Two new anti-apoptotic proteins of white spot syndrome virus that bind to an effector caspase (PmCasp) of the giant tiger shrimp Penaeus (Penaeus) monodon

Litopenaeus vannamei heat shock protein 90 (LvHSP90) interacts with white spot syndrome virus protein, WSSV322, to modulate hemocyte apoptosis during viral infection

As cellular chaperones, heat shock protein can facilitate viral infection in different steps of infection process. Previously, we have shown that the suppression of Litopenaeus vannamei (Lv)HSP90 not only results in a decline of white spot syndrome virus (WSSV) infection but also induces apoptosis in shrimp hemocyte cells. However, the mechanism underlying how LvHSP90 involved in WSSV infection remains largely unknown. In this study, a yeast two-hybrid assay and co-immunoprecipitation revealed that LvHSP90 interacts with the viral protein WSSV322 which function as an anti-apoptosis protein. Recombinant protein (r) LvHSP90 and rWSSV322 inhibited cycloheximide-induced hemocyte cell apoptosis in vitro. Co-silencing of LvHSP90 and WSSV322 in WSSV-infected shrimp led to a decrease in expression level of viral replication marker genes (VP28, ie-1) and WSSV copy number, while caspase 3/7 activity was noticeably induced. The number of apoptotic cells, confirmed by Hoechst 33342 staining assay and annexin V/PI staining, was significantly higher in LvHSP90 and WSSV322 co-silenced-shrimp than the control groups. Moreover, the co-silencing of LvHSP90 and WSSV322 triggered apoptosis by the mitochondrial pathway, resulting in the upregulation of pro-apoptotic protein expression (bax) and the downregulation of anti-apoptotic protein expression (bcl, Akt). This process also involved the release of cytochrome c (CytC) from the mitochondria and a decrease in mitochondrial membrane potential (MMP). These findings suggest that LvHSP90 interacts with WSSV322 to facilitate viral replication by inhibiting host apoptosis during WSSV infection.

Structural modelling and preventive strategy targeting of WSSV hub proteins to combat viral infection in shrimp Penaeus monodon

White spot syndrome virus (WSSV) presents a considerable peril to the aquaculture sector, leading to notable financial consequences on a global scale. Previous studies have identified hub proteins, including WSSV051 and WSSV517, as essential binding elements in the protein interaction network of WSSV. This work further investigates the functional structures and potential applications of WSSV hub complexes in managing WSSV infection. Using computational methodologies, we have successfully generated comprehensive three-dimensional (3D) representations of hub proteins along with their three mutual binding counterparts, elucidating crucial interaction locations. The results of our study indicate that the WSSV051 hub protein demonstrates higher binding energy than WSSV517. Moreover, a unique motif, denoted as "S-S-x(5)-S-x(2)-P," was discovered among the binding proteins. This pattern perhaps contributes to the detection of partners by the hub proteins of WSSV. An antiviral strategy targeting WSSV hub proteins was demonstrated through the oral administration of dual hub double-stranded RNAs to the black tiger shrimp, Penaeus monodon, followed by a challenge assay. The findings demonstrate a decrease in shrimp mortality and a cessation of WSSV multiplication. In conclusion, our research unveils the structural features and dynamic interactions of hub complexes, shedding light on their significance in the WSSV protein network. This highlights the potential of hub protein-based interventions to mitigate the impact of WSSV infection in aquaculture.

Advances on genomes studies of large DNA viruses in aquaculture: A minireview

Genomic studies of viral diseases in aquaculture have received more and more attention with the growth of the aquaculture industry, especially the emerging and re-emerging viruses whose genome could contain recombination, mutation, insertion, and so on, and may lead to more severe diseases and more widespread infections in aquaculture animals. The present review is focused on aquaculture viruses, which is belonged to two clades, Varidnaviria and Duplodnaviria, and one class Naldaviricetes, and respectively three families: Iridoviridae (ranaviruses), Alloherpesviridae (fish herpesviruses), and Nimaviridae (whispoviruses). The viruses possessed DNA genomes nearly or larger than 100 kbp with gene numbers more than 100 and were considered large DNA viruses. Genome analysis and experimental investigation have identified several genes involved in genome replication, transcription, and virus-host interactions. In addition, some genes involved in virus genetic variation or specificity were also discussed. A summary of these advances would provide reference to future discovery and research on emerging or re-emerging aquaculture viruses.

