Quantitative Real-Time PCR Analysis of Gene Expression Levels in IHHNV-infected Pacific Blue Shrimp

The innate immune response is the rapid, non-specific, first line of defense against foreign agents. Genes coding for immune-related proteins express differentially during the cellular and humoral immune response in order to clear a pathogen. We are examining the genetic response in an invertebrate system, which only contains an innate immune system, to potential infection by the Infectious Hypodermal and Hematopoietic Necrosis virus (IHHNV). Our host is the Pacific blue shrimp, Litopenaeus stylirostris. A previously generated SAGE library revealed hundreds of immune-related genes in our shrimp differing in expression levels between control (non-infected) and experimental (INNHV-infected) samples, one-day post infection. To validate this expression library we performed quantitative real-time PCR (qPCR) assays to determine relative transcript expression levels of a set of immune-related genes. We expected at one-day post infection, control and IHHNV-infected shrimp cDNA would have differential expression patterns. Relative quantification of eight immune-related genes (defender against cell death-1, histone h2a member z, HSP-70, seleno-h, arginine kinase, cyclophilin-a, viral a-type inclusion protein, and IHHNV) was examined. Our data revealed differential fold changes between groups. The qPCR research will expand to include other genes; including those involved in various immune-related mechanisms such as apoptosis, and we plan to analyze gene expression levels across other time points post viral infection. The global objective is twofold; we aim to further contribute to the overall understanding of innate immunity at the genetic level and identify potential gene targets to combat against viral infection to decrease economic loss for farms that harvest this shrimp.