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The relationship between inbreeding and traits of disease resistance in shrimp has not been studied comprehensively. To explore the effect of inbreeding on white spot syndrome virus (WSSV) resistance in Fenneropenaeus chinensis, we established F. chinensis “Huanghai No. 5” populations with different inbreeding coefficients. We infected F. chinensis individuals with WSSV to compare WSSV-resistance between five inbred groups and a control group. Survival time, survival rate, distribution of deaths, and cumulative mortality rate were analyzed. A mixed linear model was established based on the acquired data. The viral load in muscle tissue of F. chinensis of 12 families from the five inbred groups and the control group was determined at different time points via real-time PCR. The average survival and longest survival time of the inbred groups were lower than those of the control group, and the coefficient of variation was universally greater than that of the control group. The least squares means of survival time of the five inbred groups (F0.1325, F0.25, F0.3125, F0.375, F0.5) were 118.96 115.14, 124.58, 123.97, and 101.34 h, respectively, which were 10.28%, 13.16%, 6.04%, 6.5%, and 23.57% lower than that of the control group. Further, when the inbreeding coefficient increased by 10%, WSSV infection survival time was changed by − 7.76%, − 5.26%, − 1.93%, − 1.73%, and − 4.71% for the five inbred groups, respectively. Thus, the results indicated that inbreeding enhanced the susceptibility of F. chinensis to WSSV infection, and the resistance of F. chinensis to WSSV declined as the inbreeding coefficient values increased, consequently, resulting in greater population dispersion, intensified differentiation, and instability of resistant phenotypes. In conclusion, we elucidated the effect of inbreeding on F. chinensis resistance to WSSV infection and established a theoretical basis to conduct further research in the future.

Cyclophilin A (CypA), a key member of the immunophilin family, is the most abundantly expressed one among the 16 identified cyclophilins. Besides acting as an intracellular receptor for cyclosporine A, CypA plays a vital role in various pathological responses such as inflammation and microbial infections. In the present study, the full-length cDNA of Fenneropenaeus chinensis CypA (FcCypA) was cloned by RACE technique. The complete sequence of FcCypA cDNA contained a 5' untranslated region (UTR) of 33 bp, a 3’ UTR of 341 bp with a polyA tail, and an open reading frame (ORF) of 495 bp encoding a polypeptide of 164 amino acids with the predicted molecular weight of 17.70 kDa. The amino acid sequence of CypA has a typical peptidyl prolyl cis-trans isomerase family tag sequence (YKGSTFHRVIPNFMCQGG) as those of other species. The mRNA transcripts of FcCypA were constitutively expressed in all the tested tissues, including eyestalk, gill, gonad, heart, hemocytes, hepatopancreas, intestine, muscle, nerve and stomach, with the highest expression level in hepatopancreas. The mRNA expression profiles of FcCypA in hemocytes and hepatopancreas could be significantly induced by the stimulation of Vibrio anguillarum suspension and white spot syndrome virus (WSSV) stock, which verifies that CypA has an effect on viral and bacterial infection in shrimps. These results indicate that CypA may be involved in the innate immunity, biological immune response and physiological stress response of Chinese shrimps.

Protein phosphorylation and dephosphorylation are the most common and important regulatory mechanisms in signal transduction, which play a vital role in immune defense response. Our previous study has found the level of tyrosine phosphorylation was significantly changed in the hemocytes of Fenneropenaeus chinensis upon white spot syndrome virus (WSSV) infection. In order to explore the relationship between protein phosphorylation and WSSV infection, the quantitative phosphoproteomics was employed to identify differential phosphorylated proteins in hemocytes of F. chinensis before and after WSSV infection, and elucidate the role of key differential phosphorylated proteins in WSSV infection process. The results showed that a total of 147 differential phosphorylated proteins were identified in the hemocytes, including 64 phosphorylated proteins and 83 dephosphorylated proteins, which were mostly enriched in pyruvate metabolism, TCA cycle, glycolysis, and ribosomal biosynthesis. Functional analysis of differential phosphorylated proteins showed that they were involved in cell apoptosis, cell phagocytosis, cell metabolism and antiviral infection. A total of 236 differential phosphorylation sites were found, including 91 modified sites in the phosphorylation proteins and 145 modified sites in the dephosphorylation proteins. Motif analysis showed that these phosphorylation sites could activate mitogen-activated protein kinase, P70 S6 kinase and other kinases in hemocytes. Moveover, the phosphorylation levels of eukaryotic protein initiation factor 4E binding proteins and histone H3 were further determined by ELISA and Western blotting, which both exhibited a significant increase post WSSV infection and reach their peak levels at 6 and 12 h, respectively. Moreover, we found that lactate, a metabolite closely related to pyruvate metabolism, TCA cycle and glycolysis, was significantly increased in the hemocytes after WSSV infection. This study revealed the protein phosphorylation response in hemocytes of F. chinensis to WSSV infection, which help to clarify the response characteristics and virus resistance mechanism of hemocytes in F. chinensis , and also facilitate further understanding of the interaction between WSSV and shrimp hemocytes. • The phosphorylation response of hemocytes was determined at the early WSSV infection stage. • 147 differential phosphorylated proteins were identified in the WSSV-infected hemocytes. • Differential phosphoproteins were significantly enriched in energy metabolism. • The lactate concentration in hemocytes was significantly increased after WSSV infection. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) is one of the most lethal viruses in shrimp aquaculture. Compared with other shrimp species, the Chinese shrimp (Fenneropenaeus chinensis) is more susceptible to WSSV. The mortality of WSSV-infected F. chinensis can reach 100% within a week. No effective solution currently exists to solve the WSSV problem in F. chinensis aquaculture. After years of research, we found that individual F. chinensis from the same family can carry different viral load at the same time post-WSSV infection. To better understand the anti-WSSV mechanism of F. chinensis, we analysed the transcriptomic data from F. chinensis with high and low WSSV load at the same time post-WSSV infection and from healthy F. chinensis, in a WSSV-resistant group and a WSSV-susceptible group, respectively. We identified more differentially expressed genes in F. chinensis with high WSSV load than in those with low WSSV load at the same time post-WSSV infection. Many differentially expressed genes were enriched in Gene Ontology terms related to binding function and the extracellular matrix-receptor interaction pathway, which might play important roles in the anti-WSSV processes among F. chinensis.