A new insight into potential roles of Spfoxl-2 in the testicular development of Scylla paramamosain by RNAi and transcriptome analysis

In our previous study, we found that the Spfoxl-2 transcript was highly expressed in gonads and explored its potential target genes in the ovary of Scylla paramamosain. In the current study, we primally analyzed its potential target genes in the testis through RNAi and RNA-Seq technology and compared with that in the ovary. The results showed that a total of 7892 unigenes were differentially expressed after Spfoxl-2 silencing in the testis, including plenty of conserved genes involved in testicular development, such as Dmrt family genes, Sox family genes, Caspase family genes, Cdk family genes, Kinesin family genes, Fox family genes and other genes. Further analysis revealed that these differentially expressed genes (DEGs) were enriched in crucial pathways involved in spermatogenesis, such as DNA replication, Cell cycle, Spliceosome, Homologous recombination, Meiosis and Apoptosis. The comparison results of potential target genes in the ovary and testis reveal 135 common potential target genes, including some genes involved in the immune response. According to our knowledge, the present work was the first to disclose the functions of foxl-2 in the testis of crustacean species using transcriptome analysis. It not only identifies key genes and pathways involved in the testicular development of S. paramamosain, but also reveals a new molecular-level understanding of the function of foxl-2 in testicular development.

Flow cytometry analysis of apoptotic progression and expression analysis of four apoptosis-related genes in Penaeus vannamei in response to white spot syndrome virus infection

Flow cytometry analysis was carried out to detect the progression of apoptosis in haemocytes of WSSV infected Penaeus vannamei at different time-points (1.5 hpi, 18 hpi and 56 hpi). Apoptosis in haemocytes was found to increase with time of infectivity from 5.06 to 69.63%. Quantitative real-time PCR (qPCR) was used for the expression analysis of four apoptosis-related genes such as Death-associated protein 1, caspase-5, translationally controlled tumor protein, and cathepsin D. The evidence of apoptosis in haemocytes of P. vannamei was established as shown by significant increase in the percentage of late apoptotic cells due to WSSV infection in shrimp. The present study gives an insight to the apoptosis rate in a WSSV infected shrimp during the course of infection and the role of apoptosis related genes.

An effector caspase Sp-caspase first identified in mud crab Scylla paramamosain exhibiting immune response and cell apoptosis

Apoptosis plays a key role in the immune defense against pathogen infection, and caspase is one of the most important protease enzyme families, which could initiate and execute apoptosis. Among crustaceans, several caspase genes have been reported. However, caspase in mud crab Scylla paramamosain, have not been identified yet. Here, in the present study, we characterized a new caspase, named as Sp-caspase, from S. paramamosain. The full-length cDNA sequence of Sp-caspase contained 966 bp open reading frame, encoding 322 amino acids, and its molecular weight was 36 kDa. This gene has three conserved domains of the caspase family, a prodomain, a large subunit P20 and a small subunit P10. Phylogenetic analysis showed that Sp-caspase was clustered into an effector caspase group. Sp-caspase mainly distributed in midgut, hepatopancreas, hemocytes and female ovaries, and the transcript was significantly regulated in different tissues after being challenged with Vibrio parahaemolyticus, Vibrio alginolyticus or LPS. After infection with V. alginolyticus, the apoptosis rate of hemocytes notably increased, while the mRNA level of Sp-caspase and hydrolysis activity of caspase 3/7 significantly decreased. Furthermore, in vitro assays showed that the recombinant protein tSp-caspase (deletion of Sp-caspase prodomain) could efficiently recognize and cleave human caspase 3/7 substrate Ac-DEVD-pNA, functioning as an effector caspase. Meanwhile, heterologous expression of Sp-caspase in several cell lines (HEK293T cells, HeLa cells and HighFive cells) could specifically induce cell apoptosis. Taken together, these data demonstrated that Sp-caspase could perform apoptosis as an effector caspase. In addition, it might be a negative regulator of hemocytes apoptosis under pathogen infection, which would contribute to homeostasis and immune defense of hemocytes in S. paramamosain.

