Physiological and morphological characters in two pyrimethamine-resistant lines of Plasmodium berghei SP11 after cryopreservation.

The authors describe the characters in two pyrimethamine-resistant lines of Plasmodium berghei berghei SP 11-RR after long storage at very low temperatures. In one case the line had maintained its original virulence but lost its resistance to pyrimethamine. Gametocytogenesis increased and cyclical transmission was successful.