Cyclophilin A (CypA), a key member of the immunophilin family, is the most abundantly expressed one among the 16 identified cyclophilins. Besides acting as an intracellular receptor for cyclosporine A, CypA plays a vital role in various pathological responses such as inflammation and microbial infections. In the present study, the full-length cDNA of Fenneropenaeus chinensis CypA (FcCypA) was cloned by RACE technique. The complete sequence of FcCypA cDNA contained a 5' untranslated region (UTR) of 33 bp, a 3' UTR of 341 bp with a polyA tail, and an open reading frame (ORF) of 495 bp encoding a polypeptide of 164 amino acids with the predicted molecular weight of 17.70 kDa. The amino acid sequence of CypA has a typical peptidyl prolyl cis-trans isomerase family tag sequence (YKGSTFHRVIPNFMCQGG) as those of other species. The mRNA transcripts of FcCypA were constitutively expressed in all the tested tissues, including eyestalk, gill, gonad, heart, hemocytes, hepatopancreas, intestine, muscle, nerve and stomach, with the highest expression level in hepatopancreas. The mRNA expression profiles of FcCypA in hemocytes and hepatopancreas could be significantly induced by the stimulation of Vibrio anguillarum suspension and white spot syndrome virus (WSSV) stock, which verifies that CypA has an effect on viral and bacterial infection in shrimps. These results indicate that CypA may be involved in the innate immunity, biological immune response and physiological stress response of Chinese shrimps. [ABSTRACT FROM AUTHOR]

C-type lectins (CTLs) are glycan-binding pattern recognition receptors (PRRs) that can bind to carbohydrates on pathogen surfaces, triggering immune responses in shrimp innate immunity. In this study, a unique Ca2+-inhibited CTL named Fc Lec was identified and characterized in Chinese shrimp Fenneropenaeus chinensis. The full-length cDNA sequence of Fc Lec was 976 bp (GenBank accession number KU361826), with a 615 bp open reading frame (ORF) encoding 204 amino acids. Fc Lec possesses a C-type lectin-like domain (CTLD) containing four conserved cysteines (Cys105, Cys174, Cys192, and Cys200) and two sugar-binding site structures (QPD and LNP). The tertiary structure of Fc Lec deduced revealed three α-helices and eight β-pleated sheets. The mRNA expression levels of Fc Lec in hemocytes and the hepatopancreas were markedly elevated after stimulation with Vibrio anguillarum and white spot syndrome virus (WSSV). The recombinant Fc Lec protein exhibited Ca2+-independent hemagglutination and bacterial agglutination, but these activities were observed only in the presence of EDTA to chelate metal ions. These findings suggest that Fc Lec plays important and functionally distinct roles in the shrimp's innate immune response to bacteria and viruses, enriching the current understanding of the relationship between CTL activity and Ca2+ in invertebrates. [Display omitted] • A novel CTL, Fc Lec, were identified from F. chinensis. • Fc Lec plays distinct and significant roles in the innate immune system's reaction to microbial assaults. • Fc Lec exhibits Ca2+-independent and even Ca2+-inhibited activity. [ABSTRACT FROM AUTHOR]

The apoptosis of hemocytes plays an essential function in shrimp immune defense against pathogen invasions. In order to further elucidate the differential apoptotic responses of the granulocytes and the hyalinocytes in Fenneropenaeus chinensis post WSSV infection, the characteristics of apoptotic dynamics and viral proliferation in total hemocytes and hemocyte subpopulations were respectively investigated in the present work. The results showed that the apoptotic rate of hemocytes changed significantly, and the apoptosis-related genes also showed significantly differential expression responses during WSSV infection. Interestingly, we found that the apoptotic rate of virus-negative hemocytes was significantly higher than that of virus-positive hemocytes in the early stage of WSSV infection, while it was significantly lower than that of virus-positive cells in the middle and late infection stages. The difference of apoptosis between virus-positive and virus-negative hemocytes seems to be an important way for the WSSV to destroy the host’s immune system and facilitate the virus spread at different infection stages. It was further found that the apoptosis rate of granulocytes was always significantly higher than that of hyalinocytes during WSSV infection, indicating that granulocytes have a stronger apoptotic response to WSSV infection. Moreover, a higher viral load was detected in granulocytes, and the density of granulocytes decreased more rapidly post WSSV infection, indicating that the granulocytes are more susceptible and vulnerable to WSSV infection compared with the hyalinocytes. These results collectively demonstrated that the apoptotic response in shrimp hemocytes was significantly influenced by the WSSV infection, and the differential apoptotic response of granulocytes and hyalinocytes to WSSV indicated the differences of antiviral mechanisms between the two hemocyte subpopulations.

The apoptosis of hemocytes plays an essential function in shrimp immune defense against pathogen invasions. In order to further elucidate the differential apoptotic responses of the granulocytes and the hyalinocytes in Fenneropenaeus chinensis post WSSV infection, the characteristics of apoptotic dynamics and viral proliferation in total hemocytes and hemocyte subpopulations were respectively investigated in the present work. The results showed that the apoptotic rate of hemocytes changed significantly, and the apoptosis-related genes also showed significantly differential expression responses during WSSV infection. Interestingly, we found that the apoptotic rate of virus-negative hemocytes was significantly higher than that of virus-positive hemocytes in the early stage of WSSV infection, while it was significantly lower than that of virus-positive cells in the middle and late infection stages. The difference of apoptosis between virus-positive and virus-negative hemocytes seems to be an important way for the WSSV to destroy the host's immune system and facilitate the virus spread at different infection stages. It was further found that the apoptosis rate of granulocytes was always significantly higher than that of hyalinocytes during WSSV infection, indicating that granulocytes have a stronger apoptotic response to WSSV infection. Moreover, a higher viral load was detected in granulocytes, and the density of granulocytes decreased more rapidly post WSSV infection, indicating that the granulocytes are more susceptible and vulnerable to WSSV infection compared with the hyalinocytes. These results collectively demonstrated that the apoptotic response in shrimp hemocytes was significantly influenced by the WSSV infection, and the differential apoptotic response of granulocytes and hyalinocytes to WSSV indicated the differences of antiviral mechanisms between the two hemocyte subpopulations. [ABSTRACT FROM AUTHOR]

