycin A3 and analysis on a flow cytometer. During this phase there were numerous parasites with 2 nuclei and 2 kinetoplasts and infectivity was high for mice. As the parasitaemia approached and entered the plateau phase, the proportion of organisms in the S, G2 and M phases of the cell cycle as well as the number of those with 2 kinetoplasts decreased slightly; the number of organisms with 2 nuclei decreased rapidly; and parasites had a considerably reduced capacity to infect mice. Organisms from the remission phase contained only 1 nucleus and 1 kinetoplast and were not infective for mice. The study suggests that T. vivax organisms transit from dividing to committed non-dividing forms and that some non-diving, non-infective T. vivax organisms remain trapped in the S, G2 and M stages of the cell cycle and die without completing binary fission.(ABSTRACT TRUNCATED AT 250 WORDS)
ILRAD, Nairobi, Kenya.
S M
SM
Mahan
S J
SJ
Black
D000818:Animals; D002453:Cell Cycle; D004247:DNA / Q000032:analysis; D005260:Female; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D014345:Trypanosoma / Q000254:growth & development*; D014353:Trypanosomiasis, African / Q000097:blood / Q000469:parasitology*
D004247:DNA