Potential use of chitosan nanoparticles for oral delivery of DNA vaccine in black seabream Acanthopagrus schlegelii Bleeker to protect from Vibrio parahaemolyticus

Chitosan nanogel aqueous treatment improved blood biochemicals, antioxidant capacity, immune response, immune-related gene expression and infection resistance of Nile tilapia

Candida albicans is a pathogenic yeast recently associated with diverse diseases in aquaculture. The present study investigated the efficacy of chitosan nanogel (CNG) in ameliorating effects of C. albicans on Nile tilapia (Oreochromis niloticus). Fish were randomly distributed into four groups (control, waterborne CNG at 75 μg/L, intraperitoneally challenged with C. albicans (1.8 × 107 CFU/mL), and waterborne CNG at 75 μg/L + C. albicans at 1.8 × 107 CFU/mL). Results showed that C. albicans infection reduced survival rate (57.5%) and caused marked clinical symptoms in fish among all infected groups. Substantial declines in immunological (complement 3, lysozyme, and immunoglobulin M), protein (total protein and non-albumin protein), and antioxidant (catalase, glutathione peroxidase, and superoxide dismutase) biochemical endpoints were exhibited, The C. albicans infected group also showed marked down-regulation in the expression of immune-related genes, including toll-like receptor 2 (TLR-2), transforming growth factor beta2, tumor necrosis factor alpha, interleukins (IL-1β, IL-6, and IL-10), and antiapoptotic gene (B-cell lymphoma, BCL-2). The expression of the apoptotic gene (Bcl-2 associated X protein, BAX) was up-regulated in fish challenged by C. albicans. The application of waterborne CNG to fish challenged with C. albicans infection improved fish survival (79.5%) and all other measured parameters. The main finding of this work was that CNG is a nanotechnology with potential for preventing degraded health status by C. albicans infection in tilapia, and thus has promise as an intervention in aquaculture settings.

An Introduction to Relevant Immunology Principles with Respect to Oral Vaccines in Aquaculture

Vaccines continue to play an enormous role in the progression of aquaculture industries worldwide. Though preventable diseases cause massive economic losses, injection-based vaccine delivery is cost-prohibitive or otherwise impractical for many producers. Most oral vaccines, which are much cheaper to administer, do not provide adequate protection relative to traditional injection or even immersion formulas. Research has focused on determining why there appears to be a lack of protection afforded by oral vaccines. Here, we review the basic immunological principles associated with oral vaccination before discussing the recent progress and current status of oral vaccine research. This knowledge is critical for the development and advancement of efficacious oral vaccines for the aquaculture industry.

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

Stabilizing vaccines via drying: Quality by design considerations

Pandemics and epidemics are continually challenging human beings' health and imposing major stresses on the societies particularly over the last few decades, when their frequency has increased significantly. Protecting humans from multiple diseases is best achieved through vaccination. However, vaccines thermal instability has always been a hurdle in their widespread application, especially in less developed countries. Furthermore, insufficient vaccine processing capacity is also a major challenge for global vaccination programs. Continuous drying of vaccine formulations is one of the potential solutions to these challenges. This review highlights the challenges on implementing the continuous drying techniques for drying vaccines. The conventional drying methods, emerging technologies and their adaptation by biopharmaceutical industry are investigated considering the patented technologies for drying of vaccines. Moreover, the current progress in applying Quality by Design (QbD) in each of the drying techniques considering the critical quality attributes (CQAs), critical process parameters (CPPs) are comprehensively reviewed. An expert advice is presented on the required actions to be taken within the biopharmaceutical industry to move towards continuous stabilization of vaccines in the realm of QbD.

Recent advances on chitosan as an adjuvant for vaccine delivery

Chitosan (CS) is a natural polymer derived from chitin that has wide applications in drugs, vaccines, and antigen delivery. The distinctive mucoadhesive, biocompatibility, biodegradable, and less toxic properties of chitosan compared to the currently used vaccine adjuvants made it a promising candidate for use as an adjuvant/carrier in vaccine delivery. In addition, chitosan exhibits intrinsic immunomodulating properties making it a suitable adjuvant in preparing vaccines delivery systems. Nanoparticles (NPs) of chitosan and its derivatives loaded with antigen have been shown to induce cellular and humoral responses. Versatility in the physicochemical properties of chitosan can provide an excellent opportunity to engineer antigen-specific adjuvant/delivery systems. This review discusses the recent advances of chitosan and its derivatives as adjuvants in vaccine deliveryand the published literature in the last fifteen years. The impact of physicochemical properties of chitosan on vaccine formulation has been described in detail. Applications of chitosan and its derivatives, their physicochemical properties, and mechanisms in enhancing immune responses have been discussed. Finally, challenges and future aspects of chitosan use has been pointed out.

