Castration alters the ileum microbiota of Holstein bulls and promotes beef flavor compounds.

BACKGROUND: In the beef industry, bull calves are usually castrated to improve flavor and meat quality; however, this can reduce their growth and slaughter performance. The gut microbiota is known to exert a significant influence on growth and slaughter performance. However, there is a paucity of research investigating the impact of castration on gut microbiota composition and its subsequent effects on slaughter performance and meat flavor. RESULT: The objective of this study was to examine the processes via which castration hinders slaughter productivity and enhances meat quality. Bull and castrated calves were maintained under the same management conditions, and at slaughter, meat quality was assessed, and ileum and epithelial tissue samples were obtained. The research employed metagenomic sequencing and non-targeted metabolomics techniques to investigate the makeup of the microbiota and identify differential metabolites. The findings of this study revealed the Carcass weight and eye muscle area /carcass weight in the bull group were significantly higher than those in the steer group. There were no significant differences in the length, width, and crypt depth of the ileum villi between the two groups. A total of 53 flavor compounds were identified in the two groups of beef, of which 16 were significantly higher in the steer group than in the bull group, and 5 were significantly higher in the bull group than in the steer group. In addition, bacteria, Eukaryota, and virus species were significantly separated between the two groups. The lipid metabolism pathways of α-linolenic acid, linoleic acid, and unsaturated fatty acids were significantly enriched in the Steers group. Compared with the steer group, the organic system pathway is significantly enriched in the bull group. The study also found that five metabolites (LPC (0:0/20:3), LPC (20:3/0:0), LPE (0:0/22:5), LPE (22:5/0:0), D-Mannosamine), and three species (s_Cloning_vector_Hsp70_LexA-HP1, s_Bacteroides_Coprophilus_CAG: 333, and s_Clostridium_nexile-CAG: 348) interfere with each other and collectively have a positive impact on the flavor compounds of beef. CONCLUSIONS: These findings provide a basic understanding that under the same management conditions, castration does indeed reduce the slaughter performance of bulls and improve the flavor of beef. Microorganisms and metabolites contribute to these changes through interactions.

Shrimp SIRT1 activates of the WSSV IE1 promoter independently of the NF-κB binding site.

Since the mechanisms by which cellular factors modulate replication of the shrimp viral pathogen white spot syndrome virus (WSSV) are still largely unknown, here we consider the sirtuins, a family of NAD+-dependent protein deacetylases that are known to function as regulatory factors that activate or suppress viral transcription and replication in mammals. In particular, we focus on SIRT1 by isolating and characterizing LvSIRT1 from white shrimp (Litopenaeus vannamei) and investigating its involvement in WSSV infection. DsRNA-mediated gene silencing led to the expression of WSSV genes and the replication of genomic DNAs being significantly decreased in LvSIRT1-silenced shrimp. The deacetylase activity of LvSIRT1 was significantly induced at the early stage (2 hpi) and the genome replication stage (12 hpi) of WSSV replication, but decreased at the late stage of WSSV replication (24 hpi). Treatment with the SIRT1 activator resveratrol further suggested that LvSIRT1 activation increased the expression of several WSSV genes (IE1, VP28 and ICP11). Lastly, we used transfection and dual luciferase assays in Sf9 insect cells to show that while the overexpression of LvSIRT1 facilitates the promoter activity of WSSV IE1, this enhancement of WSSV IE1 expression is achieved by a transactivation pathway that is NF-κB-independent.

Drying enhances the antioxidant activity of Allium mongolicum Regel through the phenylpropane and AA-MA pathway as shown by metabolomics.

