Vibrio Parahaemolyticus Infection Research Articles

Elevated temperature and decreased salinity impacts on exogenous Vibrio parahaemolyticus infection of eastern oyster, Crassostrea virginica

Elevated temperature and decreased salinity impacts on exogenous Vibrio parahaemolyticus infection of eastern oyster, Crassostrea virginica

Risk Factors and Effects of Climate Lag on Vibrio Parahaemolyticus Infection in Eastern Coastal Cities of China: A Study Based on Hangzhou City.

Bacterial foodborne diseases caused by Vibrio parahaemolyticus pose persistent challenges to coastal cities in China. In this study, we employed multiple logistic regression analysis and distributed lag non-linear models (DLNM) to investigate the epidemiological characteristics and associated risk factors of vibriosis in the metropolitan area of Hangzhou from 2014 to 2018. Analysis of foodborne cases indicated that certain demographics and occupational factors, including age between 16 and 44 years; houseworkers or unemployed individuals; preference for aquatic and meat products; and dining in collective canteens or catering services contribute to an increased likelihood of V. parahaemolyticus infection. Moreover, a higher per capita GDP and exposure to high temperatures were identified as risk factors for vibriosis. This study highlights the significance of the daily mean temperature as a meteorological factor influencing V. parahaemolyticus infection, with varying lag effects observed depending on temperature conditions. At low temperatures, the risk of infection occurs after a lag of 21 days, whereas at high temperatures, the risk is highest on the same day, while the second infection risk period occurs after a lag of 21 days. These findings provide a spatiotemporal perspective of the risk analysis of foodborne diseases, with a daily timescale and street spatial scale, which contributes to the development of public health strategies and food safety protocols in coastal cities.

In silico identification and functional study of long non-coding RNA involved in acute hepatopancreatic necrosis disease caused by Vibrio parahaemolyticus infection in white shrimp, Litopenaeus vannamei

Acute hepatopancreatic necrosis disease (AHPND) caused by toxin-producing Vibrio parahaemolyticus (VpAHPND) has severely affected shrimp production. Long non-coding RNA (lncRNA), a regulatory non-coding RNA, which can play important function in shrimp disease resposnes. This study aimed to identify and investigate the role of lncRNA involved in VpAHPND infection in Pacific white shrimp, Litopenaeus vannamei. From a total of 368,736 de novo assembled transcripts, 67,559 were identified as putative lncRNAs, and only 72 putative lncRNAs showed differential expression between VpAHPND-infected and normal shrimp. The six candidate lncRNAs were validated for their expression profiles during VpAHPND infection and tissue distribution using RT-qPCR. The role of lnc2088 in response to VpAHPND infection was investigated through RNA interference. The result indicated that the suppression of lnc2088 expression led to an increase in shrimp mortality after VpAHPND infection. To explore the set of genes involved in lnc2088 knockdown, RNA sequencing was performed. A total of 275 differentially expressed transcripts were identified in the hepatopancreas of lnc2088 knockdown shrimp. The expression profiles of five candidate metabolic and immune-related genes were validated in lnc2088 knockdown and VpAHPND-infected shrimp. The result showed that the expression of ChiNAG was significantly increased, while that of NCBP1, WIPF2, and NFKB1 was significantly downregulated in ds2088-injected shrimp. Additionally, the expression of NFKB1, NCBP1 and WIPF2 was significantly increased, whereas that of ChiNAG and CUL5 were significantly decreased after infection with VpAHPND. Our work identified putative lncRNA profiles in L. vannamei in response to VpAHPND infection and investigated the role of lncRNA in shrimp immunity.

