This book is concerned with the effect of three human respiratory viral infections (Influenza vieus, Parainfluenza virus and Adeno virus) on immune gene expression. It provides protocols for DNA and RNA extraction, PCR technique, Real Time Reverse Transcriptase PCR, and RT-PCR Array. It includes Gene ontology analysis to determine the functions of affected genes, the gene sites in key immune pathways, viral cluster through affected genes and gene expression profile after viral infections.