Table 1.

Relationship between DHFR point mutations in Kenyan field isolates of P. falciparum and in vitro chemosensitivity to the antifolates PM and CCG

DHFR phenotypeaIC50(n)b
PMCCG
Group 1
 108(−) 51(−) 59(−)3.71 ± 6.94 (5)0.24 ± 0.21 (5)
Group 2
 108(+) 51(−) 59(−)150.20 (1)0.81 (1)
 108(+) 51(+) 59(−)95.18 (1)1.38 (1)
 108(+) 51(−) 59(+)84.36 ± 12.5 (7)1.48 ± 0.94 (7)
  Total92.88 ± 36.02 (9)1.37 ± 0.85 (9)
Group 3
 108(+) 51(+) 59(+)815.25 ± 582 (18)10.80 ± 7.2 (18)
  • a 108(−), Ser-108 (wild type); 108(+), Asn-108; 51(−), Asn-51 (wild type); 51(+), Ile-51; 59(−), Cys-59 (wild type); 59(+), Arg-59.

  • b IC50s are expressed in nanomolar concentrations; values are means ± standard deviations;P < 0.01 for all values.