Identification of toll-like receptor family and the immune function of new Sptlr-6 gene of Scylla paramamosain

As a crucial member of pattern-recognition receptors (PRRs), the Tolls/Toll-like receptors (TLRs) gene family has been proven to be involved in innate immunity in crustaceans. In this study, nine members of TLR gene family were identified from the mud crab (Scylla paramamosain) transcriptome, and the structure and phylogeny of different SpTLRs were analyzed. It was found that different SpTLRs possessed three conserved structures in the TIR domain. Meanwhile, the expression patterns of different Sptlr genes in examined tissues detected by qRT-PCR had wide differences. Compared with other Sptlr genes, Sptlr-6 gene was significantly highly expressed in the hepatopancreas and less expressed in other tissues. Therefore, the function of Sptlr-6 was further investigated. The expression of the Sptlr-6 gene was up-regulated by Poly I: C, PGN stimulation and Vibrio parahaemolyticus infection. In addition, the silencing of Sptlr-6 in hepatopancreas mediated by RNAi technology resulted in the significant decrease of several conserved genes involved in innate immunity in mud crab after V. parahaemolyticus infection, including relish, myd88, dorsal, anti-lipopolysaccharide factor (ALF), anti-lipopolysaccharide factor 2 (ALF-2) and glycine-rich antimicrobial peptide (glyamp). This study provided new knowledge for the role of the Sptlr-6 gene in defense against V. parahaemolyticus infection in S. paramamosain.

Assessment of fish protein hydrolysate as a substitute for fish meal in white shrimp diets: Impact on growth, immune response, and resistance against Vibrio parahaemolyticus infection

This study investigated the effects of fish protein hydrolysate derived from barramundi on growth performance, muscle composition, immune response, disease resistance, histology and gene expression in white shrimp (Penaeus vannamei). In vitro studies demonstrated FPH enhanced mRNA expressions of key immune-related genes and stimulated reactive oxygen species (ROS) production and phagocytic activity in shrimp hemocytes. To evaluate the effects of substituting fish meal with FPH in vivo, four isoproteic (43 %), isolipidic (6 %), and isoenergetic diets (489 kcal/100 g) were formulated with fish meal substitution levels of 0 % (control), 30 % (FPH30), 65 % (FPH65), and 100 % (FPH100). After 8-week feeding, the growth performance of FPH65 and FPH100 were significantly lower than that of control and FPH30 (p < 0.05). Similarly, the midgut histological examination revealed the wall thickness and villi height of FPH100 were significantly lower than those of control (p < 0.05). The shrimps were received the challenge of AHPND + Vibrio parahaemolyticus at week 4 and 8. All FPH-fed groups significantly enhanced resistance against Vibrio parahaemolyticus at week 4 (p < 0.05). However, this protective effect diminished after long-period feeding. No significant difference of survival rate was observed among all groups at week 8 (p > 0.05). The expressions of immune-related genes were analyzed at week 4 before and after challenge. In control group, V. parahaemolyticus significantly elevated SOD in hepatopancreas and Muc 19, trypsin, Midline-fas, and GPx in foregut (p < 0.05). Moreover, hepatopancreatic SOD of FPH65 and FPH100 were significantly higher than that of control before challenge (p < 0.05). Immune parameters were measured at week 8. Compared with control, the phagocytic index of FPH 30 was significantly higher (p < 0.05). However, dietary FPH did not alter ROS production, phenoloxidase activity, phagocytic rate, and total hemocyte count (p > 0.05). These findings suggest that FPH30 holds promise as a feed without adverse impacts on growth performance while enhancing the immunological response of white shrimp.

Effect of Formic Acid and Biotin Supplementation on Growth Performance and Survival of the Carp Fish Challenged with Vibrio parahaemolyticus Infection

Effect of Formic Acid and Biotin Supplementation on Growth Performance and Survival of the Carp Fish Challenged with Vibrio parahaemolyticus Infection

Dietary supplementation of micelle silymarin enhances the antioxidant status, innate immunity, growth performance, resistance against Vibrio parahaemolyticus infection, and gut morphology in Pacific white shrimp (Litopenaeus vannamei)