Fresh Allium mongolicum Regel (FA) and dried A. mongolicum Regel (DA) are significantly different in antioxidant activity. However, the relevant mechanisms have not yet been explored. We evaluated the antioxidant activities of two varieties of FA and DA and characterized their metabolites using targeted metabolomics. The effect of different metabolites on the antioxidant activity of A. mongolicum Regel was investigated by multivariate analysis. A total of 713 metabolites were detected in all samples. Pearson correlation analysis demonstrated that the key primary metabolites were directly and significantly correlated with the total phenolic content (TPC) and total flavonoid content (TFC), while the secondary metabolites were directly correlated with antioxidant activity. The higher antioxidant activity of DA may be mainly attributed to the higher TPC and TFC. This study revealed the potential mechanism by which drying enhances the antioxidant activity of A. mongolicum Regel.

Effects of dietary Allium mongolicum Regel powder supplementation on the growth performance, meat quality, antioxidant capacity and muscle fibre characteristics of fattening Angus calves under heat stress conditions.

The aim of this study was to investigate the effects of dietary Allium mongolicum Regel powder (AMRP) supplementation on the growth performance, meat quality, antioxidant capacity and muscle fibre characteristics of fattening Angus calves. Growth performance data and longissimus thoracis (LT) samples were collected from four groups of fattening Angus, which were fed either a basal diet (CON) or a basal diet supplemented with an AMRP dose of 10 (LAMR), 15 (MAMR), or 20 g/animal/day AMRP (HAMR) for 120 days before slaughter. AMRP addition to the feed improved growth performance and meat quality and altered muscle fibre type. Some responses to AMRP supplementation were dose dependent, whereas others were not. Together, the results of this study demonstrated that dietary supplementation with 10 g/animal/day AMRP was the optimal dose in terms of fattening calf growth performance, while 20 g/animal/day AMRP supplementation was the optimal dose in terms of meat quality.

Activity of bovine lactoferrin in resistance to white spot syndrome virus infection in shrimp.

White spot syndrome virus (WSSV) is a notorious pathogen that has plagued shrimp farming worldwide for decades. To date, there are no known treatments that are effective against this virus. Lactoferrin (LF) is a protein with many bioactivities, including antiviral properties. In this study, the activities and mechanisms of bovine LF (bLF) against WSSV were analyzed. Our results showed that bLF treatment significantly reduced shrimp mortalities caused by WSSV infection. bLF was found to have the ability to bind to surfaces of both host cells and WSSV virions. These bindings may have been a result of bLF interactions with the host cellular chitin binding protein and F1 ATP synthase ß subunit protein and the WSSV structural proteins VP28, VP110, VP150 and VP160B. bLF demonstrated potential for development as an anti-WSSV agent in shrimp culture. Furthermore, these reactionary proteins may play a role in WSSV infection.

Penaeus monodon TATA box-binding protein interacts with the white spot syndrome virus transactivator IE1 and promotes its transcriptional activity.

We show here that the white spot syndrome virus (WSSV) immediate-early protein IE1 interacts with the Penaeus monodon TATA box-binding protein (PmTBP) and that this protein-protein interaction occurs in the absence of any other viral or cellular proteins or nucleic acids, both in vitro and in vivo. Mapping studies using enhanced green fluorescent protein (EGFP) fusion proteins containing truncations of IE1 and PmTBP delimited the interacting regions to amino acids (aa) 81 to 180 in IE1 and, except for aa 171 to 230, to aa 111 to 300 in PmTBP. A WSSV IE1 transactivation assay showed that large quantities (>800 ng) of the GAL4-IE1 plasmid caused "squelching" of the GAL4-IE1 activity and that this squelching effect was alleviated by the overexpression of PmTBP. Gene silencing of WSSV ie1 and PmTBP by pretreatment with double-stranded RNAs (dsRNAs) prior to WSSV challenge showed that the expression of these two target genes was specifically inhibited by their corresponding dsRNAs 72 and 96 h after dsRNA treatment. dsRNA silencing of ie1 and PmTBP expression also significantly reduced WSSV replication and the expression of the viral early gene dnapol (DNA polymerase gene). These results suggest that WSSV IE1 and PmTBP work cooperatively with each other during transcription initiation and, furthermore, that PmTBP is an important target for WSSV IE1's transactivation activity that can enhance viral gene expression and help in virus replication.

