Infection of unvaccinated mice with P. chabaudi appeared to cause a slight decrease in Mpl transcripts on day 4 p.i., before Mpl expression continuously increased, reaching its highest levels, 31, towards the end of the crisis phase on day 11 p.i. In contrast to unvaccinated mice, malaria infection caused an almost linear increase in hepatic Mpl expression of vaccinated mice on day 4 p.i., before reaching about the same maximum level on day 11 p.i. as that of unvaccinated mice. Here, MPL is linked to infection.