10.22376/ijpbs.2019.10.1.p1-12 Volume 4 Issue 1 2013 (January - March) Toll proteins are components of innate immune system known to be involved in the recognition of pathogen associated molecular patterns (PAMPs), the conserved motifs of the pathogens and in eliciting the immune response. This study was carried out with an objective to identify the expression of Toll protein gene in lessThan i greaterThan Litopenaeus vannamei lessThan /i greaterThan and to compare its expression profiles in healthy and experimentally induced status lessThan i greaterThan . L.vannamei lessThan /i greaterThan was experimentally induced by exposure to lessThan i greaterThan Vibrio alginolyticus lessThan /i greaterThan at a concentration of 9×10 lessThan sup greaterThan 12 lessThan /sup greaterThan colony forming units/ml (CFU ml lessThan sup greaterThan -1 lessThan /sup greaterThan ). Tissues of various organs lessThan i greaterThan viz lessThan /i greaterThan ., muscle, gut, gills, heart, nerve and pleopods of lessThan i greaterThan L.vannamei lessThan /i greaterThan that were healthy and experimentally exposed with lessThan i greaterThan V.alginolyticus lessThan /i greaterThan were used to study the toll protein gene expression profile by Reverse transcriptase Polymerase chain reaction (RT- PCR). Basal expression of toll protein gene at various levels was observed in muscle, gut, gills, heart, nerve and pleopods of healthy lessThan i greaterThan L. vannamei lessThan /i greaterThan . Comparatively higher levels of toll protein gene expression were observed in the tissues of lessThan i greaterThan L. vannamei lessThan /i greaterThan that were experimentally exposed with lessThan i greaterThan V.alginolyticus, lessThan /i greaterThan the highest induced expression level was recorded in the nerve tissue. SOWMYA. M.V, UMA. A AND REBECCA. G Litopenaeus vannamei, toll protein, expression, experimental induction, Vibrio alginolyticus. 592-595