A novel low-molecular-weight chitosan/gamma-polyglutamic acid polyplexes for nucleic acid delivery into zebrafish larvae

Many challenges, such as virus infection, extreme weather and long cultivation periods, during the development of fish larvae have been observed, especially in aquaculture. Gene delivery is a useful method to express functional genes to defend against these challengers. However, the methods for fish larvae are insufficient. In our earlier report, low-molecular-weight chitosan (LMWCS) showed a strong positive charge and may be useful for polyplex formulation. Herein, we present a simple self-assembly of LMWCS polyplexes (LMWCSrNPs) for gene delivery into zebrafish larvae. Different weight ratios of LMWCS/gamma-polyglutamic acid (γ-PGA)/plasmid DNA were analyzed by gel mobility assay. Delivery efficiency determined by green fluorescent protein (GFP) expression in zebrafish liver (ZFL) cells showed that delivery efficiency at a weight ratio of 20:8:1 was higher than others. Zeta potential and transmission electron microscopy (TEM) analysis showed that the round shape of the particle size varied. In our earlier reports, IRF9S2C could induce interferon-stimulated gene (ISG) expression to induce innate immunity in zebrafish and pufferfish. Further delivery of pcDNA3-IRF9S2C-HA plasmid DNA into ZFL cells and zebrafish larvae by LMWCSrNP successfully induced ISG expression. Collectively, LMWCSrNP could be a novel gene delivery system for zebrafish larvae and might be used to improve applications in aquaculture.

Protection of Teleost Fish against Infectious Diseases through Oral Administration of Vaccines: Update 2021

Immersion and intraperitoneal injection are the two most common methods used for the vaccination of fish. Because both methods require that fish are handled and thereby stressed, oral administration of vaccines as feed supplements is desirable. In addition, in terms of revaccination (boosting) of adult fish held in net pens, oral administration of vaccines is probably the only feasible method to obtain proper protection against diseases over long periods of time. Oral vaccination is considered a suitable method for mass immunization of large and stress-sensitive fish populations. Moreover, oral vaccines may preferably induce mucosal immunity, which is especially important to fish. Experimental oral vaccine formulations include both non-encapsulated and encapsulated antigens, viruses and bacteria. To develop an effective oral vaccine, the desired antigens must be protected against the harsh environments in the stomach and gut so they can remain intact when they reach the lower gut/intestine where they normally are absorbed and transported to immune cells. The most commonly used encapsulation method is the use of alginate microspheres that can effectively deliver vaccines to the intestine without degradation. Other encapsulation methods include chitosan encapsulation, poly D,L-lactide-co-glycolic acid and liposome encapsulation. Only a few commercial oral vaccines are available on the market, including those against infectious pancreatic necrosis virus (IPNV), Spring viremia carp virus (SVCV), infectious salmon anaemia virus (ISAV) and Piscirickettsia salmonis. This review highlights recent developments of oral vaccination in teleost fish.

Immunostimulatory effect of chitosan and quaternary chitosan: A review of potential vaccine adjuvants

Vaccines have always been the most effective preventive treatment. Advancements in the field of vaccine is inseparable from adjuvants. Adjuvants are substances added to vaccines to enhance immunogenicity and induce a stronger immune response. Chitosan fascinated considerable attention as vaccine adjuvant due to its unique physicochemical and biological properties. Many studies have shown that chitosan and its derivatives can effectively activate antigen-presenting cells and induce cytokine stimulation to produce an effective immune response and promote the balance of Th1/Th2 response. Among many derivatives, the quaternized chitosan performs better. This review presents the main factors affecting the adjuvant performance of chitosan and quaternized chitosan firstly. Then, we introduced not only the immune response they may cause, but also their metabolic research in detail. Furthermore, their future prospects are forecasted. Overall, chitosan and quaternized chitosan are both promising adjuvant materials, and quaternized chitosan shows greater potential.

Advantages and prospective challenges of nanotechnology applications in fish cultures: a comparative review

Applications of nanotechnology in fish cultures have participated in getting over various difficulties that hinder fish productivity. They can achieve growth performance after adding some important minerals and vitamins in the form of nano-feed supplements like selenium, zinc, iron, and vitamin C. Also, they have an important role in reproduction, and fish medicine as antimicrobial, drug delivery, nano-vaccination, and rapid disease diagnosis. Moreover, their roles in water remediation and purification, and fish packaging are documented. On the other hand, some nanoparticles exhibit toxic effects on living organisms, which return to their tiny size, high reactivity, and permeability. They can alter many physiological functions and cause cytotoxicity, DNA damage, and histopathological changes. Also, nanotechnology applications cause new secondary pollutants to be introduced into the environment that can negatively affect fish health and the surrounding living organisms. So, in spite of the promising applications of nanotechnology to fulfill high growth performance and pathogen-free fish, there are a lot of debates about the potential toxicity of nanomaterials, their reactivity with the surrounding environment, and bioaccumulation. The present review aims to elucidate and discuss various advantages and challenges of nanotechnology applications in fish cultures. Also, it points to green nanotechnology as a promising alternative to chemical ones.