Silymarin, a flavonoid compound derived from the milk thistle plant (Silybum marianum) is well-known for its hepatoprotective, antioxidant, immunomodulatory, and anti-inflammatory properties. Therefore, this study sought to evaluate the effect of silymarin and micelle silymarin (MS) supplementation on Pacific white shrimp (Litopenaeus vannamei). The experimental diets were formulated to include MS at levels of 0.25, 0.5, 1.0, 2.0, and 4.0 g/kg or silymarin at levels of 1.0 and 2.0 g/kg in the basal diet (Con, M0.25, M0.5, M1, M2, M4, S1 and S2, respectively). Juvenile shrimp (0.98 g) were fed with experimental diets (four replicates) for 42 days. The growth metrics were significantly (P < 0.05) increased in M0.25, M0.5, and M1 groups compared to the Con group. Feed conversion ratio decreased (P < 0.05) in M0.5, M1, and M2 groups, whereas the protein efficiency ratio increased (P < 0.05) in M0.5 and M1 groups compared to the Con group. Phenoloxidase, lysozyme, glutathione peroxidase, and superoxide dismutase activities were enhanced (P < 0.05), with the highest levels observed in the M0.5 group. Malondialdehyde level decreased (P < 0.05) in M1 and M2 groups compared to the Con group. Total protein increased (P < 0.05) in M0.25, M0.5 and S1 groups compared to the Con group. AST levels were significantly reduced (P < 0.05) in shrimp fed M0.5, M1, M2, M4, and S2 groups, and ALT levels decreased (P < 0.05) in M1 and S2 groups compared to Con group. Wall thickness was significantly higher (P < 0.05) in the M0.5 group, and villi length increased (P < 0.05) in M0.25, M0.5, and S1 groups. The resistance against Vibrio parahaemolyticus increased; however, no significant differences in cumulative survival were observed (P ˃ 0.05). Significantly higher (P < 0.05) proPO levels were observed in M0.5, M1, M2, M4, and S2 groups, whereas higher (P < 0.05) TLR-3 levels were observed in M1 and M2 groups compared to the Con group. TNF-α expression decreased (P < 0.05) in all other dietary treatments compared to the Con group. The findings suggest that dietary silymarin and MS can enhance growth, immune response, antioxidant capacity, gut morphology, and immune gene expression, while reducing lipid peroxidation and inflammation in Pacific white shrimp. The shrimp performance shows no significant difference between silymarin and MS groups at 1% and 2% levels. The optimal suggested inclusion level of MS in shrimp feed is 0.5–1.0 g/kg.

Unveiling the positive impact of biofloc culture on Vibrio parahaemolyticus infection of Pacific white shrimp by reducing quorum sensing and virulence gene expression and enhancing immunity.

This study aimed to evaluate and unveil the positive impact of biofloc culture on Vibrio parahaemolyticus infection of Pacific white shrimp by reducing quorum sensing (QS) and virulence gene expression and enhancing shrimp's immunity. The shrimp with an average body weight of 0.50 ± 0.09 g were reared in containers with a volume of 2.5 L, 21 units, and a density of 20 shrimp L-1. The shrimp were cultured for 5 days, with each treatment including biofloc system maintenance with a C/N ratio of 10 and a control treatment without biofloc, followed by a challenge test through immersion using V. parahaemolyticus at densities of 103, 105, and 107 CFU mL-1 initially. The results of the invitro experiment showed that biofloc suspension can inhibit and disperse biofilm formation, as well as reduce the exo-enzyme activity (amylase, protease, and chitinase) of V. parahaemolyticus. Furthermore, the biofloc treatment significantly reduced the expression of the QS regulatory gene OpaR, the PirB toxin gene, and the virulence factor genes T6SS1 and T6SS2 in both invitro and invivo. The biofloc system also increased the expression of shrimp immunity-related genes (LGBP, proPO, SP, and PE) and the survival rate of white shrimp challenged with V. parahaemolyticus.