Feeding hermit crabs to shrimp broodstock increases their risk of WSSV infection.

White spot syndrome virus (WSSV) is a serious shrimp pathogen that has spread globally to all major shrimp farming areas, causing enormous economic losses. Here we investigate the role of hermit crabs in transmitting WSSV to Penaeus monodon brooders used in hatcheries in Vietnam. WSSV-free brooders became PCR-positive for WSSV within 2 to 14 d, and the source of infection was traced to hermit crabs being used as live feed. Challenging hermit crabs with WSSV confirmed their susceptibility to infection, but they remained tolerant to disease even at virus loads equivalent to those causing acute disease in shrimp. As PCR screening also suggests that WSSV infection occurs commonly in hermit crab populations in both Vietnam and Taiwan, their use as live feed for shrimp brooders is not recommended.

Adding of Allium mongolicum regel extracts to lamb feedlot diets influences 4-alkyl-branched fatty acids deposition and the meat quality during storage.

The present study aimed to investigate the effect of dietary supplementation with Allium mongolicum Regel extracts on the 4-alkyl-branched fatty acid deposition and meat quality during storage. Small-tailed Han sheep were divided into four groups (n = 15) and fed for 75 days with a basal diet (CK), CK supplemented with A. mongolicum Regel powder (AMR), A. mongolicum Regel water-soluble extract (AWE), or A. mongolicum Regel ethanol-soluble extract (AFE). The results revealed that both AMR and AWE diets decreased the 4-alkyl-branched fatty acids content in longissimus thoracis. Diet × storage time interactions were observed for acid value (AV), peroxidase (POx), glutathione peroxidase (GSH-Px), and total volatile base nitrogen (TVB-N). Patterns of change for AV, POx, and GSH-Px over time leading to the interactions were not readily apparent and changes were more governed by main effects. Dietary supplementation with AMR and AWE increased the total antioxidant capacity, total superoxide dismutase, and inhibited total bacteria counts compared to those in the CK lambs. The AWE diet also decreased the yellowness and hue angle. Overall, A. mongolicum Regel and its extracts could be used as a source of natural bioactive compounds in the lambs' diet to extend the storage time of their meat.

Demethylation of an artificial hydrogenase agent for prolonged CO release and enhanced anti-tau aggregation activity.

Carbon monoxide (CO) plays an important role in signaling in cells, making its use as a therapeutic tool highly intriguing. Reduced burst emissions are important to avoid the cytotoxicity and tissue damage caused by CO. Here, we developed a stable diiron carbonyl [FeFe] hydrogenase agent that enables prolonged CO release activity (half-life of over 9 h) in cells. The integrated analysis allowed the identification of the key intermediate sites and CO accumulations with subcellular resolution. We observed that the [FeFe]A complex was enriched in neurons with S-methyl bond rupture. Furthermore, the [FeFe]A complex efficiently reduced the aggregation of tau proteins (49.3% reduction) and showed superior biocompatibility in nerve cells (∼ 95% survival).

Xenograft cancer vaccines prepared from immunodeficient mice increase tumor antigen diversity and host T cell efficiency against colorectal cancers.

