CASP9 and infection: A total of eleven differentially expressed genes (NFκB, IL6, IRF3, IL1β, TNF, RIP2, CASP9, IRAK4, IL6, RIP1 and NOD) having an important role in the cross talk across different signaling pathways were validated for their expression using real time RT-PCR in spleen, liver and lung at both early and late stages of infection (Fig 5).