CHLOROQUINE ENCAPSULATED IN MALARIA-INFECTED ERYTHROCYTE-SPECIFIC ANTIBODY-BEARING LIPOSOMES EFFECTIVELY CONTROLS CHLOROQUINE-RESISTANT PLASMODIUM-BERGHEI INFECTIONS IN MICE

The suitability of liposomes as drug carriers in the treatment of drug -resistant rodent malaria was examined after covalently attaching F(ab ')(2) fragments of a mouse monoclonal antibody (Mab), MAb F-10, raised against the host cell membranes isolated from the Plasmodium berghei- infected mouse erythrocytes, to the liposome surface. The antibody-bea ring liposomes thus formed specifically recognized the P. berghei-infe cted mouse erythrocytes under both in vitro and in vivo conditions. No such specific binding of the liposomes with the infected cells was ob served when MAb F-10 was replaced by another mouse monoclonal antibody , MAb D-2. Upon loading with the antimalarial drug chloroquine, the MA b F-10-bearing liposomes effectively controlled not only the chloroqui ne-susceptible but also the chloroquine-resistant P. berghei infection s in mice. The chloroquine delivered in these liposomes intravenously at a dosage of 5 mg/kg of body weight per day on days 4 and 6 postinfe ction completely cured the animals (75 to 90%) of chloroquine-resistan t P. berghei infections. These results indicate that selective homing of chloroquine to malaria-infected erythrocytes mag help to cure the c hloroquine resistant malarial infections with low doses of chloroquine .