Autologous cancer vaccines (ACVs) are a desirable approach for personalized medicine, but the efficiency of ACVs remains unsatisfactory due to their low immunogenicity. This study developed a platform that can enhance the immunogenicity of ACVs by transplanting the tumors into immunodeficient mice. The CT26 cell line was inoculated into severe combined immunodeficient mice (SCID) for vaccine preparation where escalates tumor development, subsequently diversifying the tumor antigenic topology. CT26/SCID cancer vaccines significantly inhibited tumor growth, increased the amount of tumor infiltrating lymphocytes, and triggered Th-1 predominant immune responses. Tumor antigenic profiles of CT26/SCID cells were further analyzed by liquid chromatography-tandem mass spectrometry. Compared to CT26 parental cells, a total of 428 differentially expressed proteins (DEPs) were detected. These DEPs revealed that CT26/SCID cells overexpressed several novel therapeutic targets, including KNG1, apoA-I and, ß2-GPI, which can trigger cytotoxic T cells towards Th-1 predominant immune responses and directly suppress proliferation in tumors. CT26/SCID cancer vaccines can be easily manufactured, while traits of triggering stronger antigen-specific Th-1 immune activity against tumors, are retained. Results of this study provide an effective proof-of-concept of an ACV for personalized cancer immunotherapy.

Effect of dietary supplementation with Allium mongolicum Regel extracts on growth performance, carcass characteristics, and the fat color and flavor-related branched-chain fatty acids concentration in ram lambs.

OBJECTIVE: This study aimed to investigate the effect of dietary supplementation with Allium mongolicum Regel extracts on the growth performance, carcass characteristics, fat color, and concentrations of three branched-chain fatty acids related to flavor in ram lambs. METHODS: Sixty 3-month-old, male, small-tailed Han sheep were selected and randomly allocated into four groups in a randomized block design. Four feeding treatments were used: i) a basal diet without supplementation as the control group (CK); ii) the basal diet supplemented with 10 g/lamb/d Allium mongolicum Regel powder as the AMR group; iii) the basal diet supplemented with 3.4 g/lamb/d Allium mongolicum Regel water extract as the AWE group; and iv) the basal diet supplemented with 2.8 g/lamb/d Allium mongolicum Regel ethanol extract as the AFE group. RESULTS: The results demonstrated that the dry matter intake was lower for the AFE group than that in other groups (p = 0.001). The feed conversion ratio was greater for the AFE than that in other groups (p = 0.039). Dietary supplementation with Allium mongolicum Regel powder and its extracts decreased the concentrations of 4-methyloctanoic acid (MOA) (p<0.001), 4-ethyloctanoic acid (EOA) (p<0.001), and 4-methylnonanoic acid (MNA) (p = 0.044) in perirenal adipose tissue compared to those observed in the CK lambs. Dietary supplementation with Allium mongolicum Regel powder and its extracts decreased the concentrations of MOA (p<0.001) and EOA (p<0.001) in dorsal subcutaneous adipose tissue compared to those in the CK lambs. The concentrations of MOA (p<0.001) and EOA (p = 0.002) in omental adipose tissue were significantly affected by treatment, although there was a tendency for lower MNA (p = 0.062) in AMR, AWE, and AFE lambs than that in CK lambs. CONCLUSION: This study demonstrated that Allium mongolicum Regel and its extracts could significantly promote feed efficiency, although dry matter intake decreased and could decrease the MOA and EOA concentrations related to characteristic flavor and odor of body fat in lambs, except for tail adipose tissue.

Effects of dietary supplementation with Allium mongolicum Regel extracts on growth performance, serum metabolites, immune responses, antioxidant status, and meat quality of lambs.