Gut immunity in European sea bass (Dicentrarchus labrax): a review

In this review, we summarize and discuss the trends and supporting findings in scientific literature on the gut mucosa immune role in European sea bass (Dicentrarchus labrax L.). Overall, the purpose is to provide an updated overview of the gastrointestinal tract functional regionalization and defence barriers. A description of the available information regarding immune cells found in two immunologically-relevant intestinal compartments, namely epithelium and lamina propria, is provided. Attention has been also paid to mucosal immunoglobulins and to the latest research investigating gut microbiota and dietary manipulation impacts. Finally, we review oral vaccination strategies, as a safe method for sea bass vaccine delivery.

Chitosan-Based Drug Delivery System: Applications in Fish Biotechnology

Chitosan is increasingly used for safe nucleic acid delivery in gene therapy studies, due to well-known properties such as bioadhesion, low toxicity, biodegradability and biocompatibility. Furthermore, chitosan derivatization can be easily performed to improve the solubility and stability of chitosan-nucleic acid polyplexes, and enhance efficient target cell drug delivery, cell uptake, intracellular endosomal escape, unpacking and nuclear import of expression plasmids. As in other fields, chitosan is a promising drug delivery vector with great potential for the fish farming industry. This review highlights state-of-the-art assays using chitosan-based methodologies for delivering nucleic acids into cells, and focuses attention on recent advances in chitosan-mediated gene delivery for fish biotechnology applications. The efficiency of chitosan for gene therapy studies in fish biotechnology is discussed in fields such as fish vaccination against bacterial and viral infection, control of gonadal development and gene overexpression and silencing for overcoming metabolic limitations, such as dependence on protein-rich diets and the low glucose tolerance of farmed fish. Finally, challenges and perspectives on the future developments of chitosan-based gene delivery in fish are also discussed.

Comparative immunohistological study on using capsaicin, piperine, and okadaic acid for the transepithelial passage of the inactivated viral and bacterial vaccines in fish

The practical difficulty of parenteral application of fish vaccines against devastating fish diseases diverted the interest toward oral vaccination. Search for effective methods to enhance the oral uptake of viral and bacterial vaccines is continuing. The current research focus on a new role of mucosal fish vaccine adjuvants inducing the antigen uptake by enhancing vascularity or increasing intestinal permeability. Some inflammatory substances cause reversible pathology to the intestinal epithelium, which could be employed for the transepithelial passage of vaccine particles. The natural inflammatory substances used were capsaicin, piperine, and okadaic acid as 1 mg, 2 mg, and 1 μg/fish, respectively. Two inactivated vaccines were used as antigens to test the effect of these inflammatory substances in two different fish hosts. Tested vaccines were inactivated redspotted grouper nervous necrosis virus vaccine in sevenband grouper (Epinephelus septemfasciatus) and inactivated Edwardsiella tarda vaccine in red sea bream (Pagrus major) fish models. The inflammatory substances and each vaccine were anally intubated to fish. Capsaicin proved to be effectively aiding the transepithelial passage of vaccine particles more than piperine, while okadaic acid had no detectable effect.

An overview of biodegradable nanomaterials and applications in vaccines

Vaccination is the most cost-effective and sustainable way to prevent and eliminate infectious diseases. Compared with traditional vaccines, novel vaccines have better stability, longer duration and require less antigen usage. In addition, novel vaccines have better immune effects and significantly less toxic side effects. However, both novel vaccines and traditional vaccines require carrier molecules or adjuvants to produce an optimal immune response. There is an increasing demand for vaccine adjuvants and delivery systems that can induce stronger immune response whilst reducing production cost and the dose of vaccine. In recent years, nanotechnology has played an important role in the development of novel vaccine adjuvants and nano-delivery systems. Biodegradable materials have also received a lot of attention in medical science because they have excellent biocompatibility, biodegradability and low toxicity, which can protect antigens from degradation, increase antigen stability and provide slow release; resulting in enhanced immunogenicity. Therefore, biodegradable nanoparticles have attracted much attention in the formulation of vaccines. In this review, we outline some key features of biodegradable nanomaterials in the developing safer and more effective vaccines. The properties, structural characteristics, advantages and disadvantage of the biodegradable nanomaterials will be systematically reviewed. Additionally, applications, research progress and future prospects of biodegradable nanomaterials are discussed. This review will be help in future research work directed at developing biodegradable vaccine adjuvants or delivery carriers.