The Complete Genome of an Endogenous Nimavirus (Nimav-1_LVa) From the Pacific Whiteleg Shrimp Penaeus (Litopenaeus) Vannamei

White spot syndrome virus (WSSV), the lone virus of the genus Whispovirus under the family Nimaviridae, is one of the most devastating viruses affecting the shrimp farming industry. Knowledge about this virus, in particular, its evolution history, has been limited, partly due to its large genome and the lack of other closely related free-living viruses for comparative studies. In this study, we reconstructed a full-length endogenous nimavirus consensus genome, Nimav-1_LVa (279,905 bp), in the genome sequence of Penaeus (Litopenaeus) vannamei breed Kehai No. 1 (ASM378908v1). This endogenous virus seemed to insert exclusively into the telomeric pentanucleotide microsatellite (TAACC/GGTTA)n. It encoded 117 putative genes, with some containing introns, such as g012 (inhibitor of apoptosis, IAP), g046 (crustacean hyperglycemic hormone, CHH), g155 (innexin), g158 (Bax inhibitor 1 like). More than a dozen Nimav-1_LVa genes are involved in the pathogen-host interactions. We hypothesized that g046, g155, g158, and g227 (semaphorin 1A like) were recruited host genes for their roles in immune regulation. Sequence analysis indicated that a total of 43 WSSV genes belonged to the ancestral/core nimavirus gene set, including four genes reported in this study: wsv112 (dUTPase), wsv206, wsv226, and wsv308 (nucleocapsid protein). The availability of the Nimav-1_LVa sequence would help understand the genetic diversity, epidemiology, evolution, and virulence of WSSV.

miRNAs induced by white spot syndrome virus involve in immunity pathways in shrimp Litopenaeus vannamei

White shrimp Litopenaeus vannamei are widely cultured in the world and white spot syndrome virus (WSSV) led to huge economic losses in the shrimp industry every year. In the present study, miRNAs involved in the response of shrimp L. vannamei to WSSV infection were obtained through the Illumina HiSeq 2500 high-throughput next-generation sequencing technique. A total number of 7 known miRNAs and 54 putative novel miRNAs were obtained. Among them, 14 DEMs were identified in the shrimp infected with WSSV. The putative target genes of these DEMs were related to host immune response or signaling pathways, indicating the importance of miRNAs in shrimp against WSSV infection. The results will provide information for further research on shrimp response to virus infection and contribute to the development of new strategies for effective protection against WSSV infections.

The white spot syndrome virus hijacks the expression of the Penaeus vannamei Toll signaling pathway to evade host immunity and facilitate its replication

The white spot syndrome virus (WSSV), the most lethal pathogen of shrimp, is a dsDNA virus with approximately a 300,000 base pairs and contains approximately 180-500 predicted open reading frames (ORFs), of which only 6% show homology to any known protein from other viruses or organisms. Although most of its ORFs encode enzymes for nucleotide metabolism, DNA replication, and protein modification, the WSSV uses some of its encoded proteins successfully to take control of the metabolism of the host and avoid immune responses. The contribution of the shrimp innate immune response to prevent viral invasions is recognized but yet not fully understood. Thus, the role of several components of Toll pathway of the shrimp Penaeus vannamei against WSSV has been previously described, and the consequential effects occurring through the cascade remain unknown. In the current study the effects of WSSV over various components of the shrimp Toll pathway were studied. The gene expression of Spätzle, Toll, Tube, Cactus and Dorsal was altered after 6-12 h post inoculation. The expression of LvToll3, LvCactus, LvDorsal, decreased ~4.4-, ~3.7- and ~7.3-fold at 48, 24 and 48 hpi, respectively. Furthermore, a remarkable reduction (~18-fold) in the expression of the gene encoding LvCactus in WSSV infected specimens was observed at 6 hpi. This may be a sophisticated strategy exploited by WSSV to evade the Toll-mediated immune action, and to promote its replication, thereby contributing to viral fitness.

Roles of three Es-Caspases during spermatogenesis and Cadmium-induced apoptosis in Eriocheir sinensis