The present study was to evaluate the effects of dried Allium mongolicum Regel (AMR) powder and its water- and fat-soluble extracts (AWE and AFE) on the growth performance, serum metabolites, immune responses, antioxidant status, and meat quality of lambs. A total of 32 male small-tailed Han lambs (5 months old; initial body weight = 34.8 ± 0.40 kg) were used in a 60-d feeding experiment after a 15-d adaptation period. The lambs were randomly divided into 4 groups (n = 8) and fed a basal diet (control, CON group), the basal diet supplemented with dried AMR powder at 10 g/d per lamb (AMR group), the basal diet supplemented with AWE at 3.4 g/d per lamb (AWE group), or the basal diet supplemented with AFE at 2.8 g/d per lamb (AFE group). Blood samples were collected on d 0, 30, and 60 in the feeding experiment (n = 8). At the end of the experiment, the lambs were sacrificed and the longissimus dorsi muscles collected. Growth performance was not significantly affected by dietary supplementation of AMR, AWE and AFE (P > 0.05). However, significantly lower albumin (P = 0.006), total protein (P = 0.006), globin (P = 0.025), and blood urea nitrogen (P = 0.024) concentrations were observed in AFE group relative to CON and AMR groups. Similarly, a significantly lower lactate dehydrogenase activity (P = 0.018) was observed in AFE group relative to AWE group, but not in other groups (P > 0.05). In addition, significantly increasing trends in glutathione peroxidase (P = 0.06) in AMR, AWE, and AFE groups were observed relative to the control group. Furthermore, significantly lower drip loss (P = 0.011) across the treatment groups and cooking loss (P = 0.048) were observed in the AMR group relative to the control group. Taken together, these results indicate that AMR and its extracts had no significant effect on lamb growth performance, antioxidant status, and immune responses, but could significantly improve meat quality without the occurrence of pathological kidney and liver lesions.

F1 ATP synthase ß subunit is a putative receptor involved in white spot syndrome virus infection in shrimp by binding with viral envelope proteins VP51B and VP150.

White spot syndrome virus (WSSV) is highly virulent toward shrimp, and F1 ATP synthase ß subunit (ATPsyn-ß) has been suggested to be involved in WSSV infection. Therefore, in this study, interactions between Penaeus monodon ATPsyn-ß (PmATPsyn-ß) and WSSV structural proteins were characterized. Based on the results of yeast two-hybrid, co-immunoprecipitation, and protein pull-down assays, WSSV VP51B and VP150 were identified as being able to interact with PmATPsyn-ß. Membrane topology assay results indicated that VP51B and VP150 are envelope proteins with large portions exposed outside the WSSV virion. Cellular localization assay results demonstrated that VP51B and VP150 co-localize with PmATPsyn-ß on the membranes of transfected cells. Enzyme-linked immunosorbent assay (ELISA) and competitive ELISA results demonstrated that VP51B and VP150 bound to PmATPsyn-ß in a dose-dependent manner, which could be competitively inhibited by the addition of WSSV virions. In vivo neutralization assay results further showed that both recombinant VP51B and VP150 could delay mortality in shrimp challenged with WSSV.

Transactivation, dimerization, and DNA-binding activity of white spot syndrome virus immediate-early protein IE1.

Immediate-early proteins from many viruses function as transcriptional regulators and exhibit transactivation activity, DNA binding activity, and dimerization. In this study, we investigated these characteristics in white spot syndrome virus (WSSV) immediate-early protein 1 (IE1) and attempted to map the corresponding functional domains. Transactivation was investigated by transiently expressing a protein consisting of the DNA binding domain of the yeast transactivator GAL4 fused to full-length IE1. This GAL4-IE1 fusion protein successfully activated the Autographa californica multicapsid nucleopolyhedrovirus p35 basal promoter when five copies of the GAL4 DNA binding site were inserted upstream of the TATA box. A deletion series of GAL4-IE1 fusion proteins suggested that the transactivation domain of WSSV IE1 was carried within its first 80 amino acids. A point mutation assay further showed that all 12 of the acidic residues in this highly acidic domain were important for IE1's transactivation activity. DNA binding activity was confirmed by an electrophoresis mobility shift assay using a probe with (32)P-labeled random oligonucleotides. The DNA binding region of WSSV IE1 was located in its C-terminal end (amino acids 81 to 224), but mutation of a putative zinc finger motif in this C-terminal region suggested that this motif was not directly involved in the DNA binding activity. A homotypic interaction between IE1 molecules was demonstrated by glutathione S-transferase pull-down assay and a coimmunoprecipitation analysis. A glutaraldehyde cross-linking experiment and gel filtration analysis showed that this self-interaction led to the formation of stable IE1 dimers.

