TABLE 4.

Anti-PyCSP antibody-treated sporozoites fail to invade liver^a

Mouse group used as serum source	Type of serum used to treat sporozoites	No. of P. yoelii 18S rRNA copies in livers of challenged mice (geometric mean ± SEM)
Protected	Wild-type immunized mouse sera	2.935 ± 0.66
Nonprotected	Normal sera	10,135 ± 389
Uninfected		0.0665 ± 0.05

^aNaive BALB/c mice were injected with P. yoelii 17XNL sporozoites treated for 45 min with sera from rPyCSP-immunized mice that had sterilizing immunity following sporozoite challenge. Livers were harvested 40 h postchallenge for detection and quantification of the P. yoelii 18S rRNA to measure the developing liver stage parasite burden. RNA was isolated, and reverse transcription-quantitative PCR amplification for 18S RNA was performed.