AUTHOR=Huang Ying , Chen Yihong , Hui Kaimin , Ren Qian 

TITLE=Cloning and Characterization of Two Toll Receptors (PcToll5 and PcToll6) in Response to White Spot Syndrome Virus in the Red Swamp Crayfish Procambarus clarkii

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.00936

DOI=10.3389/fphys.2018.00936

ISSN=1664-042X

ABSTRACT=<p>Toll/Toll-like receptors are key components in the innate immune responses of invertebrates. In this study, we identified two novel Toll receptors (<italic>PcToll5</italic> and <italic>PcToll6</italic>) from the red swamp crayfish <italic>Procambarus clarkii</italic>. The complete cDNA sequence of <italic>PcToll5</italic> is 4247 bp, encoding a 1293 amino acid polypeptide. The full-length 4688 bp <italic>PcToll6</italic> encodes a putative protein of 1195 amino acids. Quantitative RT-PCR analysis indicated that <italic>PcToll5</italic> and <italic>PcToll6</italic> were constitutively expressed in all tissues studied. The highest expression levels of <italic>PcToll5</italic> and <italic>PcToll6</italic> were found in the intestine and gills, respectively, and were significantly upregulated from 24 to 48 h during white spot syndrome virus (WSSV) challenge. siRNA-mediated RNA interference results showed that <italic>PcToll5</italic> and <italic>PcToll6</italic> might regulate the expression of anti-lipopolysaccharide factors (<italic>PcALF2</italic> and <italic>PcALF3</italic>) <italic>in vivo</italic>. Overexpression of PcToll5 and PcToll6 in <italic>Drosophila</italic> Schneider 2 (S2) cells activated the transcription of <italic>Drosophila</italic> antimicrobial peptides, including <italic>drosomycin</italic> (<italic>Drs</italic>), <italic>metchnikowin</italic> (<italic>Mtk</italic>), and <italic>attacin A</italic> (<italic>AttA</italic>), and shrimp <italic>Penaeidin</italic>-4 (<italic>Pen4</italic>). These findings provide significant information that <italic>PcToll5</italic> and <italic>PcToll6</italic> may contribute to host immune defense against WSSV in <italic>P. clarkii</italic>.</p>