Characterization of a pseudohemocyanin gene (PtPhc1) and its immunity function in response to Vibrio parahaemolyticus infection in the swimming crab Portunus trituberculatus

Pseudohemocyanin is a member of the hemocyanin superfamily, but little research is available on its function in immunology. In this study, a Portunus trituberculatus pseudohemocyanin gene, named PtPhc1, was obtained by gene cloning. The PtPhc1 cDNA was 2312 bp in length, encoding 684 amino acids while exhibiting a characteristic hemocyanin structural domain. Tissue expression analysis revealed ubiquitous expression of PtPhc1 across all tissues, with the highest level of expression observed in the hepatopancreas. The expression pattern of PtPhc1 in response to Vibrio parahaemolyticus infection was clarified using RT-qPCR in swimming crabs. Notably, the expression peaked at 24 h, and increased 1435-fold compared to the control group in the hepatopancreas. While the expression level reached the maximum value at 72 h, which was 3.24 times higher than that of the control group in hemocytes. Remarkably, the reduction in PtPhc1 expression led to a noteworthy 30% increase in the mortality rate of P. trituberculatus when exposed to V. parahaemolyticus. In addition, in vitro bacterial inhibition assays exhibited a dose-dependent suppression of bacterial proliferation by recombinant PtPhc1 protein, with a notable inhibition rate of 48.33% against V. parahaemolyticus at a concentration of 0.03 mg/mL. To the best of our knowledge, the results establish the function of pseudohaemocyanin in immunity for the first time, contributing to a deeper comprehension of innate immune regulatory mechanisms in aquatic organisms and advancing strategies for disease-resistant breeding.

Characterization of the antibacterial and opsonic functions of the antimicrobial peptide LvCrustinVI from Litopenaeus vannamei

Microbial drug resistance is becoming increasingly severe due to antibiotic abuse. The development and utilization of antimicrobial peptides is one of the important ways to solve this difficult problem. Crustins are a family of antimicrobial peptides that play important roles in the innate immune system of crustaceans. Several types of crustins exist in shrimp and their activities vary greatly. In the present study, we studied the immune function of one newly identified crustin and found that the type VI crustin encoding gene in Litopenaeus vannamei (LvCrustinVI) was mainly expressed in gills. Its expression was significantly up-regulated after Vibrio parahaemolyticus infection and knockdown of the gene promoted Vibrio proliferation in the hepatopancreas of shrimp, indicating that LvCrustinVI was involved in pathogens infection. The recombinant LvCrustinVI (rLvCrustinVI) showed strong inhibitory activities against both Gram-negative and Gram-positive bacteria, and exhibited binding activities with the bacteria and bacterial polysaccharides including Glu, LPS and PGN. In the presence of Ca2+, rLvCrustinVI showed a strong agglutination effect on V. parahaemolyticus and could significantly enhance the phagocytic ability of shrimp hemocytes against V. parahaemolyticus. In conclusion, LvCrustinVI played important roles as antimicrobial peptide and opsonin in the innate immune defense of L. vannamei. The study enriched our understanding of the functional activity of Crustin and provides an important basis for the development and utilization of antimicrobial peptides.

The identification of a serpin with immune defense role in oriental river prawn Macrobrachium nipponense

Serpins are a protein superfamily of serine protease inhibitors. One of their functions is to participate in immune responses by inhibiting the activation of prophenoloxidase. To elucidate the immune role of serpin in Macrobrachium nipponense, a serpin gene (Mnserpin) was cloned from M. nipponense in this study. Mnserpin protein has an N-terminal signal peptide and a serpin domain that contains a hinge region, a signature sequence of serpin and a P1(arginine)-P1’ scissile bond, and evolutionally closely related to the crustacean serpins. Mnserpin highly expressed in the hepatopancreas and gill. Mnserpin expression increased first and then decreased after Vibrio parahaemolyticus and Aeromonas hydrophila infection, and was knocked down by dsMnserpin injection with a maximum knockdown efficiency of 92 %. Mnserpin knockdown increased the expression of the clip domain serine protease and prophenoloxidase genes and phenoloxidase activity of M. nipponense as well as its mortality rate after V. parahaemolyticus and A. hydrophila infection. The recombinant Mnserpin (rMnserpin) showed bacteria-binding and bacteriostatic activity in vitro. Moreover, rMnserpin injection decreased the bacterial number and the mortality rate of M. nipponense post V. parahaemolyticus and A. hydrophila infection. These results suggested that Mnserpin plays a major role in the innate immune response of M. nipponense.