Evaluation of biofilm of Vibrio anguillarum for oral vaccination of Asian seabass, Lates calcarifer (BLOCH, 1790)

The present study evaluated the biofilm (BF) of Vibrio anguillarum for oral vaccination of Asian seabass, Lates calcarifer. An 80-day experiment was carried out in circular fiber-reinforced plastic (FRP) tanks using free cell (FC) and BF of Vibrio anguillarum with triplicate in each. Heat-inactivated FC and BF cells at 10⁷, 10¹⁰ and 10¹³ CFU/g fish/d were fed to fish for 20 days, agglutination antibody titer estimated at each 10 days interval up to 60-day post vaccination. As compared to FC and control there was a significant increase in agglutinating antibody titer in the biofilm vaccinated fishes. Among the 3 doses, BF at 10¹⁰ cfu/g fish/d was considered the ideal dose for vaccination. Relative percentage survival (RPS) was higher in biofilm vaccinated fish (85.4%) compared to that with free cells (27.0%). The study demonstrated the better performance of V. anguillarum biofilm oral vaccine compared that with free cell vaccine in L. calcarifer. The study further supports better performance of biofilm vaccine model with one more bacterial pathogen in a high carnivore fish.

Molecular and antimicrobial characterization of a group G anti-lipopolysaccharide factor (ALF) from Penaeus monodon

Anti-lipopolysaccharide factors (ALFs) are important host-defense molecules of crustaceans. They all contain a lipopolysaccharide-binding domain (LBD) and some ALFs exhibit strong antimicrobial activity. In this research, a Group G ALF from Penaeus monodon (ALFPm11) was studied. It is an anionic peptide specifically having a cationic and highly amphipathic LBD, with five positively charged residues separated by aromatic residues. It was abundantly expressed in the hepatopancreas of P. monodon normally but the expression level in other tissues was relatively low or undetectable. However, in the shrimps challenged by Vibrio, expression of ALFPm11 could be detected in all tissues. Chemically synthesized ALFPm11-LBD displayed high inhibitory activity (minimum inhibition concentration≤ 4 μM) against various bacteria, e.g. Exiguobacterium sp. L33, Bacillus sp. T2, and Acinetobacter sp. L32. It also displayed apparent activity in the agar well diffusion assay. Furthermore, it could efficiently induce agglutination of both Gram-positive and Gram-negative bacteria and cause significant membrane permeabilization of the bacteria. As a comparative study, ALFPm11-LBD showed a better or equal antimicrobial function to ALFPm3-LBD which was reported to possess strong antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. Thus, this research found a new effective ALF in P. monodon and demonstrated its antimicrobial mechanism, suggesting its potential applications in the future.

Recent progress in biomedical applications of chitosan and its nanocomposites in aquaculture: A review

Chitosan nanoparticles (CSNPs) are the nanostructures of chitosan biopolymer which is derived from chitin polysaccharide, the main component of crustacean shells. Chitosan is a biocompatible, nontoxic and biodegradable polymer soluble in acidic solutions and easily excreted from kidneys. It is widely used in medical and pharmaceutical applications including artificial matrices for tissue engineering, drug transport, targeted drug delivery and protein or gene delivery. The antimicrobial activities of chitosan and CSNPS against different bacterial, fungal and viral pathogens made them valuable for several biological applications including food preservation purposes. In addition, they have immunomodulatory effects on fish and crustaceans providing direct positive impact on aquaculture and fish farming industry. Sustained release of some bioactive ingredients such as hormones, vitamins, nutrients and antioxidants has improved the biological activities of fish. Furthermore, CSNPs have recently been employed to diagnose fish diseases. In this review, we present the medical and biological applications of chitosan and CSNPs on aquatics to provide an update on recent advances and the potential for further advanced applications for aquaculture in the future.

Combined vaccines for prophylaxis of infectious conditions

In recent years, the application of vaccines shows limitations, including the high number of vaccine administrations and the fear of safety and effectiveness. In this regard, advanced vaccine products have been developed, like the combined vaccines, or are under development, such as nucleic acid vaccines (DNA and RNA), polymer-based vaccines, etc. Moreover, the possible use of traditional, like aluminium hydroxide and aluminium phosphate, or innovative adjuvants, like monophosphoryl lipid A, polysaccharides and nanoparticulate system, may further increase vaccine effectiveness. This review article focuses on the combined vaccines, which, especially when they are associated with adjuvants, reduce the dosing frequency, and prolong the duration of action, thus providing better vaccine coverage. Marketed preparations, like Typhim Vi, Peda typh and Boostrix showed better vaccine coverage for diseases like typhoid, tetanus, diphtheria and acellular pertussis. The future aspect for the development of combined vaccines will protect not only against infectious diseases but likely even against various infectious conditions, like pneumonia, meningococcal infection and respiratory syncytial virus infection.