In our previous work, prohibitin1 (PHB1) was identified to be only expressed in granulocytes of Fenneropenaeus chinensis. In order to elucidate the potential immunological properties of prohibitins in hemocyte subpopulations, in this paper, the full-length cDNAs of PHB1 and PHB2 were firstly cloned from F. chinensis using rapid amplification of cDNA ends approach, and they were designated Fc PHB1 and Fc PHB2, respectively. Based on the sequence analysis and multiple sequence alignment, Fc PHB1 and Fc PHB2 were members of SPFH protein family. By quantitative real-time RT-PCR, the higher mRNA transcription levels of Fc PHB1 and Fc PHB2 were detected in intestine and hemocytes of F. chinensis , and these two genes in hemocytes were significantly up-regulated upon WSSV infection. The Fc PHB1 and Fc PHB2 were recombinantly expressed in Escherichia coli BL21 (DE3), and employed as immunogens to produce the polyclonal antibodies (PAbs) in rabbits. Indirect immunofluorescence assay (IFA) revealed that the Fc PHB1 and Fc PHB2 were located both in the cytoplasm and nuclei of hemocytes, which could also be specifically recognized by the PAbs against Fc PHB1 or Fc PHB2 in Western blot. Interestingly, it was found that Fc PHB1 and Fc PHB2 were only expressed in the granulocytes of heathy shrimp and highly expressed in the WSSV-infected granulocytes, however only weak expressions of Fc PHB1 and Fc PHB2 were observed in the hyalinocytes of WSSV-infected shrimp. Meanwhile, silencing of Fc PHB1 and Fc PHB2 genes were performed by small interfering RNA, and the results showed that the WSSV copies in hemocytes were increased by knockdown of either Fc PHB1 or Fc PHB2, and the cumulative mortalities of shrimp in the silenced groups were also markedly increased. These results demonstrated that Fc PHB1 and Fc PHB2 played important roles in anti-WSSV infection, and their differential expression characteristics in hemocyte subpopulations provided a further understanding of the immune functions of granulocytes and hyalinocytes. • The cDNA sequences of PHB1 and PHB2 of Fenneropenaeus chinensis were cloned and characterized. • Fc PHB1 and Fc PHB2 were significantly up-regulated post WSSV infection. • Fc PHB1 and Fc PHB2 play important roles in inhibiting WSSV infection. • Fc PHB1 and Fc PHB2 were differentially expressed in granulocytes and hyalinocytes. [ABSTRACT FROM AUTHOR]

Abstract Raf is a member in the Ras/Raf/MAPKK/MAPK signaling transduction pathway. To obtain a better understanding of Raf in the interaction between the Chinese shrimp Fenneropenaeus chinensis and white spot syndrome virus (WSSV), the sequence of cDNA of Raf from F. chinensis (FcRaf) was obtained. The FcRaf gene contained a 2421 bp open reading frame (ORF). The FcRaf shared most characteristic of Raf protein, such as the Raf-like Ras-binding domain (RBD), phorbol esters/diacylglycerol binding domain (C1 domain), and catalytic domain of the serine/threonine kinases, Raf (STKc_Raf). The sequence of functional domains of Raf protein was relatively conserved. The FcRaf mRNA was detected in the tissues of gill, muscle, and hepatopancreas from normal F. chinensis. The mRNA abundance level of FcRaf in the gill was the highest, which was 2.7-fold the level in the hepatopancreas. The expression level of FcRaf was significantly (P < 0.05) up-regulated in the tissues of gill, muscle, and hepatopancreas post WSSV-infection, which suggested that FcRaf might be involved in the interaction between F. chinensis and WSSV. Two SNP loci were identified in the ORF, one of which was a C-T mis-sense mutation, where an Ala was replaced by a Val, and induced the predicted protein secondary structure change. Considering the relatively low MAF (0.07), whether this mis-sense mutation was a detrimental mutation needs further investigation. Highlights • A cDNA encoding Raf from Fenneropenaeus chinensis (FcRaf) was cloned and sequenced for the first time. • The sequence of functional domains of FcRaf protein was relatively conserved. • The FcRaf mRNA abundance level in tissues fluctuated post WSSV challenge. • Two SNPs were identified in the FcRaf ORF and one of which was a mis-sense mutation. [ABSTRACT FROM AUTHOR]

In our previous study, the differentially expressed proteins have been identified by proteomic analysis in total haemocytes of shrimp ( Fenneropenaeus chinensis ) after white spot syndrome virus (WSSV) infection. To further investigate the differential response of haemocyte subpopulations to WSSV infection, granulocytes and hyalinocytes were separated from healthy and WSSV-infected shrimp by immunomagnetic bead (IMB) method, respectively. Then two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) were used to analyze the differentially expressed proteins in haemocyte subpopulations between healthy and WSSV-infected shrimp. The results of flow cytometry (FCM) showed that about 98% of granulocytes and about 96% of hyalinocytes in purity were obtained. Quantitative intensity analysis revealed that 26 protein spots in granulocytes and 24 spots in hyalinocytes were significantly changed post WSSV infection. Among them, 24 proteins in granulocytes and 23 proteins in hyalinocytes were identified by MS analysis, which could be divided into eight categories according to Gene Ontology. The identification of prophenoloxidase (proPO), proPO 2 and peroxiredoxin in WSSV-infected granulocytes was consistent with the facts that the proPO-activating system and peroxiredoxin were mainly existed in granulocytes. The phagocytosis of hyalinocytes seemed to be enhanced during the infection, because several proteins that involved in phagocytosis, including clathrin heavy chain, ADP ribosylation factor 4 and Alpha2 macroglobulin were up-regulated in hyalinocytes upon WSSV infection. Our results also reflected the vital biological significance of calcium ion binding proteins in granulocytes and ATPase/GTPase in hyalinocytes during WSSV infection. The data in this study verified the roles of granulocytes and hyalinocytes involved in WSSV infection, and differentially expressed proteins identified in granulocytes and hyalinocytes had a close correlation with their function characteristics. [ABSTRACT FROM AUTHOR]

To elucidate the molecular response of shrimp hepatopancreas to white spot syndrome virus (WSSV) infection, microarray was applied to investigate the differentially expressed genes in the hepatopancreas of 'Huanghai No. 2' ( Fenneropenaeus chinensis). A total of 59137 unigenes were designed onto a custom-made 60K Agilent chip. After infection, the gene expression profiles in the hepatopancreas of the shrimp with a lower viral load at early (48-96 h), peak (168-192 h) and late (264-288 h) infection phases were analyzed. Of 18704 differentially expressed genes, 6412 were annotated. In total, 5453 differentially expressed genes (1916 annotated) expressed at all three phases, and most of the annotated were either up- or down-regulated continuously. These genes function diversely in, for example, immune response, cytoskeletal system, signal transduction, stress resistance, protein synthesis and processing, metabolism among others. Some of the immune-related genes, including antilipopolysaccharide factor, Kazal-type proteinase inhibitor, C-type lectin and serine protease encoding genes, were up-regulated after WSSV infection. These genes have been reported to be involved in the anti-WSSV responses. The expression of genes related to the cytoskeletal system, including β-actin and myosin but without tubulin genes, were down-regulated after WSSV infection. Astakine was found for the first time in the WSSV-infected F. chinensis. To further confirm the expression of differentially expressed genes, quantitative real-time PCR was performed to test the expression of eight randomly selected genes and verified the reliability and accuracy of the microarray expression analysis. The data will provide valuable information to understanding the immune mechanism of shrimp's response to WSSV. [ABSTRACT FROM AUTHOR]