Investigating the Impact of Varied Dietary Protein Levels on Litopenaeus vannamei: An Exploration of the Intestinal Microbiota and Transcriptome Responses

This study explored the effects of dietary protein levels on Litopenaeus vannamei with its intestinal microbiota and transcriptome responses. Previous studies on the effects of dietary protein levels on L. vannamei have focused on growth performance, antioxidant indices, and digestive enzyme activity, but few studies have been conducted at the microbiological and molecular levels. In this study, five isolipid experimental diets with protein levels of 32% (P32), 36% (P36), 40% (P40), 44% (P44), and 48% (P48) were used in an L. vannamei (0.63 ± 0.02 g) feeding trial for 56 days. At the end of the feeding trial, the growth performance, immunity, intestinal health, and transcriptional responses of L. vannamei were determined. This study demonstrated that higher protein levels (P44) led to superior weight gain and growth rates for L. vannamei, with lower feed conversion ratios (FCR) observed in the P48 and P44 groups compared to the P32 and P36 groups (p ≤ 0.05). The P44 and P48 groups also showed a notably higher protein efficiency ratio (PER) compared to others (p ≤ 0.05), and there was no significant difference between them. Upon Vibrio parahaemolyticus infection, the P48 group exhibited a significantly lower survival rate (SR) within 48 h, while during 72 h of white spot syndrome virus (WSSV) infection, the P44 group had a notably higher survival rate than the P32 group (p ≤ 0.05). Digestive enzyme activity and antioxidant levels in L. vannamei initially increased and then decreased as protein levels increased, usually peaking in the P40 or P44 groups. Lower dietary protein levels significantly reduced the relative abundance of beneficial bacteria and increased the relative abundance of pathogenic bacteria in the intestines of L. vannamei. Transcriptome sequencing analysis revealed that most differentially expressed genes (DEGs) were up-regulated and then down-regulated as dietary protein levels increased. Furthermore, KEGG pathway enrichment analysis indicated that several immune and metabolic pathways, including metabolic pathways, glutathione metabolism, cytochrome P450, and lysosome and pancreatic secretion, were significantly enriched. In summary, the optimal feed protein level for L. vannamei shrimp was 40–44%. Inappropriate feed protein levels reduced antioxidant levels and digestive enzyme activity and promoted pathogen settlement, deceasing factors in various metabolic pathways that respond to microorganisms through transcriptional regulation. This could lead to stunted growth in L. vannamei and compromise their immune function.

Molecular docking and dynamics simulation studies uncover the host-pathogen protein-protein interactions in Penaeus vannamei and Vibrio parahaemolyticus.

Shrimp aquaculture contributes significantly to global economic growth, and the whiteleg shrimp, Penaeus vannamei, is a leading species in this industry. However, Vibrio parahaemolyticus infection poses a major challenge in ensuring the success of P. vannamei aquaculture. Despite its significance in this industry, the biological knowledge of its pathogenesis remains unclear. Hence, this study was conducted to identify the interaction sites and binding affinity between several immune-related proteins of P. vannamei with V. parahaemolyticus proteins associated with virulence factors. Potential interaction sites and the binding affinity between host and pathogen proteins were identified using molecular docking and dynamics (MD) simulation. The P. vannamei-V. parahaemolyticus protein-protein interaction of Complex 1 (Ferritin-HrpE/YscL family type III secretion apparatus protein), Complex 2 (Protein kinase domain-containing protein-Chemotaxis CheY protein), and Complex 3 (GPCR-Chemotaxis CheY protein) was found to interact with -4319.76, -5271.39, and -4725.57 of the docked score and the formation of intermolecular bonds at several interacting residues. The docked scores of Complex 1, Complex 2, and Complex 3 were validated using MD simulation analysis, which revealed these complexes greatly contribute to the interactions between P. vannamei and V. parahaemolyticus proteins, with binding free energies of -22.50 kJ/mol, -30.20 kJ/mol, and -26.27 kJ/mol, respectively. This finding illustrates the capability of computational approaches to search for molecular binding sites between host and pathogen, which could increase the knowledge of Vibrio spp. infection on shrimps, which then can be used to assist in the development of effective treatment.

