Reference gene selection for normalization of PCR analysis in chicken embryo fibroblast infected with H5N1 AIV

Chicken embryo fibroblasts (CEFs) are among the most commonly used cells for the study of interactions between chicken hosts and H5N1 avian influenza virus (AIV). In this study, the expression of eleven housekeeping genes typically used for the normalization of quantitative real-time PCR (QPCR) analysis in mammals were compared in CEFs infected with H5N1 AIV to determine the most reliable reference genes in this system. CEFs cultured from 10-day-old SPF chicken embryos were infected with 100 TCID(50) of H5N1 AIV and harvested at 3, 12, 24 and 30 hours post-infection. The expression levels of the eleven reference genes in infected and uninfected CEFs were determined by real-time PCR. Based on expression stability and expression levels, our data suggest that the ribosomal protein L4 (RPL4) and tyrosine 3-monooxygenase tryptophan 5-monooxygenase activation protein zeta polypeptide (YWHAZ) are the best reference genes to use in the study of host cell response to H5N1 AIV infection. However, for the study of replication levels of H5N1 AIV in CEFs, the β-actin gene (ACTB) and the ribosomal protein L4 (RPL4) gene are the best references.