MicroRNA (miRNA) is a class of small noncoding RNA, which is involved in the post-transcriptional regulation in all metazoan eukaryotes. MiRNAs might play an important role in the host response to virus infection. However, miRNAs in the aquatic crustacean species were not extensively investigated. To obtain a better understanding of the response of Chinese shrimp Fenneropenaeus chinensis to white spot syndrome virus (WSSV) infection, the sequence and expression profile of miRNAs in the hepatopancreas of WSSV-infected F . chinensis were obtained by the high-throughput Illumina HiSeq 2500 deep sequencing technique. A total number of 129 known miRNAs and 44 putative novel miRNAs were identified from the deep sequencing data. The peak size of miRNAs was 22 nt (37.0%). 25 miRNAs were significantly ( P < 0.05) differentially expressed post WSSV infection. Six of the differentially expressed miRNAs were randomly selected for further verification by the real-time RT-PCR technique. The results showed that there was a consistency between the deep sequencing and real-time RT-PCR assay. The target genes of differentially expressed miRNAs were predicted. Each miRNA had 4 target genes on average. The results suggested that some specific miRNAs might be involved in the response of F . chinensis to WSSV infection, and further provided basic information for the investigation of specific miRNAs in F . chinensis . [ABSTRACT FROM AUTHOR]

Our previous study demonstrated that an integrin β subunit of Chinese shrimp (Fenneropenaeus chinensis) (FcβInt) plays an important role in white spot syndrome virus (WSSV) infection. In the present work, in order to further elucidate the potential role of FcβInt in WSSV infection, the recombinant extracellular domain of β integringene of F. Chinensis (rFcβInt-ER) was expressed in Escherichia coli BL21 (DE3), and the eukaryotic expression plasmid PcDNA3.1-FcβInt-ER (PFcβInt-ER) was also constructed. Far-western blotting was performed to determine the binding specificity of rFcβInt-ER to WSSV envelope proteins, and results showed that rFcβInt-ER was able to specifically interact with rVP31, rVP37, rVP110 and rVP187. Moreover, the blocking effects of mouse anti-rFcβint-ER antibodies were both detected in vivo and in vitro. The ELISA and Dot-blotting in vitro assays both showed that mouse anti-rFcβInt-ER antibodies could partially block the binding of WSSV to the hemocyte membrane of F. chinensis. In the in vivo assays, the mortality of shrimp injected with WSSV mixed with anti-rFcβInt-ER antibodies was delayed, and was lower than in the control group. While the shrimp were intramuscularly injected with PFcβInt-ER, transcripts of PFcβInt-ER could be detected in different shrimp tissues within 7 days, and the mortality of shrimp injected with PFcβInt-ER was also delayed and lower compared with the control group post WSSV challenge. Furthermore, gene silencing technology was also used to verify the effect of FcβInt in WSSV infection, and results showed that the expression levels of the WSSV immediate early gene iel, early gene wsv477, and late gene VP28 and the mortality of F. Chinensis were all significantly decreased in the FcβInt knock-down hemocyctes compared to the control group. Taken together, these results suggest that FcβInt plays important roles in WSSV infection. [ABSTRACT FROM AUTHOR]

Mitogen-activated kinase kinase (MAPKK) is an important gene involved in the host-virus interaction process. To obtain a better understanding of MAPKK in the interaction process between the Chinese shrimp Fenneropenaeus chinensis and white spot syndrome virus (WSSV), we cloned the sequence of an MAPKK cDNA from F . chinensis ( FcMAPKK ) and investigated the effect of FcMAPKK on WSSV infection. The results showed that the FcMAPKK gene contained a 1227 bp open reading frame (ORF), which encoded a highly conserved protein with a serine/threonine protein kinase catalytic (S_TKc) domain. The deduced amino acid sequence of FcMAPKK shared identities between 11.9 and 92.6% with MAPKKs from vertebrate, invertebrate, plant and fungus species. The FcMAPKK was expressed in all the examined tissues in the normal F . chinensis . FcMAPKK expression level was highest in the hepatopancreas where it was approximately 2.6-fold the expression level in the gill, and lowest in the muscle where it was approximately 0.3-fold the expression level in the hepatopancreas. The FcMAPKK expression levels in the muscle, gill, and hepatopancreas were all changed post WSSV challenge. The FcMAPKK expression was significantly ( P < 0.01) up-regulated in the muscle of F . chinensis at 48 h post WSSV infection. The WSSV began to replicate quickly in the normal F . chinensis at 48 h post infection, while the WSSV replication in the U0126-treated F . chinensis could be significantly ( P < 0.05) inhibited. The results suggested that FcMAPKK might be involved in the WSSV infection process, and hijacking of FcMAPKK might be required for WSSV replication in F . chinensis . [ABSTRACT FROM AUTHOR]

As the direct executors of biological function, the expression level of proteins will reveal the molecular mechanisms regulating WSSV acute infection more directly. In the present study, the iTRAQ approach was applied to identifying differentially expressed proteins in Chinese shrimp during WSSV latent infection and acute infection. A total of 4051 unique peptides corresponding to 1286 proteins were identified. 118 unique proteins showed differential up-regulation and 122 proteins were down-regulated in shrimp during WSSV acute infection compared with those in WSSV latent infection stage. A number of proteins related to actin-myosin cytoskeleton process, including myosin, actin, tubulin, clathrin, and tropomyosin were found up-regulated in shrimp at WSSV AI stage, indicating that the phagocytosis process was involved in WSSV AI stage. The apoptosis process in shrimp during WSSV AI seemed to be inhibited because some proteins suppressive on apoptosis were up-regulated, such as ALG-2 interacting protein x, Hsp90, 14-3-3-like protein, peroxiredoxin 5, peroxiredoxin 6 and adenine nucleotide translocase 2. Association analysis between the proteomic data and the previous transcriptome data was performed. Quantitative real-time PCR and western blot were carried out to verify the reliability of the proteomics data. The present study provided a comprehensive view of molecular mechanisms regulating WSSV acute infection at the protein level. [ABSTRACT FROM AUTHOR]