Tapping Chlorella vulgaris potential for enhanced growth, immunity, digestion, microbiota, and immunometabolism in Litopenaeus vannamei feeding across varied salinities

This study explored the use of Chlorella vulgaris (CHL) in Litopenaeus vannamei under varying salinity conditions. Juvenile L. vannamei (initial weight 0.38 ± 0.01 g) were fed experimental diets for 8 weeks at different salinity levels: low (15‰), moderate (30‰), and high (45‰). The control diet contained 589 g/kg fishmeal (FM) as the sole protein source, while experimental diets included 150 g/kg FM and 492 g/kg CHL as protein sources. Results revealed that shrimp fed with CHL showed a robust survival rate even at higher salinities. Following a Vibrio parahaemolyticus infection challenge, shrimp fed with CHL exhibited higher survival rates than those fed with FM at equivalent salinities. Enzyme activity and gene expression analyses indicated that CHL enhanced immune response and digestion in L. vannamei compared to the FM, even under similar salinity conditions. Additionally, shrimp fed with CHL outperformed those fed with FM under varying salinity stress. Microbiota analysis revealed increased diversity and beneficial bacteria in the intestines of shrimp fed with CHL at the same salinity levels. Transcriptomic sequencing identified genes with differential expression (DEGs) related to immune and metabolic pathways. Furthermore, a combined analysis of microbiota and DEGs revealed that CHL also had a beneficial impact on the composition of the intestinal microbiota and controlled the expression of genes related to immune and metabolic pathways. In summary, CHL as a primary protein source improved survival rate, disease resistance, immune response, and digestion in L. vannamei, positively impacting intestinal microbiota and gene expression, and enhancing adaptability to salinity changes.

Comparative transcriptome analysis of hepatopancreas reveals the potential mechanism of shrimp resistant to Vibrio parahaemolyticus infection

Vibrio parahaemolyticus carrying a pathogenic plasmid (VPAHPND) is one of the main causative agents of acute hepatopancreatic necrosis disease (AHPND) in shrimp aquaculture. Knowledge about the mechanism of shrimp resistant to VPAHPND is very helpful for developing efficient strategy for breeding AHPND resistant shrimp. In order to learn the mechanism of shrimp resistant to AHPND, comparative transcriptome was applied to analyze the different expressions of genes in the hepatopancreas of shrimp from different families with different resistance to VPAHPND. Through comparative analysis on the hepatopancreas of shrimp from VPAHPND resistant family and susceptible family, we found that differentially expressed genes (DEGs) were mainly involved in immune and metabolic processes. Most of the immune-related genes among DEGs were highly expressed in the hepatopancreas of shrimp from resistant family, involved in recognition of pathogen-associated molecular patterns, phagocytosis and elimination of pathogens, maintenance of reactive oxygen species homeostasis and other immune processes etc. However, most metabolic-related genes were highly expressed in the hepatopancreas of shrimp from susceptible family, involved in metabolism of lipid, vitamin, cofactors, glucose, carbohydrate and serine. Interestingly, when we analyzed the expression of above DEGs in the shrimp after VPAHPND infection, we found that the most of identified immune-related genes remained at high expression levels in the hepatopancreas of shrimp from the VPAHPND resistant family, and most of the identified metabolic-related genes were still at high expression levels in the hepatopancreas of shrimp from the VPAHPND susceptible family. The data suggested that the differential expression of these immune-related and metabolic-related genes in hepatopancreas might contribute to the resistance variations of shrimp to VPAHPND. These results provided valuable information for understanding the resistant mechanism of shrimp to VPAHPND.