Functions of Caspases remain obscure in Crustacea. We studied the existence and participations of apoptosis-related factors in Eriocheir sinensis testis. Three Es-Caspases (Es-Caspase 3/ 7/ 8) in E. sinensis were cloned and characterized. We observed that three es-caspases mRNA had specific expression patterns during spermiogenesis, with weak signal around the nucleus and invaginated acrosomal vesicle in early-stage spermatids, became stronger in middle-stage, finally focused on the acrosomal tube and nucleus in mature sperm. We then investigated the immunostaining intensity and positional alterations of Es-Caspase 3, Es-Caspase 8 and p53 during spermatogenesis, which were correlated with the differential tendencies of cells to undergo apoptosis and specific organelles shaping processes. After apoptotic induction by Cadmium, Es-Caspase 8 increased gradually, while Es-Caspase 3 increased firstly and then decreased, Es-p53 initially decreased and then increased. These results implies that Es-Caspase 3/ Es-Caspase 8/ p53 may play roles in Cadmium-induced apoptosis during spermatogenesis, and Caspase 8-Caspase 3-p53 pathway may interact with extrinsic or intrinsic pathways to regulate the destiny of sperm cells. Our study revealed the indispensable roles of Caspases during spermatogenesis and the possible molecular interactions in response to the Cadmium-induced apoptosis in E. sinensis, which filled the gap of apoptotic mechanisms of crustacean.

Aquatic animal viruses mediated immune evasion in their host

Viruses are important and lethal pathogens that hamper aquatic animals. The result of the battle between host and virus would determine the occurrence of diseases. The host will fight against virus infection with various responses such as innate immunity, adaptive immunity, apoptosis, and so on. On the other hand, the virus also develops numerous strategies such as immune evasion to antagonize host antiviral responses. Here, We review the research advances on virus mediated immune evasions to host responses containing interferon response, NF-κB signaling, apoptosis, and adaptive response, which are executed by viral genes, proteins, and miRNAs from different aquatic animal viruses including Alloherpesviridae, Iridoviridae, Nimaviridae, Birnaviridae, Reoviridae, and Rhabdoviridae. Thus, it will facilitate the understanding of aquatic animal virus mediated immune evasion and potentially benefit the development of novel antiviral applications.

Identification of a CqCaspase gene with antiviral activity from red claw crayfish Cherax quadricarinatus

Caspase, an aspartate specific proteinase mediating apoptosis, plays a key role in immune response. In our previous study, the expression of a caspase gene was up-regulated in a transcriptome library from the haematopoietic tissue (Hpt) cells of red claw crayfish Cherax quadricarinatus post white spot syndrome virus (WSSV) infection. To further reveal the effect of caspase on WSSV infection, we cloned this caspase gene (denominated as CqCaspase) with an open reading frame of 1062 bp, which encoded 353 amino acids with a caspase domain (CASc) containing a p20 subunit and a p10 subunit. Tissue distribution analysis indicated that the mRNA transcript of CqCaspase was widely expressed in all tested tissues with the highest expression in Hpt, while the lowest expression in muscle. To further explore the effect of CqCaspase on WSSV replication, recombinant protein of CqCaspase (rCqCaspase) was delivered into Hpt cells followed by WSSV infection, which resulted in a significantly decreased expression of both an immediate early gene IE1 and a late envelope protein gene VP28 of WSSV, suggesting that CqCaspase, possibly by the enhanced apoptotic activity, had a strong negative effect on the WSSV replication. These data together indicated that CqCaspase was likely to play a vital role in immune defense against WSSV infection in a crustacean C. quadricarinatus, which shed a new light on the mechanism study of WSSV infection in crustaceans.

WSSV-host interaction: Host response and immune evasion

As invertebrates, shrimps rely on multiple innate defense reactions, including humoral immunity and cellular immunity to recognize and eliminate various invaders, such as viruses. White spot syndrome virus (WSSV) causes the most prevalent and devastating viral disease in penaeid shrimps, which are the most widely cultured species in the coastal waters worldwide. In the last couple of decades, studies about WSSV implicate a dual role of the immune system in protecting shrimps against the infection; these studies also explore on the pathogenesis of WSSV infection. Herein, we review our current knowledge of the innate immune responses of shrimps to WSSV, as well as the molecular mechanisms used by this virus to evade host immune responses or actively subvert them for its own benefit. Deciphering the interactions between WSSV and the shrimp host is paramount to understanding the mechanisms that regulate the balance between immune-mediated protection and pathogenesis during viral infection and to the development of a safe and effective WSSV defensive strategy.