Characterization of white spot syndrome virus envelope protein VP51A and its interaction with viral tegument protein VP26.

In this study, we characterize a novel white spot syndrome virus (WSSV) structural protein, VP51A (WSSV-TW open reading frame 294), identified from a previous mass spectrometry study. Temporal-transcription analysis showed that vp51A is expressed in the late stage of WSSV infection. Gene structure analysis showed that the transcription initiation site of vp51A was 135 bp upstream of the translation start codon. The poly(A) addition signal overlapped with the translation stop codon, TAA, and the poly(A) tail was 23 bp downstream of the TAA. Western blot analysis of viral protein fractions and immunoelectron microscopy both suggested that VP51A is a viral envelope protein. Western blotting of the total proteins extracted from WSSV virions detected a band that was close to the predicted 51-kDa mass, but the strongest signal was around 72 kDa. We concluded that this 72-kDa band was in fact the full-length VP51A protein. Membrane topology assays demonstrated that the VP51A 72-kDa protein is a type II transmembrane protein with a highly hydrophobic transmembrane domain on its N terminus and a C terminus that is exposed on the surface of the virion. Coimmunoprecipitation, colocalization, and yeast two-hybrid assays revealed that VP51A associated directly with VP26 and indirectly with VP28, with VP26 acting as a linker protein in the formation of a VP51A-VP26-VP28 complex.

Cloning and expression of the lectin gene from the mushroom Agrocybe aegerita and the activities of recombinant lectin in the resistance of shrimp white spot syndrome virus infection.

Lectin is a protein with multiple functions. In this study, the full-length cDNA of the Agrocybe aegerita lectin (AAL) gene was cloned, recombinant AAL (AAL-His) was expressed, and the activities of AAL-His were analyzed. Northern blot analysis showed that the major AAL transcript is approximately 900 bp. Sequence analysis showed that the coding region of AAL is 489 bp with a transcription start site located 39 nucleotides upstream of the translation initiation codon. In an agglutination test, AAL-His agglutinated rabbit erythrocytes at 12.5 µg/ml. AAL-His also showed antiviral activity in protecting shrimp from white spot syndrome virus (WSSV) infection. This anti-WSSV effect might be due to the binding of AAL-His on WSSV virions via the direct interactions with four WSSV structural proteins, VP39B, VP41B, VP53A and VP216. AAL demonstrates the potential for development as an anti-WSSV agent for shrimp culture. It also implies that these four AAL interaction WSSV proteins may play important roles in virus infection.

Laminin Receptor in Shrimp Is a Cellular Attachment Receptor for White Spot Syndrome Virus.

White spot syndrome virus (WSSV, genus Whispovirus, family Nimaviridae) is causing huge economic losses in global shrimp farming, but there is no effective control. Shrimp cell laminin receptor (Lamr) may have a role in WSSV infection. The objective was to characterize interactions between Penaeus monodon Lamr (PmLamr) and WSSV structural proteins. In this study, PmLamr interacted with nine WSSV structural proteins (based on yeast two-hybrid screening), of which one (VP31) was characterized. Protein pull-down assay confirmed the interaction between PmLamr and VP31; the latter was an envelope protein exposed outside the WSSV virion (based on membrane topology assays). Furthermore, similar to mammalian Lamr, there were two major protein bands in shrimp cells. Cellular localization assay demonstrated VP31 co-localized with PmLamr on transfected cells. Enzyme-link immunosorbent assay (ELISA) and competitive ELISA demonstrated binding of VP31 on PmLamr was dose-dependent; however, addition of WSSV virion competed for binding affinity. Furthermore, based on an in vivo neutralization assay, both VP31 and PmLamr delayed mortality in shrimp challenged with WSSV. We concluded Lamr was an important receptor for WSSV infection and the viral envelope protein VP31 may have a role in host cell recognition and binding. These data contributed to elucidating pathogenesis of WSSV infection and may help in controlling this disease.