Response pattern of hemocyanin to Vibrio parahaemolyticus infection and its immune function in the swimming crab Portunus trituberculatus

Hemocyanin is a critical oxygen-transporting protein exhibiting multiple physiological functions, including protein storage and transportation, osmolarity regulation, molting, and immunomodulation in arthropods and mollusks. However, the immune function of hemocyanin in Portunus trituberculatus is rarely reported. Here, we identified ten subunit genes within the hemocyanin family from the P. trituberculatus genome. These genes exhibited conserved functional domains and copper ion binding sites. Building upon prior research, we specifically focused on investigating the immune functions of PtHc1 and PtHc2. Tissue expression analysis revealed that PtHc1 and PtHc2 were prominently expressed in the hepatopancreas and hemocytes. Upon infection with Vibrio parahaemolyticus, both PtHc1 and PtHc2 demonstrated a similar expression pattern, characterized by a gradual upregulation of expression levels in the hepatopancreas. While within the hemocytes, they exhibited a trend of initial downregulation followed by subsequent upregulation in expression. In addition, Recombinant hemocyanin was able to inhibit bacterial proliferation in a dose-dependent manner, with inhibition rates of 40 % and 39 % when the recombinant proteins of PtHc1 and PtHc2 reached 0.03 mg/mL, respectively. Besides, V. parahaemolyticus challenge resulted in a significant 20–23 % increase in mortality in P. trituberculatus following knockdown of PtHc1 and PtHc2. Overall, our study sheds light on the immune-related functions of PtHc1 and PtHc2 in P. trituberculatus, revealing their potential as key players in defending against pathogenic threats like V. parahaemolyticus. These results enriched the field of innate immunity in crustacean and providing a theoretical basis for disease resistance breeding.

The Yin Yang 1 of Penaeus vannamei regulates transcription of the small subunit hemocyanin gene during Vibrio parahaemolyticus infection

Hemocyanin is a respiratory protein, it is also a multifunctional immune molecule that plays a vital role against pathogen invasion in shrimp. However, the regulation of hemocyanin gene expression in shrimp hemocytes and the mechanisms involved during pathogen infection remains unclear. Here, we used DNA pull-down followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify the Yin Yang 1 transcription factor homolog in Penaeus vannamei (PvYY1) as a key factor that modulates transcription of the small subunit hemocyanin gene of P. vannamei (PvHMCs) in hemocytes during Vibrio parahaemolyticus AHPND (VPAHPND) infection. Bioinformatics analysis revealed that the core promoter region of PvHMCs contains two YY1 motifs. Mutational and oligoprecipitation analyses confirmed that PvYY1 could bind to the YY1 motifs in the PvHMCs core promoter region, while truncation of PvYY1 revealed that the N-terminal domain of PvYY1 is essential for the transactivation of PvHMCs core promoter. Besides, the REPO domain of PvYY1 could repress the activity of the PvHMCs core promoter. Overexpression of PvYY1 significantly activates the promoter activity of PvHMCs core promoter, while PvYY1 knockdown significantly decreases the expression level of PvHMCs in shrimp hemocytes and survival rate of shrimp upon infection with VPAHPND. Our present study provides new insights into the transcriptional regulation of PvHMCs by PvYY1 in shrimp hemocytes during bacteria (VPAHPND) infection.

Application of Fragmented Extracellular Self-DNA (esDNA) Concept as an Alternative Prophylactic Approach against Vibrio parahaemolyticus and Vibrio harveyi Infection in Brine Shrimp Artemia

The purpose of this study was to investigate species specific inhibitory effects of esDNA isolated from two conspecific organisms: Vibrio parahaemolyticus (VP) and Vibrio harveyi (VH), and to assess the functional role of esDNA to enhance the survival rate of Artemia sp. In an in vitro study, nine doses of Extracellular self-DNA of Vibrio parahaemolyticus (esDNAVP) and Vibrio harveyi (esDNAVH) were used as the target for the challenge test with the conspecific bacteria. In an in vivo study, the protective effect of esDNA was then tested in nauplii of the brine shrimp Artemia at various priming times and concentrations of esDNA under gnotobiotic conditions prior to challenge with VP and VH at the concentration of 5 × 105 CFU mL-1. The results from in vitro study showed that the use of esDNAVP at levels of 24.02 and 48.05 ng µl-1 and esDNAVH at concentrations of 13.33 and 26.67 ng µl-1 were able to inhibit the growth of the conspecific species when added to the culture medium at the concentration level of 5 × 105 CFU mL-1. The results from in vivo study showed that the use of 24.02; 48.05 and 72.07 ng µl-1 of esDNAVP as well as the use of 13.33; 26.67 and 40.00 ng µl-1 of esDNAVH inhibited the growth of VP and VH and enhanced the survival rate of Artemia sp compared to the control treatment (P&lt;0.05). Taken together, we confirmed that esDNA obtained from the extraction and random fragmentation from esDNAVP and esDNAVH, produces a species-specific inhibitory effect on the same species and can serve as a potential alternative strategy for disease control to deliver the functionality of esDNA to the fish and shrimp.