Molecular biology of Macrobrachium rosenbergii nodavirus infection in giant freshwater prawn

Macrobrachium rosenbergii nodavirus (MrNV) has been threatening the giant freshwater prawn aquaculture since 1997, causing white tail disease in the prawn species that leads to 100% lethality of the infected postlarvae. Comprehension of the viral infectivity and pathogenesis at molecular biology level has recently resolved the viral capsid protein and evidenced the significant difference in the viral structural protein compared to other nodaviruses that infect fish and insect. Cumulative researches have remarked the proposal to assert MrNV as a member of new genus, gammanodavirus to the Nodaviridae family. The significance of molecular biology in MrNV infection is being highlighted in this current review, revolving the viral life cycle from virus binding and entry into host, virus replication in host cell, to virus assembly and release. The current review also highlights the emerging aptamers technology that is also known as synthetic antibody, its application in disease diagnosis, and its prophylactic and therapeutic properties. The future perspective of synthetic virology technology in understanding viral pathogenesis, as well as its potential in viral vaccine development, is also discussed.

Shrimp hemocyte homeostasis-associated protein (PmHHAP) interacts with WSSV134 to control apoptosis in white spot syndrome virus infection

Hemocyte homeostasis-associated protein (PmHHAP) was first identified as a viral-responsive gene, due to a high upregulation in transcription following white spot syndrome virus (WSSV) infection. Functional studies using RNA interference have suggested that PmHHAP is involved in hemocyte homeostasis by controlling apoptosis during WSSV infection. In this study, the role of PmHHAP in host-viral interactions was further investigated. Yeast two-hybrid assay and co-immunoprecipitation revealed that PmHHAP binds to an anti-apoptosis protein, WSSV134. The viral protein WSSV134 is a late protein of WSSV, expressed 24 h post infection (hpi). Gene silencing of WSSV134 in WSSV-infected shrimp resulted in a reduction of the expression level of the viral replication marker genes VP28, wsv477, and ie-1, which suggests that WSSV134 is likely involved in viral propagation. However, co-silencing of PmHHAP and WSSV134 counteracted the effects on WSSV infection, which implies the importance of the host-pathogen interaction between PmHHAP and WSSV134 in WSSV infection. In addition, caspase 3/7 activity was noticeably induced in the PmHHAP and WSSV134 co-silenced shrimp upon WSSV infection. Moreover, PmHHAP and WSSV134 inhibited caspase-induced activation of PmCasp in vitro in a non-competitive manner. Taken together, these results suggest that PmHHAP and WSSV134 play a role in the host-pathogen interaction and work concordantly to control apoptosis in WSSV infection.

Transcriptome analysis of Kuruma shrimp (Marsupenaeus japonicus) hepatopancreas in response to white spot syndrome virus (WSSV) under experimental infection

Kuruma shrimp (Marsupenaeus japonicus) is one of the most valuable crustacean species in capture fisheries and mariculture in the Indo-West Pacific. White spot syndrome virus (WSSV) is a highly virulent pathogen which has seriously threatened Kuruma shrimp aquaculture sector. However, little information is available in relation to underlying mechanisms of host-virus interaction in Kuruma shrimp. In this study, we performed a transcriptome analysis from the hepatopancreas of Kuruma shrimp challenged by WSSV, using Illumina-based RNA-Seq. A total of 39,084,942 pair end (PE) reads, including 19,566,190 reads from WSSV-infected group and 19,518,752 reads from non-infected (control) group, were obtained and assembled into 33,215 unigenes with an average length of 503.7 bp and N50 of 601 bp. Approximately 17,000 unigenes were predicted and classified based on homology search, gene ontology, clusters of orthologous groups of proteins, and biological pathway mapping. Differentially expressed genes (DEGs), including 2150 up-regulated and 1931 down-regulated, were found. Among those, 805 DEGs were identified and categorized into 14 groups based on their possible functions. Many genes associated with JAK-STAT signaling pathways, Integrin-mediated signal transduction, Ras signaling pathways, apoptosis and phagocytosis were positively modified after WSSV challenge. The proteolytic cascades including Complement-like activation and Hemolymph coagulations likely participated in antiviral immune response. The transcriptome data from hepatopancreas of Kuruma shrimp under WSSV challenge provided comprehensive information for identifying novel immune related genes in this valuable crustacean species despite the absence of the genome database of crustaceans.

