SDHB and infection: Besides the up-regulation of genes involved in anaerobic glycolysis, the microarray data showed that among the genes encoding components of the TCA (tricarboxylic acid) cycle, transcription of three enzymes-encoding genes, the isocitrate dehydrogenase (Idh1), the succinate dehydrogenase (Sdhb) and the fumarate hydratase (Fh1), was downregulated during infection (Figure 3).