[A comparison of the efficiency of density gradient and low-speed centrifugation methods for isolating Plasmodium...

P. yoelii sporozoites(Sp) in Anopheles stephensi were first isolated with low-speed centrifugation and the Sp suspension was subsequently purified with the density gradient centrifugation. The recovery rates of Sp by the latter method is about 50 approximately 75% of that by the former, but few debris could be found in the Sp suspension and the infectivity of the Sp was not weakened as compared with the Sp obtained by low-speed method. Sp would retain partial infectivity, when its suspension was maintained in medium 199 at 4 degrees C for 48 hrs. When rats and mice were infected with these Sp, pathological changes of hepatocytes such as cloudy swelling or fatty degeneration, which had been evidenced to be induced by mosquito tissues, would be absent or present in the slightest degree.