Molecular Mechanisms of White Spot Syndrome Virus Infection and Perspectives on Treatments

Since its emergence in the 1990s, White Spot Disease (WSD) has had major economic and societal impact in the crustacean aquaculture sector. Over the years shrimp farming alone has experienced billion dollar losses through WSD. The disease is caused by the White Spot Syndrome Virus (WSSV), a large dsDNA virus and the only member of the Nimaviridae family. Susceptibility to WSSV in a wide range of crustacean hosts makes it a major risk factor in the translocation of live animals and in commodity products. Currently there are no effective treatments for this disease. Understanding the molecular basis of disease processes has contributed significantly to the treatment of many human and animal pathogens, and with a similar aim considerable efforts have been directed towards understanding host-pathogen molecular interactions for WSD. Work on the molecular mechanisms of pathogenesis in aquatic crustaceans has been restricted by a lack of sequenced and annotated genomes for host species. Nevertheless, some of the key host-pathogen interactions have been established: between viral envelope proteins and host cell receptors at initiation of infection, involvement of various immune system pathways in response to WSSV, and the roles of various host and virus miRNAs in mitigation or progression of disease. Despite these advances, many fundamental knowledge gaps remain; for example, the roles of the majority of WSSV proteins are still unknown. In this review we assess current knowledge of how WSSV infects and replicates in its host, and critique strategies for WSD treatment.

Role of Penaeus monodon hemocyte homeostasis associated protein (PmHHAP) in regulation of caspase-mediated apoptosis

The viral responsive protein, PmHHAP, plays an important role in the control of hemocyte homeostasis in shrimps during viral infection. In this study, we further investigate the role of PmHHAP in the regulation of hemocyte apoptosis. RNA interference (RNAi) mediated gene silencing was used to suppress the PmHHAP expression and the change in hemocyte apoptosis was determined in the knockdown shrimp. Within circulating hemocytes, PmHHAP knockdown increased the number of annexin V-positive apoptotic cells and the combined caspase-3/-7 activity and induced the characteristic apoptotic DNA ladder. Furthermore, PmHHAP down-regulation was accompanied by significantly altered expression of apoptosis-related proteins including the effector caspases, PmCaspase and PmCasp. Yeast two-hybrid and co-immunoprecipitation assays showed that PmHHAP binds to the p20 domain of PmCasp. Moreover, the recombinant PmHHAP protein was able to reduce the caspase activity in the actinomycin D-treated hemocyte cells and rPmCasp-treated hemocyte cells. Taken together, our data indicate that PmHHAP regulates hemocyte homeostasis by inhibits apoptotic cell death through caspase activation.

Interaction study of a novel Macrobrachium rosenbergii effector caspase with B2 and capsid proteins of M. rosenbergii nodavirus reveals their roles in apoptosis

Apoptosis is an essential immune response to protect invertebrates from virus infected cells. In shrimp, virus infection has been reported to induce apoptosis. Macrobrachium rosenbergii (Mr) was considered to be a disease-resistant host when compared to penaeid shrimps. Caspase-3 was classified as an executioner caspase which played a key role in virus-induced apoptosis. In this study, an effector caspase gene of M. rosenbergii (Mrcasp) was cloned and characterized. The open reading frame (ORF) of Mrcasp was 957 nucleotide encoding 318 amino acid with a deduced molecular mass of 35.87 kDa. RT-PCR analysis showed the presence of Mrcasp in all examined tissues. The phylogenetic tree indicated that Mrcasp was closely related with caspase 3 of shrimp. The functions of the Mrcasp, B2 and capsid proteins of M. rosenbergii nodavirus (MrNV) were assayed in Sf-9 cells. The results showed that Mrcasp induce apoptotic morphology cells; however, capsid protein of MrNV could inhibit apoptotic cells whereas B2 could neither induce nor inhibit apoptotic cells by DAPI staining. The protein interaction between Mrcasp and viral MrNV structure revealed that Mrcasp did not bind to B2 or capsid protein whereas B2 and capsid proteins could bind directly to each other. This study reported a novel sequence of a full-length Mrcasp and its functional studies indicated that Mrcasp could induce apoptotic cells. Our data is the first report demonstrating the direct protein-protein interaction between capsid protein and B2 protein of MrNV.

Cellular immune responses against viral pathogens in shrimp

Shrimp is one of the most important commercial marine species worldwide; however, viral diseases threaten the healthy development of shrimp aquaculture. In order to develop efficient control strategies against viral diseases, researchers have begun focusing increasing attention to the molecular mechanism of shrimp innate immunity. Although knowledge of shrimp humoral immunity has grown significantly in recent years, very little information is available about the cell-mediated immune responses. Several cellular processes such as phagocytosis, apoptosis, and RNA interference critical in cellular immune response play a significant role in endogenous antiviral activity in shrimp. In this review, we summarize the emerging research and highlight key mediators of cellular immune response to viral pathogens.