EFFECT OF PYRIMETHAMINE RESISTANCE ON SPOROGONY IN A PLASMODIUM-BERGHEI ANOPHELES-STEPHENSI MODEL

A pyrimethamine-resistant line of Plasmodium berghei was derived by tr eating infected mice with high doses of pyrimethamine and selecting fo r recrudescence. This resistant line was compared with the parental py rimethamine-sensitive line in order to ascertain whether drug resistan ce is associated with a biological advantage. Overall, the pyrimethami ne-resistant line is quite similar to the sensitive line, except that it proceeds through sporogonic development more slowly than the pyrime thamine-sensitive parental line. However, under pyrimethamine pressure the sensitive line is unable to undergo the sporogonic cycle, whereas the resistant line is unaffected. These results indicate that the tra nsmission of pyrimethamine resistance in this model is favored only un der conditions of drug pressure. (C) 1994 Academic Press, Inc.