??????????????????????????? Spatzle ???????????????????????? Vibrio parahaemolyticus ?????????

Abstract

The white shrimp (Litopenaeus vannamei) is a key species in the aquaculture industry, contributing significantly to Thailand's economy. However, being an imported species, white shrimp are more vulnerable to pathogen infections, which can have a substantial economic impact. The Sp�tzle protein plays an essential role in the shrimp's immune response through the Toll signaling pathway. Upon pathogen invasion, receptor proteins recognize the pathogen's cell surface structure, triggering the binding of Sp�tzle to the Toll receptor. This activates a signaling cascade that leads to the production of antimicrobial peptides (AMPs), which are vital for pathogen elimination. In this research, four Sp�tzle genes from white shrimp-LvSpz1, LvSpz2, LvSpz3, and LvSpz4-were investigated to determine their roles in antimicrobial peptide (AMP) biosynthesis signaling during infection with Vibrio parahaemolyticus. These Sp�tzle genes were found to be expressed across all examined tissues, each displaying distinct expression profiles. LvSpz1 and LvSpz3 showed the highest expression levels in the gills, LvSpz2 was highly expressed in the hepatopancreas and hemocytes, while LvSpz4 was predominantly expressed in hemocytes. After RNA interference (RNAi) experiments, the expression levels of LvSpz1 were reduced by more than 80%, while the expression levels of LvSpz2, LvSpz3, and LvSpz4 were reduced by more than 70%. Additionally, in LvSpz-silenced shrimp exposed to V. parahaemolyticus, the silencing of LvSpz2 resulted in a shrimp mortality rate of up to 80% within 12 hours of infection, reaching 100% at 24 hours. Further investigations revealed that LvSpz2 silencing significantly reduced the expression of LvToll1, LvToll9, LvNF-?B, and LvALF1. Notably, LvToll1 and LvALF1 were downregulated by more than 50% compared to baseline levels. These findings indicate that LvSpz2 regulates the expression of antimicrobial peptides, such as LvALF1, through the Toll pathway.

??????? (Litopenaeus vannamei) ?????????????????????????????????????????????????????????? ?????????????????????????????????????????? ????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????? ?????? Sp�tzle ????????????????????????????????????????????????????? Toll signaling pathway ????????????????????????????? ???????????????????????????????????????????????? ?????????????????????????? Sp�tzle ????????? Toll ???????????????????????????????????????????????????????????? (AMPs) ????????????????????????????????? ????????????????????????????? Sp�tzle ????????????????? ?????? LvSpz1, LvSpz2, LvSpz3 ??? LvSpz4 ??????????????????????????????????????????????????????????????????????????????????????????????????????? Vibrio parahaemolyticus ??????????????????????????? Sp�tzle ??????????????????????????????????????????????????????????? ??????????????????????????????????????????????? LvSpz1 ??? LvSpz3 ?????????????????????????? LvSpz2 ??????????????????????????????? ???????? LvSpz4 ???????????????????????? ??????????????? RNA interference (RNAi) ?????????????????? LvSpz1 ??????????? 80% ???????????????????????? LvSpz2, LvSpz3 ??? LvSpz4 ??????????? 70% ????????????????????? LvSpzs ????????????????????????????????????? V. parahaemolyticus ?????????????????????????? LvSpz2 ?????????????????????????????????????????? 80% ????? 12 ?????????????????????? ???????????????? 100% ????? 24 ??????? ??????????????????????????????????????????????? LvSpz2 ????????????????????? LvToll1, LvToll9, LvNF-?B ??? LvALF1 ??????????????????? ????????????????? LvToll1 ??? LvALF1 ??????????????????????? 50% ?????????????????????? ??????????????????????????? LvSpz2 ???????????????????????????????????????????????????? ???? LvALF1 ????????????????? Toll signaling pathway