Characterization of a group D anti-lipopolysaccharide factor (ALF) involved in anti-Vibrio response in Penaeus monodon

Antimicrobial peptides (AMPs) are an essential component of innate immunity of invertebrates. Anti-lipopolysaccharide factor (ALF), as a main type of AMPs in crustaceans, attends in the disease prevention in general. In this research, a novel Group D ALF was identified and characterized from Penaeus monodon, named PenmonALF8. It was an anionic peptide, with both the full-length peptide and lipopolysaccharide binding domain (LBD) a low isoelectric point. PenmonALF8, composed of a signal peptide of 26 amino acids and a mature peptide of 98 amino acids, probably contained three alpha helixes and four beta sheets. Moreover, PenmonALF8 was detected in all tested tissues of P. monodon, and the expression level in hemocyte and intestine was relatively high. When challenged by Vibrio parahaemolyticus, PenmonALF8 showed 30-100 times higher expression level in all the tissues except in hemocyte and intestine, indicating that PenmonALF8 played a very important role in the immune response of P. monodon. By fusing to a SUMO protein, PenmonALF8 was successfully over-expressed in E. coli and purified by affinity chromatography. Additionally, the reconstituted PenmonALF8 and its LBD region displayed modest antimicrobial activity. This is the first research about the Group D ALF in P. monodon, which provides more information for humoral immunity study of shrimps.

The preparation and antibacterial effect of egg yolk immunoglobulin (IgY) against the outer membrane proteins of Vibrio parahaemolyticus

BACKGROUND

Vibrio parahaemolyticus causes not only various diseases in aquaculture animals but also seafood-borne illness in humans. Outer membrane proteins (OMPs) are species-specific proteins found in bilayer membranes of gram-negative bacteria. Egg yolk immunoglobulin (IgY) has been reported to serve as oral administration of antibodies against bacteria and virus.

RESULTS

The present research extracted and identified OMPs from V. parahaemolyticus, and then the extracted OMPs were used to immunize hens to obtain specific IgY. The efficacy of IgY against V. parahaemolyticus were investigated in vitro and in vivo. The specific IgY effectively inhibited the growth of V. parahaemolyticus in liquid medium rather than Escherichia coli and Staphylococcus aureus. Specific IgY antibodies were incorporated into extruded food pellets and fed to bacteria-challenged white pacific shrimp to observe the anti-bacterial effect in vivo. The bacterial loads in muscles of V. parahaemolyticus infected shrimp fed with specific IgY-included diets were significantly fewer than those fed with non-specific IgY-included diets. The superoxide dismutase activities in muscles of infected shrimp fed with specific IgY-included diets were significantly higher than the control group.

CONCLUSION

The results suggested that the specific IgY effectively inhibited the growth of V. parahaemolyticus and introduced passive immunity to shrimp. © 2018 Society of Chemical Industry.

Pichia pastoris yeast as a vehicle for oral vaccination of larval and adult teleosts

Oral vaccination is of major interest because it can be used for mass vaccination of fish of various size and age. Given that their administration is relatively easy and stress-free, oral vaccines have both economic and animal welfare benefits. Yet, mostly due to their limited efficacy, only very few oral vaccines are available to aquaculture industry. Here we present a method for oral vaccine delivery based on the yeast Pichia pastoris. We could express a model antigen, green fluorescent protein (GFP), in this yeast and subsequently show delivery of the GFP protein to the intestine of juvenile flounder or adult carp and trout. We tested this approach in several commercially-relevant fish species, from juvenile to adult stage. To test the oral delivery of antigen to larval fish, the GFP-expressing Pichia pastoris was first fed to planktonic crustacean Daphnia or rotifers that served as 'bioencapsulation vehicles' and afterwards, fed to flounder larvae. Again, we could show delivery of intact GFP protein to the intestine. In rainbow trout, the orally-administered GFP-expressing yeast elicited a rapid local innate immune response in the intestine and a subsequent systemic response in the spleen. Our results show that Pichia pastoris is a good vehicle for oral antigen delivery and that it can be used in non-encapsulated form for older fish or in bioencapsulated form for larval fish. We discuss the immunomodulatory properties of the yeast itself, and its potential to enhance local immune responses and act as an adjuvant.

Liver transcriptome analysis of the Sparus macrocephlus in response to Vibrio parahaemolyticus infection