Haemocyanin (Hc) is frequently reported to vary significantly by physiological status and environmental stress in Crustaceans. In this paper, the shrimp Fenneropenaeus chinensis was infected with different concentrations of white spot syndrome virus (WSSV) and Vibrio harveyi . Then, the variation of Hc and total protein content of the haemolymph (TPCH) were investigated using the established double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) and Coomassie brilliant blue method, respectively. The results showed that the Hc content peaked at 12 h post-infection (PI) in the 10 −2 , 10 −4 and 10 −6 viral supernatant (VS) groups, and the maximum was 93.03 ± 2.55 mg ml −1 , 77.57 ± 6.02 mg ml −1 and 70.25 ± 3.96 mg ml −1 , respectively. TPCH reached the maximum of 108.18 ± 1.36 mg ml −1 and 103.49 ± 1.33 mg ml −1 at 12 h PI in the 10 −2 and 10 −4 VS groups, respectively. The maximum was 96.94 ± 1.06 mg ml −1 at 24 h PI in the 10 −6 VS group. In the V. harveyi infection groups, the Hc content reached a maximum of 87.97 ± 4.39 mg ml −1 at 36 h PI in the 10 6 CFU ml −1 group, 73.74 ± 4.38 mg ml −1 and 72.47 ± 2.09 mg ml −1 at 12 h PI in the 10 7 and 10 8 CFU ml −1 groups, respectively. TPCH reached a maximum of 111.16 ± 0.86 mg ml −1 at 36 h PI in the 10 6 CFU ml −1 group, 100.41 ± 0.51 mg ml −1 and 101.94 ± 0.47 mg ml −1 at 12 h PI in the 10 7 and 10 8 CFU ml −1 groups, respectively. These data showed that both Hc content and TPCH varied as the same extent after infection. The up-regulation of the Hc content at 6–36 h PI might be a reference threshold for shrimp infection. [ABSTRACT FROM AUTHOR]

In this study, we cloned and sequenced genomic sequences from a Fenneropenaeus chinensis transcriptional repressor gene, FcTR. The FcTR gene is 2,671 bp in length and has four exons and three introns. The 873 bp promoter contains several transcription factor binding sites, including a TATA box and a cyclic AMP-responsive element. Promoter deletion analysis using a luciferase reporter gene identified regulatory elements. Challenge with white spot syndrome virus increased expression from the promoter-deletion constructs. These results suggest that FcTR might play an important role in the shrimp immune response. [ABSTRACT FROM AUTHOR]

To investigate the role of cytoplasmic dynein in white spot syndrome virus (WSSV) infection, the full-length cDNA of cytoplasmic dynein intermediate chain (FcDYNCI) was cloned in Fenneropenaeus chinensis, which consists of 2582 bp and encodes a polypeptide of 660 amino acids. Sequence analysis and multiple sequence alignment displayed that FcDYNCI was a member of cytoplasmic dynein 1 family. The FcDYNCI mRNA was most highly expressed in hemocytes, which was significantly up-regulated post WSSV infection. At 12 h post infection (hpi), confocal microscopic observation showed that WSSV could be co-localized with cytoplasmic dynein in hemocytes. After silencing by specific FcDYNCI dsRNA, the FcDYNCI mRNA level and the protein amount of FcDYNCI in hemocytes both exhibited a significant reduction, and the expression levels of three WSSV genes ie1, wsv477 and vp28 all exhibited the greatest decreases at 24 hpi. These results suggested that cytoplasmic dynein was involved in WSSV infection. [ABSTRACT FROM AUTHOR]

The change in the level of protein tyrosine phosphorylation in hemocytes of Fenneropenaeus chinensis (Osbeck, 1765) (cf., Pérez Farfante and Kensley, 1997) was detected by phospho-specific flow cytometry during white spot syndrome virus (WSSV) infection. Post WSSV infection, the hemocytes could be classified into two subsets with up- or down-regulated tyrosine phosphorylation level, whereas the geometric mean level of tyrosine phosphorylation in total hemocytes was significantly increased and exhibited two peaks at 1 and 12 hour post infection. Confocal microscopic observation revealed that the tyrosine phosphorylated proteins were localized in nucleus as well as cytoplasm, and five tyrosine phosphorylated proteins were detected in hemocytes by western blotting using phosphor-tyrosine-specific antibody, which were identified to be histone H2A, histone H3, histone H4, alpha-2-macroglobulin, and heat shock protein 70 by mass spectrometry. Moreover, the expression levels of h2a, h3, and h4 were examined to be significantly up-regulated post WSSV infection by quantitative real-time RT-PCR. These results indicated that protein tyrosine phosphorylation in shrimp hemocytes had a close correlation with WSSV infection. [ABSTRACT FROM AUTHOR]

Abstract: Inbreeding effects on growth, survival and anti-WSSV (White Spot Syndrome Virus) traits were studied in experimental full-sibling inbred populations of Chinese shrimp Fenneropenaeus chinensis at three levels of inbreeding coefficient (F =0.25, F =0.375, F =0.50) from a Chinese shrimp selection program. The body weight of the control group (F ≈0.00) was significantly different from those of the three levels of inbreeding groups at three postlarval stages (PL80, PL100 and PL140). At PL140, an increasing inbreeding depression of growth was observed with increasing inbreeding coefficient. The inbreeding depression was found to be −10.4% at F =0.25, −16.61% at F =0.375 and −23.68% at F =0.50. There was also a tendency for inbreeding depression for body weight to increase with age. The estimated coefficient of body weight of PL140 were −4.16%, −4.43% and −4.74% per 10% increase of inbreeding coefficient of F =0.25, F =0.375, F =0.50, respectively. During growout, inbreeding depression of survival ranged from −0.98% to −12.44%, although the effects were not significant. Over all levels of inbreeding the average inbreeding depression was found to be −5.95% for survival of PL80, −5.51% for PL100 and −6.71% for PL140. The estimated average inbreeding depression coefficient of survival ranged from −1.27% to −1.77% per 10% increase of inbreeding coefficient of F, lower than the estimate obtained for growth. The effects of inbreeding on survival time after challenge with White Spot Syndrome Virus (WSSV) were not significant, as there was no significant difference in survivorship among the control and the three levels of inbreeding coefficient groups. The inbreeding depression of the three levels ranged from −0.68% to −2.22%, and the estimated inbreeding depression coefficient of survival time ranged from −0.27% to −0.44% per 10% increase of inbreeding coefficient of F. This study demonstrates that inbreeding has a negative effect on the economic traits, especially on growth, thus highlighting the need to maximize the genetic diversity in selective breeding programs. [Copyright &y& Elsevier]