Protective effects of Chlorella vulgaris as a feed additive on growth performance, immunity, histopathology, and disease resistance against Vibrio parahaemolyticus in the Pacific white shrimp

The present study investigated the effect of Chlorella vulgaris on growth performance, feed consumption, body composition, and immune response of white shrimp (Litopenaeus vannamei) against Vibrio parahaemolyticus infection. Shrimps (4.00 ± 0.04 g) were divided into five groups (3 replicates/20 each) in 15 hapa (1 m3) and cultured for 56 days with five C. vulgaris experimented diets at five different concentrations (0, 15, 20, 25, and 30 g/kg feed). Growth performance, feed utilization, biomass, and body composition (protein, lipid, and ash) were analyzed and revealed significant increase (P < 0.05) in shrimp fed the high C. vulgaris diet. Additionally, the survival rate of shrimp in all experimental feeds was improved, but was not significant. Shrimp fed with C. vulgaris at different concentrations showed significantly (P < 0.05) higher antioxidant activity. The study showed that shrimp fed with a concentration of 30 g/kg C. vulgaris in the diet showed significantly (P < 0.05) highest disease resistance against the pathogen tested. Hence, dietary C. vulgaris might be used to improve growth performance, feed utilization, body composition, and immune biomarker responses, leading to disease resistance in cultured shrimp.

Gut bacterial consortium enriched in a biofloc system protects shrimp against Vibrio parahaemolyticus infection

BackgroundShrimp cultured in a biofloc system (BFS) have a lower disease incidence than those farmed in a water exchange system (WES). Although a number of studies have reported that the gut bacterial community induced by BFS is highly associated with shrimp disease resistance, the causal relationship remains unknown. Here, the promotive roles of gut bacterial community induced by BFS in pathogenic Vibrio infection resistance and its potential micro-ecological and physiological mechanisms were investigated by gut bacterial consortium transplantation and synthetic community (SynCom) construction.ResultsThe BFS induced a more stable and resistant gut bacterial community, and significantly enriched some beneficial bacterial taxa, such as Paracoccus, Ruegeria, Microbacterium, Demequina, and Tenacibaculum. Transplantation of a gut bacterial consortium from BFS shrimp (EnrichBFS) greatly enhanced the stability of the bacterial community and resistance against pathogenic V. parahaemolyticus infection in WES shrimp, while transplantation of a gut bacterial consortium from WES shrimp significantly disrupted the bacterial community and increased pathogen susceptibility in both WES and BFS shrimp. The addition of EnrichBFS in shrimp postlarvae also improved the pathogen resistance through increasing the relative abundances of beneficial bacterial taxa and stability of bacterial community. The corresponding strains of five beneficial bacterial taxa enriched in BFS shrimp were isolated to construct a SynComBFS. The addition of SynComBFS could not only suppress disease development, but also improve shrimp growth, boost the digestive and immune activities, and restore health in diseased shrimp. Furthermore, the strains of SynComBFS well colonized shrimp gut to maintain a high stability of bacterial community.ConclusionsOur study reveals an important role for native microbiota in protecting shrimp from bacterial pathogens and provides a micro-ecological regulation strategy towards the development of probiotics to ameliorate aquatic animal diseases.1NpdyYjfCEzGqNeY6CWHQHVideo