10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 4 2012(October - December) Toll protein is an important non-specific immune protein in crustaceans which rely on innate immunity. The expression of Toll protein gene was studied in healthy and experimentally exposed ( lessThan i greaterThan Vibrio harveyi lessThan /i greaterThan ) lessThan i greaterThan Penaeus monodon lessThan /i greaterThan (tiger shrimp) by reverse transcriptase polymerase chain reaction (RT-PCR) using self-designed Toll-specific PCR primers. Comparison of the expression profiles of Toll protein gene in gills, hepatopancreas and gut of lessThan i greaterThan P.monodon lessThan /i greaterThan showed that experimental exposure to a gram-negative bacterial pathogen, lessThan i greaterThan Vibrio harveyi lessThan /i greaterThan induces Toll protein gene expression in these organs. The identity of the PCR amplified lessThan i greaterThan P.monodon lessThan /i greaterThan Toll protein gene was confirmed by nucleotide sequencing and analysis A.UMA, A.H.M. HARRESH AND G.REBECCA Penaeus monodon – Toll protein gene expression – RT-PCR. 316-320