The T cell factor, pangolin, from Litopenaeus vannamei play a positive role in the immune responses against white spot syndrome virus infection.

As a downstream interactor of β-catenin, Pangolin which is the homologous protein of the T cell factor/lymphoid enhancer factor (TCF/LEF) in vertebrates is less understood in the research field of immunity. In this study, two isoforms of Litopenaeus vannamei Pangolin (LvPangolin1 and LvPangolin2) were identified. Phylogenetic tree analysis revealed that all of the Pangolin proteins from invertebrates were represented the same lineage. The mRNA expression profiles of the LvPangolin1 and LvPangolin2 genes differed across different tissues. The expression of LvPangolin1 and the amount of LvPangolin1and LvPangolin2 combined (LvPangolinComb) were significantly increased in the haemocyte, intestine and gill but reduced in the hepatopancreas after white spot syndrome virus (WSSV) challenge. The inhibition of LvPangolin1 but not LvPangolinComb significantly reduced the survival rates of L. vannamei after WSSV infection, while significantly higher WSSV viral loads in both LvPangolin1-inhibited and LvPangolinComb-inhibited L. vannamei were observed. Knockdown of LvPangolin by RNAi could distinctly decrease the expression of antimicrobial peptide (AMP) genes and their related transcription factors. All of these results indicate that LvPangolin plays a positive role in the response to WSSV infection and that this may be mediated through regulating the immune signalling pathways which control the expression of AMPs with antiviral abilities.

Zhu L ，Zhang S ，Hou C ，Liang X ，Saif Dehwah MA ，Tan B ，Shi L ... -  《-》

Molecular and immune response characterizations of a novel AIF and cytochrome c in Litopenaeus vannamei defending against WSSV infection.

Apoptosis inducing factor (AIF) and cytochrome c (CYC) are two mitochondrial apoptogenic factors. In the present study, the cDNA sequences of AIF (LvAIF) and CYC (LvCYC) were cloned from Pacific white shrimp, Litopenaeus vannamei. The LvAIF was 1664 bp, including a 5'-terminal untranslated region (UTR) of 154 bp, an open reading frame (ORF) of 1323 bp encoding a polypeptide of 440 amino acids (aa) and a 3' UTR of 187 bp. The LvCYC was 582 bp, including a 50 bp 5' UTR, a 315 bp ORF encoding for 104 aa, and a 217 bp 3' UTR. The deduced protein of LvAIF contained a conserved Pyr_redox and AIF_C domain at the N-terminal and the predicted LvCYC included a conservative cytochrome_C domain, respectively. Phylogenetic analysis revealed that LvAIF belonged to AIF1 subfamily and showed a close relationship with AIF1 from vertebrates and LvCYC showed the closest relationship with its counterparts from shrimp Marsupenaeus japonicus. Tissue expression profiles showed that both LvAIF and LvCYC existed in most tissues, with the most predominant expression of LvAIF in intestine, then followed muscle and the weakest expression in gill. The highest expression of LvCYC was detected in muscle, and the weakest expression was in hemocytes. Additionally, after white spot syndrome virus (WSSV) infection, the significant up-regulation of LvAIF, LvCYC and caspase 3 transcripts and the increase of pro-caspase 3 and active-caspase 3 protein were detected at most time points (P < 0.05). However, all of the three genes down-regulated in hemocytes in the early stage after WSSV infection. WSSV proliferation and shrimp mortality showed a time-dependent manner and the production of ROS in hemocytes were significantly increased at 6 and 24 h after infection. Our results showed that the apoptotic genes AIF, CYC and caspase 3 might play crucial roles in hepatopancreas, however, the production of ROS in hemocytes might be important in shrimp defense against WSSV infection.

Hu WY ，Yao CL 《-》

Molecular characterization of a novel white spot syndrome virus response protein (dubbed LvWRP) from Litopenaeus vannamei.

White spot syndrome, which is caused by white spot syndrome virus (WSSV), is a highly contagious disease of penaeid shrimp. However, there is currently incomplete understanding of the infection mechanism and pathogenesis of WSSV. In this study, a novel gene of a previously uncharacterized WSSV response protein (LvWRP) in Litopenaeus vannamei was identified and characterized. The LvWRP gene has an open reading frame (ORF) of 879 bp encoding a putative protein of 292 amino acids. Sequence analysis revealed that LvWRP shared 24.9% identity with an uncharacterized protein of Penaeus monodon nudivirus. Real-time qPCR analysis showed that LvWRP was ubiquitously expressed in shrimp tissues, with transcript levels induced in hemocytes upon immune challenge with Vibrio parahaemolyticus, Streptoccocus iniae, lipopolysaccharide (LPS), and WSSV. In addition, RNA interference-mediated knockdown of LvWRP followed by WSSV challenge revealed significant decrease in the transcript levels of WSSV IE1 and VP28 genes coupled with a reduction in WSSV copies in shrimp hemocytes. Moreover, depletion of LvWRP followed by WSSV challenge significantly increased the transcript levels of Vago4 and Vago5 as well as increased the phosphorylation of STAT, while hemocytes apoptosis in terms of caspase 3/7 activity was decreased. These results suggest that LvWRP is important for WSSV replication in shrimp, and therefore one of the vital host factors in WSSV infection.

Gao G ，Lin R ，Tao M ，Aweya JJ ，Yao D ，Ma H ，Li S ，Zhang Y ，Wang F ... -  《-》

Sequencing and de novo analysis of the hemocytes transcriptome in Litopenaeus vannamei response to white spot syndrome virus infection.

Xue S ，Liu Y ，Zhang Y ，Sun Y ，Geng X ，Sun J ... -  《PLoS One》

Cloning of Litopenaeus vannamei CD63 and it's role in white spot syndrome virus infection.

White Spot Syndrome Virus (WSSV) is currently the most serious shrimp pathogen, which has brought huge losses to shrimp industry worldwide. CD63 of shrimp belongs to the tetraspanin superfamily, which plays an important role in signal transduction and immune process. In this paper, CD63 cDNA sequence of Litopenaeus vannamei was cloned using RACE method. The amplified sequence is 1472 bp, with its ORF 744 bp, encoding 247 amino acids. Bioinformatics analysis showed that the sequence of LvCD63 has 93% similarity with Penaeus monodon and 92% similarity with Fenneropenaeus chinensis. Real-time PCR analysis showed that the mRNA levels of LvCD63 expressed in the tissues of hemocytes, gill, epithelial tissue, heart, lymphoid, hepatopancreas, stomach, intestines, muscle and nerve. Among these tissues the highest expression level was showed in the tissue of haemolymph, followed by epithelial tissue, hepatopancreas, and nerve. The lowest expression level of LvCD63 was appeared in the muscle tissue. After WSSV challenge, the expression levels of LvCD63 were both up-regulated in the tissues of gill and epithelial. However the expression level of LvCD63 in hepatopancreas was down-regulated. Far-western blot analysis showed that LvCD63 interacts with VP28, and both VP28N and VP28C fragments interact with LvCD63. Flow cytometry analysis showed that LvCD63 was present on the surface of hemocytes and it is required for binding of WSSV virions. Neutral experiments in vivo showed that LvCD63LEL delayed WSSV infection in shrimp.

Guan GK ，Liu QH ，Li C ，Huang J ... -  《-》