The black seabream (Sparus macrocephlus) is an economically pivotal aquaculture species cultured in China and Southeast Asian countries. To understand the molecular immune mechanisms underlying the response to Vibrio parahaemolyticus, a comparative gene transcription analysis were performed with utilized fresh livers of V. parahaemolyticus-immunized Sparus macrocephlus with a control group through RNA-Seq technology. A total of 256663 contigs were obtained after excluded the low-quality sequences and assembly. The average length of contigs collected from this research is 1066.93 bp. Furthermore, blast analysis indicates 30747 contigs were annotated based on homology with matches in the NT, NR, gene, and string databases. A gene ontology analysis was employed to classify 21598 genes according to three major functional categories: molecular function, cellular component, and biological process. A total of 14470 genes were discovered in 303 KEGG pathways. RSEM and EdgeR were introduced to estimate 3841 genes significantly different expressed (False Discovery Rate<0.001) which includes 4072 up-regulated genes and 3771 down-regulated genes. A significant enrichment analysis of these differentially expressed genes and isogenes were conducted to reveal the major immune-related pathways which refer to the toll-like receptor, complement, coagulation cascades, and chemokine signaling pathways. In addition, 92175 potential simple sequence repeats (SSRs) and 121912 candidate single nucleotide polymorphisms (SNPs) were detected and identified sequencely in the Sparus macrocephlus liver transcriptome. This research characterized a gene expression pattern for normal and the V. parahaemolyticus -immunized Sparus macrocephlus for the first time and not only sheds new light on the molecular mechanisms underlying the host-V. parahaemolyticus interaction but contribute to facilitate future studies on Sparus macrocephlus gene expression and functional genomics.

Nanoparticle mucoadhesive system as a new tool for fish immune system modulation

Recently, chitosan-based nanoparticles with mucoadhesive properties emerged as a strategy for mucosal drug release. This study aimed to characterize the interaction of mucoadhesive system chitosancoated PLGA nanoparticles (NPMA) with fish external mucus. NP suspensions with fluorescent probe were prepared and characterized by size, polydispersity, zeta potential and pH measures. In post-exposure fish were observed an increase in fluorescence imaging over time and it was significantly influenced by NPMA concentration. We also observed the main predominance the fluorescence in the spleen, followed by liver, gill and other tissues. The use of mucoadhesive nanocarriers becomes an alternative for administration of drugs and immunomodulators in immersion systems since the nanosystem can adhere to the mucosal surface of the fish with little residual effect in the water.

Polysaccharides as vaccine adjuvants

Adjuvant is a substance added to vaccine to improve the immunogenicity of antigens, and it can induce stronger immune responses and reduce the dosage and production cost of vaccine in populations responding poorly to vaccination. Adjuvants in development or in use mainly include aluminum salts, oil emulsions, saponins, immune-stimulating complexes, liposomes, microparticles, nonionic block copolymers, polysaccharides, cytokines and bacterial derivatives. Polysaccharide adjuvants have attracted much attention in the preparation of nano vaccines and nano drugs because natural polysaccharides have the characteristics of intrinsic immunomodulating, biocompatibility, biodegradability, low toxicity and safety. Moreover, it has been proved that a variety of natural polysaccharides possess better immune promoting effects, and they can enhance the effects of humoral, cellular and mucosal immunities. In the present study, we systematically reviewed the recent studies on polysaccharides with vaccine adjuvant activities, including chitosan-based nanoparticles (NPs), glucan, mannose, inulin polysaccharide and Chinese medicinal herb polysaccharide. The application and future perspectives of polysaccharides as adjuvants were also discussed. These findings lay a foundation for the further development of polysaccharide adjuvants. Collectively, more and more polysaccharide adjuvants will be developed and widely used in clinical practice with more in-depth investigations of polysaccharide adjuvants.

EmPis-1L, an Effective Antimicrobial Peptide Against the Antibiotic-Resistant VBNC State Cells of Pathogenic Bacteria

The antibiotic-resistant viable but non-culturable (VBNC) pathogenic bacteria are considered as a new threat to public health. Antimicrobial peptides (AMPs), possessing bactericidal effects in a rapid membrane attacking mode, are supposed to be effective against bacteria entering the VBNC state. In the current study, the activity of grouper AMP piscidin killing the VBNC state cells of pathogenic bacteria Escherichia coli O157, Staphylococcus aureus, and Vibrio parahaemolyticus OS4 was studied. After entering the VBNC state, cells of E. coli O157, S. aureus, and V. parahaemolyticus OS4 developed resistance to the antibiotics Ampicillin and Kanamycin. Rather than truncated form of Malabar grouper piscidin 1 (EmPis-1S), full-length Malabar grouper piscidin 1 (EmPis-1L) showed strong activity to kill the above VBNC bacteria. The VBNC state cells (1 × 10⁵ CFU/mL) of the three species of bacteria could be totally lysed by 10 μmol/L of EmPis-1L in 1 h. The VBNC state cells of S. aureus were most susceptible to EmPis-1L, which killed the cells by 100% in 30 min at the low concentration of 2.0 μmol/L. In addition, EmPis-1L at the concentration of no more than 10 μmol/L showed no observed toxicity to human lung carcinoma epithelial cells (A549) and mouse neuroblastoma cells (N2a). Accordingly, EmPis-1L could be a promisingly safe and efficient agent for eliminating the traditional antibiotic-resistant VBNC state cells of pathogenic bacteria, E. coli, S. aureus, and V. parahaemolyticus.

