Selection and validation of candidate reference genes for quantitative real-time PCR studies in the shrimp Penaeus vannamei under viral infection.

The decapod Penstyldensovirus 1 (PstDV-1) represents one of the most serious threats for penaeid shrimp farming. Studies aimed at defining relevant molecular effects of this virus over its host are imperative in the attempt to increase our understanding of its pathogenesis. Unfortunately, few studies have focused on the definition of the expression profile of reference genes in shrimp challenged with a pathogen. As a result, there are no studies on the selection of reference genes for the normalization of target gene expression changes yielding reliable data of the effects following PstDV-1 infection in shrimp. Therefore, the aim of the present study was to evaluate and validate the appropriateness of four candidate reference genes (ef1-α, gapdh, rpl8 and β-tubulin) for their use as reference genes to normalize qPCR data in gene expression studies of PstDV-1-shrimp interactions. By analyzing the expression profile of those genes, gapdh was validated as a suitable reference gene to normalize expression data gathered from a PstDV1-challenge, while ef1-α, β-tubulin, and rpl8 were identified as unstably expressed during the infectious process. The suitability of gapdh as a common reference gene in studies of host gene response to viral infections is underlined.