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The specific binding between viral attachment proteins (VAPs) of a virus and its cellular receptors on host cells mediates virus entry into host cells, which triggers subsequent viral infections. Previous studies indicate that F 1 ATP synthase β subunit (named BP53), is found on the surface of shrimp cells and involved in white spot syndrome virus (WSSV) infection by functioning as a potential viral receptor. Herein, in a far-western blotting assay, three WSSV proteins with molecular weights of 28 kDa, 37 kDa, and >50 kDa were found to interact with BP53. The 28 kDa and 37 kDa proteins were identified as the envelope protein VP28 and VP37 of WSSV respectively, which could be recognized by the polyclonal antibodies. Enzyme-linked immunosorbent binding assays revealed that VP37 contributed to almost 80% of the binding capability for BP53 compared with the same amount of total WSSV protein. The relationship between BP53 and its complementary interacting protein, VP37, was visualized using a co-localization assay. Bound VP37 on the cell surface co-localized with BP53 and shared a similar subcellular location on the outer surface of shrimp cells. Pearson’s correlation coefficients reached to 0.67 ± 0.05 and the Mander’s overlap coefficients reached 0.70 ± 0.05, which indicated a strong relationship between the localization of BP53 and bound rVP37. This provides evidence for an interaction between BP53 and VP37 obtained at the molecular and cellular levels, supporting the hypothesis that BP53 serves as a receptor for WSSV by binding to VP37. The identification of the viral binding proteins of shrimp BP53 is helpful for better understanding the pathogenic mechanisms of WSSV to infect shrimp at the cellular level. [ABSTRACT FROM AUTHOR]

WSSV is one of the most harmful pathogeny in the pacific white shrimp, and genetic variations caused the strains of different virulence. MicroRNAs (miRNAs) involved in the regulation of virus defense. To understand the different virulence of WSSV on miRNA expression in Litopeneaus vannamei , the deep sequencing was performed to compare two small RNA libraries prepared from hepatopancreas of Litopeneaus vannamei infected with normal-virulence or low-virulence WSSV. Approximately 29,398,623 raw reads from normal-virulence library and 35,291,803 raw reads from low-virulence library were obtained. There were about 37 miRNAs homologs identified. Sixteen miRNAs were significantly up-regulated and twenty-one miRNAs were significantly down-regulated in normal-virulence infection library compared with low-virulence infection library. Of these, Igi-miR-1175-3p was the most significant different miRNA, followed by bmo-miR-1175-3p and ipu-miR-26b, respectively. The putative target genes for differentially expressed miRNAs were concerned with biological processes, signal meditated, cell differentiation and apoptosis, immune recognition and other more functions. The results will help to understand the miRNAs response to different virulence WSSV infection. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) is the main pathogen of shrimp culture, and has brought great losses of the shrimp aquaculture industry every year since it has been found. However, the specific mechanism of the virus into the cell is not very clear. Recent research suggests that clathrin-mediated endocytosis is involved in WSSV infection. By sequence analysis, clathrin coat AP17 is an σ subunit of AP-2 complex which is involved in clathrin-mediated endocytosis. To obtain the full-length sequence of Clathrin coat AP17 of Litopenaeus vannamei ( LvCCAP17 ), the rapid amplification of cDNA ends (RACE) was performed to get the sequence of 3'and 5′ end and splicing by DNAMAN. The full-length sequence of LvCCAP17 is 842 bp and expected to encoding 142 amino acids, and the amino acid sequence was analyzed by online software. The mRNA expression of LvCCAP17 in different tissues was carried out with quantitative real-time PCR and the LvCCAP17 was detected in all tested tissues of Litopenaeus vannamei . The transcriptional expression level of LvCCAP17 in epithelium and hepatopancreas was significantly up-regulated after WSSV infection. Far-Western blotting and ELISA assay showed that LvCCAP17 interacted with rVP26 and rVP37. Silencing of LvCCAP17 gene by double-strand RNA (dsRNA) interference significantly delay of cumulative mortality rate in WSSV infected shrimp and reduced the expression level of immediate early gene 1 ( ie1 ) and vp28 . These results indicated that clathrin-meated endocytosis is responsible for WSSV infection. [ABSTRACT FROM AUTHOR]

Thioredoxin (TRX), a major intracellular antioxidant, has a wide range of biological functions. It was up-regulated and targeted by WSSV. However, the relevance of TRX with WSSV infection and signaling pathway remains largely unknown. Sequence analysis indicated that TRX might interact with the WSSV030 (VP362) and WSSV454 (thymidine kinase–thymidylate kinase, TK-TMK) of WSSV. In this study, TRX, VP362 and TK-TMK were expressed and the interaction of TRX with VP362 or TK-TMK was investigated. Furthermore, how TRX affect the process of WSSV infection and the gene transcription of inhibitor of nuclear factor kappa-B kinase (IKK), a p38 mitogen-activated protein kinase (LvP38) and signal transducer and activator of transcription (STAT) in the hemocytes and hepatopancreas was explored. Far-western blot and enzyme-linked immuno assay (ELISA) results showed that TRX interacted with VP362 and TK-TMK. The mRNA expressions of IKK, LvP38 and STAT were significantly affected by the over-presence of TRX of Litopenaeus vannamei . Neutralization experiment in vivo indicated that TRX induced the transcription expression of VP28 and increased the viral copy numbers in the early stage of WSSV infection and it may attribute to the death of shrimps infected by WSSV. [ABSTRACT FROM AUTHOR]

The interaction between viral structural proteins and host plays key functions in viral infection. In previous studies, most research have been undertaken to explore the interaction of envelope structural proteins with host molecules. However, how the nucleocapsid proteins of WSSV interacted with host molecules remained largely unknown. In this study, the interaction of nucleocapsid protein VP51 and ribosomal protein L7 of Litopenaeus vannamei (LvRPL7) was reported. Furthermore, the mRNA transcriptional response of LvRPL7 to WSSV was investigated. The results showed that LvRPL7 was widely distributed in all analyzed tissues of L. vannamei . The high expression levels of LvRPL7 were found in the tissues of muscle and gills. The temporal expression of LvRPL7 in WSSV-challenged shrimp showed that LvRPL7 was up-regulated (P < 0.5) in the muscle at 8 h and 24 h post WSSV challenge and then restored to the normal levels. But the LvRPL7 expression was up-regulated (P < 0.5) in the hepatopancreas at 8 h post WSSV challenge and down-regulated at 12 h and 24 h post WSSV challenge. Indirect immunofluorescence assay indicated that LvRPL7 was mainly located on the surface and cytoplasm of hemocytes. Far-Western blotting showed that VP51 bound with LvRPL7. Moreover, ELISA results appeared that LvRPL7 interacted with VP51 in concentration dependent manner. Neutralization assay in vivo showed that anti-LvRPL7 antibody significantly delayed WSSV infection. Our results reveal that LvRPL7 was involved in WSSV infection. [ABSTRACT FROM AUTHOR]