Genome-wide identification of toll-like receptors in Pacific white shrimp (Litopenaeus vannamei) and expression analysis in response to Vibrio parahaemolyticus invasion

Genes encoding for Toll-like receptors (TLRs) provide innate immunity to aquatic organisms. The function of TLRs in innate immunity has been characterized in several crustacean species; however, systematic information on TLRs is still scarce in the Pacific white shrimp (Litopenaeus vannamei). Here, we conducted a genome-wide study of TLR genes for the first time in Pacific white shrimps. A total of 11 TLR genes were recognized. Analysis of the architecture domain revealed that most TLR genes possessed three major domains: a Toll/interleukin receptor (FIR) domain, a transmembrane domain (FM), and multiple leucine-rich repeat domains (LRRs). Results revealed that all 11 TLR genes were ubiquitously expressed in all the tested tissues. Furthermore, the expression of 11 TLR genes after Vibrio parahaemolyticus infection was measured in hemocytes, hepatopancreas, and gills. The results showed that most genes were significantly up regulated at different time points, except for TLR-Tollo1 and TLR-Tollo2 in hepatopancreas, and TLR13 x isoform, TLR3, TLR4, and PTL-2 in gills. Our study provided the first genome-wide systemic analysis of Pacific white shrimp and suggested that TLR genes play significant roles in the L. vannamei immune response. These findings will offer evidence for the functional study of L. vannamei TLRs and could facilitate the investigation of molecular mechanisms underlying the immune regulation of L. vannamei challenged by V. parahaemolyticus, which will consequently contribute to the sustainability of aquaculture.

Automated summary

This study conducted a genome-wide study of Toll-like receptor genes in Pacific white shrimps for the first time, identifying 11 TLR genes. The majority of these genes were found to be ubiquitously expressed in various tissues and significantly upregulated at different time points after infection, suggesting their significant roles in the immune response of Litopenaeus vannamei.