Abstract: White spot syndrome virus (WSSV) is the most severe viral pathogen to the shrimp culture industry worldwide. The temporal and spatial dynamic changes of WSSV in Chinese shrimp Fenneropenaeus chinensis maintained at 22±1°C during infection via injection were studied through the quantitative real-time PCR method. The pleopods were selected for virus quantification at 0, 6, 12, 18, 24, 27, 30, 33, 36, 39, 42, 45 and 48hours post-injection (hpi). Besides the pleopod, different tissues including the hepatopancreas, nerve, heart, eyestalk, muscle, lymphoid organ, gut, stomach, gill and skin were also selected for viral load analysis at 0, 12, 27 and 30hpi as well as the moribund stage after 40hpi. The curve of viral load change in vivo assumed a very similar shape with the typical viral one-step growth curve. The infection process was classified into three stages: the light infection stage (0 to 18hpi) when the viral load in the pleopod was at the level of no more than 103/ng DNA and no mortality appeared; the moderate infection stage (18 to 45hpi), corresponding to the logarithmic phase of WSSV replication, when the viral load in the pleopod ranged from 103 to 105/ng DNA and a low mortality rate was observed; and the heavy infection stage when WSSV propagation went into the plateau phage and massive mortality happened. A turning point from chronic infection to acute infection was suggested from 27 to 30hpi when the viral load in most tissues increased substantially. The progress rate of WSSV in different tissues during the infection was different and the most favorite replication tissue of WSSV in early infection is the stomach, followed by the gill. The heaviest infected tissues are the skin, stomach and gill, explaining the symptoms of skin color changes, reduction of food consumption and gathering at the water surface due to dyspnea. The hepatopancreas, muscle and nerve were not the main replication sites in advanced infection. Also, the expression profiles of two anti-virus genes FcALF and FcAV were analyzed. This study might provide important data to study the virus infection mechanism. [Copyright &y& Elsevier]

Abstract: White spot syndrome virus (WSSV) caused a great economic loss in shrimp aquaculture. Although great efforts have been undertaken to characterize the virus disease during the last two decades, there are still lack of effective methods to prevent or cure it. In this study, we investigated the transcriptional expression profiles of 18 key immune-related genes in the Chinese shrimp Fenneropenaeus chinensis which was severely infected by WSSV. We found that the expression levels of 6 genes including chymotrypsin-like serine proteinase (CH-SPase), heat shock protein 70 cognate (HSP70), penaeidin (PEN), peroxinectin (PO), proliferating cell nuclear antigen (PCNA) and argonaute (AGO) changed significantly, while the expression of the other 12 genes had no significant changes compared to the control group. Among the 6 screened genes, CH-SPase showed significantly up-regulation, while the other 5 ones were significantly down-regulated. Knockdown of the expression of CH-SPase in WSSV-infected Chinese shrimp reduced the copy number of WSSV and delayed cumulative mortalities, suggesting that CH-SPase is important for WSSV infection. This study will be helpful to control the disease in shrimp caused by WSSV. [Copyright &y& Elsevier]

Abstract: An integrin β subunit (FcβInt) cDNA was cloned from hemocytes of Fenneropenaeus chinensis by rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA of FcβInt consists of 2853bp and encodes a polypeptide of 783 amino acids with a predicted isoelectric point of 5.09. The deduced amino acid sequence of FcβInt possessed the classical domains of β integrin, including the βA domain and four epidermal-growth-factor (EGF)-like domains, which shared highest similarity with a β integrin of Pacifastacus leniusculus. The FcβInt mRNA was highly expressed in hemocytes, heart and gill, and moderately in gonad and intestine, whereas low expression level was found in muscle and hepatopancreas. FcβInt mRNA in gill was significantly up-regulated in 24h and then gradually decreased below the control level in response to WSSV challenge. The cDNA fragment encoding the extracellular region of FcβInt (FcβInt-ER) was expressed in Escherichia coli BL21 (DE3), and polyclonal antibodies against recombinant FcβInt-ER (rFcβInt-ER) were produced, which could specifically react to the hemocyte membrane by immunofluorescence assay and recognize a 120kDa protein in the hemocytes by western blotting. By ELISA and dot-blot binding assay, rFcβInt-ER exhibited specific WSSV binding activity. Neutralization assay in vivo further demonstrated that rFcβInt-ER could partially block WSSV infection to shrimp. These results suggested that FcβInt plays an important role in WSSV infection. [Copyright &y& Elsevier]

Abstract: Tetraspanins belong to the transmembrane 4 superfamily (TM4SF), which span the cell membrane 4 times and act as bridges or connectors. Increasing evidences have shown that tetraspanins play important role in virus infection. The large extracellular loop (LEL) of a tetraspanin is considered as a possible target of some virus. Tetraspanins are widely found in invertebrates, but the functional roles of most invertebrate tetraspanins have remained unknown. Recently, a tetraspanin, called FcTetraspanin-3, was cloned from the cDNA library of Chinese shrimp, Fenneropenaeus chinensis. The FcTetraspanin-3 constitutive expression in all examined tissues and the expression of the gene were highly induced in hepatopancreas, lymphoid organ and intestine by white spot syndrome virus (WSSV) challenge. In this study, we expressed and purified the recombinant peptide containing the LEL domain of FcTetraspanin-3, and produced the anti-LEL polyclone antibody. The expression of FcTetraspanin-3 was observed by real-time PCR and Western blot. Also, the localization of FcTetraspanin-3-positive cells in intestine and hepatopancreas were revealed by immunofluorescence. The results of anti-LEL antibody blocking experiments shown that the antibody can significantly reduce the mortality of shrimp challenged by WSSV. Additionally, dsRNA interference was utilized to examine the functional role of FcTetraspanin-3 in response to WSSV infection, and a sensible decrease of the viral copy number in the tetraspanin knockdown shrimp. These results suggested the blocking of LEL domain of FcTetraspanin-3 could inhibit the infection of WSSV. FcTetraspanin-3 might play an important role in response to WSSV infection, and the LEL domain of FcTetraspanin-3 might mediate the entry of WSSV. [Copyright &y& Elsevier]

