Cloning and characterization of Plasmodium falciparum FCR-3/FMG strain
Green, T.J.; Gadsden, G.; Seed, T.; Jacobs, R.; Morhardt, M.; Brackett, R.
American Journal of Tropical Medicine and Hygiene 34(1): 24-30
1985
ISSN/ISBN: 0002-9637 PMID: 3882009 Document Number: 255552
The FCR-3/FMG African strain of P. falciparum was cloned by the limiting dilution technique of in viro culture (Trager and Jensen culture method performed in microtitre plates) to obtain parasite populations derived from a single cell. The cloning sequence was repeated serially 3 times, and 3 parasite clones with a >99% probability of single cell derivation were isolated. Electron microscopy of these clones showed that one (C-6) was distinct from the other two (C-3 and C-5) and the parent strain in lacking surface knobs (K-). The clones were equally sensitive to chloroquine in vitro, but varied in their pathogenicity to Aotus trivirgatus griseimembra, the K- clone being less pathogenic than the K+ clones. Several studies have now shown that Plasmodium falciparum parasites in a single patient comprise a mixture of more than one genetically distinct organism. In this study, clones of the FCR-3/FMG strain of P. falciparum were producd in culture by limiting dilution. Recloning was carried out to ensure that the clones were pure. Three such clones were then studied. Each proved to be equally sensitive to chloroquine. Two exhibited knobs on the surface of parasitized erythrocytes; the third was knobless. Some differences between the growth rates of each clone were also noted, both in culture and in infections in Aotus monkeys.D. Walliker.