Intracellular Bacterial Infections: A Challenge for Developing Cellular Mediated Immunity Vaccines for Farmed Fish

Aquaculture is one of the most rapidly expanding farming systems in the world. Its rapid expansion has brought with it several pathogens infecting different fish species. As a result, there has been a corresponding expansion in vaccine development to cope with the increasing number of infectious diseases in aquaculture. The success of vaccine development for bacterial diseases in aquaculture is largely attributed to empirical vaccine designs based on inactivation of whole cell (WCI) bacteria vaccines. However, an upcoming challenge in vaccine design is the increase of intracellular bacterial pathogens that are not responsive to WCI vaccines. Intracellular bacterial vaccines evoke cellular mediated immune (CMI) responses that “kill” and eliminate infected cells, unlike WCI vaccines that induce humoral immune responses whose protective mechanism is neutralization of extracellular replicating pathogens by antibodies. In this synopsis, I provide an overview of the intracellular bacterial pathogens infecting different fish species in aquaculture, outlining their mechanisms of invasion, replication, and survival intracellularly based on existing data. I also bring into perspective the current state of CMI understanding in fish together with its potential application in vaccine development. Further, I highlight the immunological pitfalls that have derailed our ability to produce protective vaccines against intracellular pathogens for finfish. Overall, the synopsis put forth herein advocates for a shift in vaccine design to include CMI-based vaccines against intracellular pathogens currently adversely affecting the aquaculture industry.

Assessment of DNA Damage During Gene Delivery in Freshwater Prawn by Chitosan Reduced Gold Nanoparticles

The increasing application of nanoparticles both in industries and in agricultural fields has led to its accumulation in the aquatic ecosystem through water run-off. Insights into the validity of safer nanoparticles such as gold and chitosan are fairly established. However, its effect on aquatic invertebrates has been less studied. The present study was aimed to study effects of chitosan reduced gold nanoparticles (CRGNPs) during green fluorescent protein (GFP) encoding plasmid delivery in giant freshwater prawn, macrobrachium rosenbergii. The mean particle size and zeta potential CRGNPs was 33.7 nm and 24.79 mV respectively. Prawn juveniles were exposed to nanoparticles concentrations (10 µg/L, 20 µg/L) of CRGNPs by immersion treatment for a period of 36 hours. GFP was ubiquitously expressed in muscle tissues of prawns. The comet assay indicated dose dependent genotoxicity of CRGNPs in gill, pleopod and muscle tissues which was in conformity with its bioaccumulation pattern in vivo. The highest bioaccumulation of CRGNPs was found in Gills, followed by pleopods and least in muscles. Hence, the toxicological potential of CRGNPs to the environment cannot be denied and demands more research on the particular aspect. The doses standardized in the present study would be helpful in safer nano-gene delivery in aquatic invertebrates and development of transgenics employing less cost.

Identification and characterization of a novel defensin from Asian green mussel Perna viridis

Defensin is one of the most diversified groups of antimicrobial peptides in invertebrate. In the present study, a novel defensin member referred as Pv-Def was identified and characterized from Asian green mussel Perna viridis. Using in silico survey of several EST databases released from diverse tissues of P. viridis, a single peptide referred as Pv-Def was predicted as defensin homologue with Mytilus counterparts. Further analysis on gene structure revealed that Pv-Def was 1001 nt in length and consisted of 3 exons and 2 introns. The precursor of Pv-Def was composed of a signal peptide of 19 amino acids and a mature peptide of 45 amino acids. The mature Pv-Def peptide contains 6 cysteines which formed 3 disulfide bonds at ²⁷C₁- ⁵⁴C₄, ⁴⁰C₂- ⁶⁰C₅ and ⁴⁴C₃- ⁶²C₆. Like most of the defensin family members, mature Pv-Def peptide included an alpha helix and 2 beta strands. Pv-Def showed significantly tissue-specific expression pattern, while highest transcription level was observed in hepatopancreas, which was about 900 folds to that in hemocytes. Moreover, the expression of Pv-Def mRNA in hemocytes was significantly and accurately up-regulated at different time intervals by Vibrio parahaemolyticus challenge. Interestingly, phylogenetic analysis suggested that the Pv-Def possesses closest relationships with arthropods counterparts rather than other mollusk defensins. To our knowledge, this is the first time that a defensin member was reported in Asian green mussel P. viridis.