Abstract: White spot syndrome virus (WSSV) infects all shrimp species and is the greatest detriment to shrimp culture. To better understand the mechanism of molecular responses to WSSV infection in Chinese white shrimp Fenneropenaeus chinensis, two dimensional electrophoresis (2-DE) was used. Differentially expressed proteins in the hepatopancreas of control and WSSV-injected Chinese white shrimp between (6, 12 and 24 h post-injection) were screened. Quantitative intensity analysis and mass spectrometry revealed that 54 spots of 47 proteins were significantly up-regulated, including some immune-related proteins, such as Toll receptor precursor, Leu-rich repeat protein, peroxinectin and serine proteinase-like protein. Fourteen spots of 13 proteins, such as heat shock protein, ATP synthase sub-unit beta and thrombospondin, were down-regulated in WSSV-infected shrimps. Protein expression patterns of the infected shrimp were drastically altered by WSSV infection. Some of the altered proteins were further investigated at the mRNA level using semi-quantitative reverse transcript PCR. These data may provide some information about shrimp proteins that participate in the WSSV infection process. [Copyright &y& Elsevier]

Abstract: The protective efficacy of oral administration of VP28 using Bacillus subtilis as vehicles (rVP28-bs) in shrimp, Fenneropenaeus chinensis, upon challenge with white spot syndrome virus (WSSV) was investigated. The calculated relative percent survival (RPS) value of rVP28-bs fed shrimp was 83.3% when challenged on the 14th day post-administration, which is significantly higher (p < 0.001) than that of the group administered recombinant Escherichia coli over-expressing rVP28 (rVP28-e21). After immunization, activities of phenoloxidase (PO), superoxide dismutase (SOD) and inducible nitric oxide synthase (iNOS) in hemolymph were analyzed. It was found that the supplementation of rVP28-bs into shrimp food pellets resulted in the most pronounced increase of iNOS activity (p < 0.001), but had the least influence on activities of PO and SOD. Besides, in the shrimp orally administered with rVP28-bs, the caspase-3 activity was one-fifth that of the control, though the signs of apoptosis (chromatin margination, nuclear fragmentation and apoptotic bodies) could not be observed by transmission electron microscope (TEM). These results suggest that by oral delivery of rVP28-bs, shrimp showed significant resistance to WSSV and an effect on the innate immune system of shrimp. The remarkably enhanced level of iNOS after rVP28-bs administration might be responsible for antiviral defense in shrimp. [Copyright &y& Elsevier]

Abstract: The rotifer Brachionus urceus (Linnaeus, 1758) was experimentally infected with the white spot syndrome virus (WSSV) by the virus–phytoplankton adhesion route in order to assess the possibility of rotifer acting as a vector of WSSV to infect the shrimp Fenneropenaeus chinensis (Osbeck, 1765) larvae at zoea stage III. The nested-PCR test revealed WSSV-positive results in the rotifers exposed to WSSV by the virus–phytoplankton adhesion route. Among 10 replicates in the infection treatment, 40% of F. chinensis larvae became WSSV-positive when fed with WSSV-positive rotifers, whereas all were WSSV-negative for F. chinensis when fed with WSSV-free rotifers. Though the mortality of shrimp larvae in the infection treatment (39.47±15.44%) was higher than that in the control treatment (34.67±15.11%), there was no significant difference in the mortality between them (P > 0.05). These results indicated that the rotifer could serve as a vector in WSSV transmission when ingested. [Copyright &y& Elsevier]

Abstract: Ferritin, the iron storage protein, plays a key role in iron metabolism. A cDNA encoding ferritin (FcFer) was cloned from hepatopancreas of Chinese shrimp, Fenneropenaeus chinensis. The predicted protein contains 170 amino acid residues with a predicted molecular weight (MW) about 19, 422.89Da and theoretical isoelectric point (PI) of 4.73. Amino acid alignment of FcFer revealed 97% homology with Litopenaeus vannamei ferritin. Results of the RT-PCR showed that the expression of FcFer mRNA was up-regulated after shrimp was challenged with either white spot syndrome virus (WSSV) or heavy metal ions (Zn2+ and Cu2+) in the laboratory. A fusion protein containing FcFer was produced and the purified recombinant protein exhibited similar function of iron uptake in vitro. The result of in-gel digestion and identification using LC–ESI–MS showed that two peptide fragments (-DDVALPGFAK- and -LLEDEYLEEQVDSIKK-) of the recombinant protein were identical to the corresponding sequence of L. vannamei ferritin. The recombinant FcFer protein will be proved useful for study on the structure and function of ferritin in F. chinensis. [Copyright &y& Elsevier]

We used microarray technology to study differentially expressed genes in white spot syndrome virus (WSSV)-infected shrimp. A total of 3136 cDNA targets, including 1578 unique genes from a cephalothorax cDNA library and 1536 cDNA clones from reverse and forward suppression subtractive hybridization (SSH) libraries of Fenneropenaeus chinensis, plus 14 negative and 8 blank control clones, were spotted onto a 18 × 18 mm area of NH2-modified glass slides. Gene expression patterns in the cephalothorax of shrimp at 6 h after WSSV injection and moribund shrimp naturally infected by WSSV were analyzed. A total of 105 elements on the arrays showed a similar regulation pattern in artificially infected shrimp and naturally infected moribund shrimp; parts of the results were confirmed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The up-regulated expression of immune-related genes, including heat shock proteins (HSP70 and HSP90), trehalose-phosphate synthase (TPS), ubiquitin C, and so forth, were observed when shrimp were challenged with WSSV. Genes including myosin LC2, ATP synthase A chain, and arginine kinase were found to be down-regulated after WSSV infection. The expression of housekeeping genes such as actin, elongation factor, and tubulin is not stable, and so these genes are not suitable as internal standards for semiquantitative RT-PCR when shrimp are challenged by WSSV. As a substitute, we found that triosephosphate isomerase (TPI) was an ideal candidate of interstandards in this situation. [ABSTRACT FROM AUTHOR]