The promoter of the white spot syndrome virus immediate-early gene WSSV108 is activated by the cellular KLF transcription factor.

A series of deletion and mutation assays of the white spot syndrome virus (WSSV) immediate-early gene WSSV108 promoter showed that a Krüppel-like factor (KLF) binding site located from -504 to -495 (relative to the transcription start site) is important for the overall level of WSSV108 promoter activity. Electrophoretic mobility shift assays further showed that overexpressed recombinant Penaeus monodon KLF (rPmKLF) formed a specific protein-DNA complex with the (32)P-labeled KLF binding site of the WSSV108 promoter, and that higher levels of Litopenaeus vannamei KLF (LvKLF) were expressed in WSSV-infected shrimp. A transactivation assay indicated that the WSSV108 promoter was strongly activated by rPmKLF in a dose-dependent manner. Lastly, we found that specific silencing of LvKLF expression in vivo by dsRNA injection dramatically reduced both WSSV108 expression and WSSV replication. We conclude that shrimp KLF is important for WSSV genome replication and gene expression, and that it binds to the WSSV108 promoter to enhance the expression of this immediate-early gene.

Characterization and interactome study of white spot syndrome virus envelope protein VP11.

White spot syndrome virus (WSSV) is a large enveloped virus. The WSSV viral particle consists of three structural layers that surround its core DNA: an outer envelope, a tegument and a nucleocapsid. Here we characterize the WSSV structural protein VP11 (WSSV394, GenBank accession number AF440570), and use an interactome approach to analyze the possible associations between this protein and an array of other WSSV and host proteins. Temporal transcription analysis showed that vp11 is an early gene. Western blot hybridization of the intact viral particles and fractionation of the viral components, and immunoelectron microscopy showed that VP11 is an envelope protein. Membrane topology software predicted VP11 to be a type of transmembrane protein with a highly hydrophobic transmembrane domain at its N-terminal. Based on an immunofluorescence assay performed on VP11-transfected Sf9 cells and a trypsin digestion analysis of the virion, we conclude that, contrary to topology software prediction, the C-terminal of this protein is in fact inside the virion. Yeast two-hybrid screening combined with co-immunoprecipitation assays found that VP11 directly interacted with at least 12 other WSSV structural proteins as well as itself. An oligomerization assay further showed that VP11 could form dimers. VP11 is also the first reported WSSV structural protein to interact with the major nucleocapsid protein VP664.

Role of Penaeus monodon Kruppel-like factor (PmKLF) in infection by white spot syndrome virus.

Sp1-like proteins and Kruppel-like factors (KLFs) are highly related zinc-finger proteins that have crucial roles in transcription. One expressed sequence tag (EST, HPA-N-S01-EST0038) from shrimps is homologous to Sp1. This study reports the cloning and characteristics of a KLF from shrimp, Penaeus monodon (PmKLF). The full-length PmKLF cDNA is 1702 bp, encoding a polypeptide of 360 amino acids. Sequence analysis revealed that the sequence of PmKLF is similar to that of KLF11 in humans, mice and zebrafish. RT-PCR analysis indicated that PmKLF mRNA is expressed in all examined tissues. Additionally, immunofluorescence analysis revealed that GFP-KLF fusion protein is located in the nucleus as dots in an insect cell line, Sf9. Localization of PmKLF in the nucleus is also observed in the hemolymph from white spot syndrome virus (WSSV)-infected and WSSV-uninfected Litopenaeus vannamei. Knockdown of the expression of PmKLF transcript in WSSV-infected shrimp resulted in delayed cumulative mortalities, suggesting that PmKLF is important to WSSV infection. Moreover, inhibition of PmKLF expression reduced the copy number of WSSV and ie1 expression, revealing that PmKLF affects WSSV infection via interfering with ie1 expression.