FIG 2.

Vaccine-induced protection against homologous and heterologous strain challenge. After three doses of 10⁶ chemically treated P. yoelii 17X pRBCs or nRBCs, BALB/c mice were challenged with 10⁵ P. yoelii 17X pRBCs (left panels) or P. yoelii YM pRBCs (right panels). After challenge, parasitemias (A and B), hemoglobin levels (C and D), clinical scores (E and F), and survival (G and H) were assessed. The vaccinated group challenged with P. yoelii 17X contained nine mice; all other groups contained ten mice. Error bars represent the SEM for each group. +, mice that succumbed to infection. Peak parasitemia was significantly lower in vaccinated mice than in control mice when challenged with homologous or heterologous parasites (****, P < 0.0001). Data were analyzed using an unpaired, two-tailed t test.