A number of white spot syndrome virus (WSSV)-binding proteins have been identified previously in the hemocytes of Fenneropenaeus chinensis. In order to further investigate the differential WSSV-binding proteins in hemocyte subpopulations, granular hemocytes and hyalinocytes were sorted from WSSV-infected shrimp by immunomagnetic bead (IMB) method. The results of ELISA and immuno-dot blot assay showed that the WSSV-binding activity of granular hemocytes proteins was much stronger than that of hyalinocytes proteins. And the percentage of WSSV-positive granular hemocytes was significantly higher than that of hyalinocytes post WSSV infection, indicating that granular hemocytes were more susceptible to WSSV infection. Moreover, a total of 9 WSSV-binding proteins were successfully identified in granular hemocytes and hyalinocytes by two-dimensional virus overlay protein binding assay (2D-VOPBA) and MALDI-TOF MS analysis, of which 3 binding proteins (arginine kinase, protease 1 and transglutaminase) existing in both hyalinocytes and granular hemocytes and 6 proteins (F 1 ATP synthase β-chain, hnRNPs, GAPDH, RACK1, β-actin and cellular retinoic acid) detected only in granular hemocytes. Among these identified WSSV-binding proteins, the transglutaminase (TG) was further recombinantly expressed, and the recombinant TG could be bound with WSSV. Subsequently, quantitative real-time PCR analysis showed that differential expression levels of WSSV-binding proteins were observed in granular hemocytes and hyalinocytes. The results of this study revealed that the WSSV-binding proteins were differentially expressed in granular hemocytes and hyalinocytes, which provided a deeper insight into the interaction between WSSV and hemocyte subpopulations. • Granulocytes proteins exhibited higher WSSV-binding activity than that of hyalinocytes. • A total of 9 WSSV-binding proteins were identified in granulocytes and hyalinocytes. • 3 WSSV-binding proteins were identified in both granulocytes and hyalinocytes. • 6 WSSV-binding proteins were detected in only granulocytes. [ABSTRACT FROM AUTHOR]

• FcActRII and FcFSTL were cloned and characterized in Chinese Shrimp. • Two genes were expressed in the early development stages and various tissues. • Expressions of two genes in muscle significantly differed between L and S groups. • FcActRII expression significantly decreased after down-regulating of FcMstn. • FcFSTL expression increased after inhibition of FcMstn expression. Activin receptor (ActR) and follistatin-like (FSTL) genes, which are involved in the Myostatin (Mstn) related TGF-β/Smad signaling pathway, play important roles in regulating the muscle generation, development and growth of muscle in vertebrate. Our previous studies have confirmed that Mstn negatively regulates muscle development and growth in Fenneropenaeus chinensis as that in vertebrate. However, the roles of ActR and FSTL in muscle development and growth in invertebrate remains unclear. In the present study, type II ActR(FcActRII) and FSTL (FcFSTL) genes from F. chinensis were cloned and characterized, and their functions on muscle development and growth were investigated. The full-length cDNAs of FcActRII and FcFSTL were 2366 bp that encoded 572 amino acids and 2474 bp that encoded 717 amino acids, respectively. Sequence analysis revealed that the overall protein sequences of the two genes shared 97% and 96% identities with Penaeus vannamei and 50%-59% and 35%-36% identities with vertebrates, respectively. In the early development stages, muscles firstly appeared in nauplius stage and developed gradually until post larval, and the mRNA expressions of FcActRII increased from gastrula to zoea stage and then decreased from zoea stage to post larval stage while that of FcFSTL was lowest in gastrula stage and increased rapidly in nauplius stage and then expressed stably from nauplius stage to post-larval stage. In the adult shrimp, the two genes were widely distributed in the examined tissues. The FcActRII expression in muscle of L group was significantly lower than that of S group, but the FcFSTL expression showed an opposite result. After down-regulating the expression of FcMstn by RNAi, FcActRII expression was significantly down-regulated while that of FcFSTL was up-regulated. The present study suggested that FcActRII and FcFSTL, regulated by FcMstn, might be involved in myogenesis and muscle growth. [ABSTRACT FROM AUTHOR]

An emergent shrimp disease, acute hepatopancreatic necrosis disease (AHPND), has been causing great economic losses to the shrimp farming industry. The original causing agent of AHPND was regarded as Vibrio parahaemolyticus , with a plasmid named pVA1 carrying two Photorhabdus insect-related (Pir) toxin genes pir A and pir B. In the present study, a Vibrio owensii strain named FcYS03 was isolated from the Chinese shrimp Fenneropenaeus chinensis , which caused a high mortality in shrimp with typical AHPND signs. This strain carried the binary toxin genes pir AB and could cause AHPND both in Fenneropenaeus chinensis and Penaeus vannamei (previously named Litopenaeus vannamei). The pathogenicity of FcYS03 to P. vannamei exhibited apparent temperature and salinity dependence. Through genome sequence analysis among FcYS03 and AHPND-causing V. parahaemolyticus strain 3HP, we found that a segmental rearrangement phenomenon existed in the plasmid of FcYS03. The toxin genes pir AB happened to be located at the rearranged segment, and two transposases for transposon Tn903 were distributed at the two ends of the rearranged segment, which indicated that transposon Tn903 might be related to the transfer of the toxin genes among the bacteria. The study will provide valuable information for the understanding and prevention of AHPND in shrimp aquaculture. • A strain of Vibrio owensii (FcYS03) causing AHPND was isolated from Fenneropenaeus chinensis. • Its pathogencity to shrimp is water temperature and salinity dependent. • A segmental rearrangement existed in the plasmid of FcYS03 compared with the known plasmid pVA1 in V. parahemolyticus 3HP. [ABSTRACT FROM AUTHOR]

Ras is a small GTP-binding protein that is involved in the regulation of diverse cellular processes, including cell cycle progression, proliferation, and apoptosis. In the present study, a cDNA encoding Ras protein in Chinese shrimp Fenneropenaeus chinensis (designated FcRas) was cloned. The cDNA of FcRas contained a 564 bp open reading frame (ORF), five conserved regions involved in GTP metabolism, and a CAAX motif. Multiple sequence alignment showed that the C-terminal of Ras was less conserved than the N-terminal. In healthy F. chinensis , the FcRas mRNA level in the hepatopancreas and gill were both significantly (P < 0.05) higher than the level in muscle. Following challenge with white spot syndrome virus (WSSV), the FcRas mRNA level in the muscle was significantly (P < 0.05) upregulated at 48 h post-infection (hpi). In the hepatopancreas, the FcRas mRNA level was significantly downregulated at 12 hpi (P < 0.01) and 24 hpi (P < 0.05). The protein level of FcRas in the hepatopancreas was significantly downregulated at 6, 12, 24, and 48 hpi (P < 0.05). These results suggested that the FcRas expression level was influenced by WSSV infection. • A cDNA encoding Ras from Fenneropenaeus chinensis (FcRas) was cloned and sequenced for the first time. • The FcRas mRNA level in the hepatopancreas and muscle changed post white spot syndrome virus challenge. • The FcRas protein level in the hepatopancreas was down-regulated post white spot syndrome virus challenge. [ABSTRACT FROM AUTHOR]