Epigenetic modifications of gene promoters in the liver of Balb/c mice protected by vaccination against blood-stage malaria of Plasmodium chabaudi. Mus musculus

Protective vaccination induces survival of more than 80% of female Balb/c mice otherwise succumbing to blood-stage malaria of Plasmodium chabaudi. This study investigates the effect of protective vaccination and P. chabaudi infections on DNA methylation of gene promoters in the liver of Balb/c mice. Using DNA methylation microarrays, protective vaccination is shown to affect per se the constitutive DNA methylation status of numerous gene promoters in the liver: Promoters of 256 genes are hyper(=up)- and 345 genes are hypo (=down)-methylated at a significance of p<0.05. Gene enrichment analysis reveals that genes with down-methylated promoters are most statistically significant enriched (p<0.01) with functions related to negative regulation of transcription, whereas genes with up-methylated promoters are related to positive regulation of transcription and immune system. Infections with P. chabaudi also induce changes in promoter DNA methylation. In vaccinated mice, these changes are observable already on day 1 p.i. and, in particular, at peak parasitemia on day 8 p.i., when 571 and 1013 gene promoters have become up- and down-methylated, respectively, in relation to constitutive DNA methylation at a signicance level of p<0.05. The corresponding gene promoters in non-vaccinated mice are also responsive to infection, but by far not as pronounced as in vaccinated mice. Our data demonstrate that vaccination modifies DNA methylation of gene promoters in the liver and augments promoter responsiveness to infection-induced DNA methylation alterations, which ultimately control expression of those genes in the liver required for survival of otherwise lethal blood-stage malaria of P. chabaudi. Overall design: 18 samples were analyzed; Nd0, Non-vaccinated day 0, 3 replicates Vd0, Vaccinated day 0, 3 replicates Nd1, Non-vaccinated day 1, 3 replicates Vd1, Vaccinated day 1, 3 replicates Nd8, Non-vaccinated day 8, 3 replicates Vd8, Vaccinated day 8, 3 replicates