Seafood spoilage microbiota and associated volatile organic compounds at different storage temperatures and packaging conditions

Seafood comprising of both vertebrate and invertebrate aquatic organisms are nutritious, rich in omega-3 fatty acids, essential vitamins, proteins, minerals and form part of healthy diet. However, despite the health and nutritional benefits, seafood is highly perishable. Spoilage of seafood could be as a result of microbial activity, autolysis or chemical oxidation. Microbial activity constitutes more spoilage than others. Spoilage bacteria are commonly Gram negative and produce off odours and flavours in seafood as a result of their metabolic activities. Storage temperature, handling and packaging conditions affect microbial growth and thus the shelf-life of seafood. Due to the complexity of the microbial communities in seafood, culture dependent methods of detection may not be useful, hence the need for culture independent methods are necessary to understand the diversity of microbiota and spoilage process. Similarly, the volatile organic compounds released by spoilage bacteria are not fully understood in some seafood. This review therefore highlights current knowledge and understanding of seafood spoilage microbiota, volatile organic compounds, effects of storage temperature and packaging conditions on quality of seafood.

Polymer-Based Nanomaterials and Applications for Vaccines and Drugs

Nanotechnology plays a significant role in drug development. As carriers, polymeric nanoparticles can deliver vaccine antigens, proteins, and drugs to the desired site of action. Polymeric nanoparticles with lower cytotoxicity can protect the delivered antigens or drugs from degradation under unfavorable conditions via a mucosal administration route; further, the uptake of nanoparticles by antigen-presenting cells can increase and induce potent immune responses. Additionally, nanomaterials are widely used in vaccine delivery systems because nanomaterials can make the vaccine antigen long-acting. This review focuses on some biodegradable polymer materials such as natural polymeric nanomaterials, chemically synthesized polymer materials, and biosynthesized polymeric materials, and points out the advantages and the direction of research on degradable polymeric materials. The application and future perspectives of polymeric materials as delivery carriers and vaccine adjuvants in the field of drugs and vaccines are presented. With the increase of knowledge and fundamental understandings of polymer-based nanomaterials, means of integrating some other attractive properties, such as slow release, target delivery, and alternative administration methods and delivery pathways are feasible. Polymer-based nanomaterials have great potential for the development of novel vaccines and drug systems for certain needs, including single-dose and needle-free deliveries of vaccine antigens and drugs in the future.

Enhancing Mucosal Immune Response of Newcastle Disease Virus DNA Vaccine Using N-2-Hydroxypropyl Trimethylammonium Chloride Chitosan and N,O-Carboxymethyl Chitosan Nanoparticles as Delivery Carrier

Because mucosal sites are the entry ports of pathogens, immunization via mucosal routes can extremely enhance the immunity. To elevate the potential of N-2-hydroxypropyl trimethylammonium chloride chitosan (N-2-HACC) and N,O-carboxymethyl chitosan (CMC) nanoparticles as a mucosal immune delivery carrier for DNA vaccines, we prepared the NDV F gene plasmid DNA with C3d6 molecular adjuvant (pVAX I-F(o)-C3d6) encapsulated in the N-2-HACC-CMC nanoparticles (N-2-HACC-CMC/pFDNA-C3d6 NPs). The N-2-HACC-CMC/pFDNA-C3d6 NPs had regular spherical morphology and low toxicity with a mean diameter of 309.7 ± 6.52 nm, zeta potential of 49.9 ± 4.93 mV, encapsulation efficiency of 92.27 ± 1.48%, and loading capacity of 50.75 ± 1.35%. The N-2-HACC-CMC had high stability and safety. The pVAX I-F(o)-C3d6 could be sustainably released from the N-2-HACC-CMC/pFDNA-C3d6 NPs after an initial burst release. Immunization intranasally of chickens with N-2-HACC-CMC/pFDNA-C3d6 NPs not only produced higher anti-NDV IgG and sIgA antibody than chickens in other groups did, but also significantly stimulated lymphocyte proliferation and triggered higher the IL-2, IL-4, and IFN-γ levels. These findings indicated that the N-2-HACC-CMC could be used as an efficient delivery carrier for the mucosal immunity of Newcastle disease virus DNA vaccine. The work laid a basis for the quaternized chitosan nanoparticles as efficient mucosal immunity delivery carrier for DNA vaccines and had immense application promise and potential for vaccines and drugs.

Three new piscidins from orange-spotted grouper (Epinephelus coioides): Phylogeny, expression and functional characterization

The present study reports the identification, and characterization of three new putative piscidin paralogues, ecPis-2, ecPis-3 and ecPis-4, from orange-spotted grouper (Epinephelus coioides). The cDNA of the three piscidins with the 207, 216, and 231 nt open reading frame encoded respectively a 68-, 71-, and 76-amino acid preprotein consisting of the predicted signal peptide, and putative mature peptide and prodomain. The phylogenetic analysis indicated that multiple piscidin paralogues in one fish species are highly diversified, the analysis suggested that the piscidins should be a family belonging to the superfamily of ancient cationic, linear, and amphipathic host defence peptides widespread across invertebrate and vertebrate taxa comprising insect cecropins and ceratotoxins, and the amphibian dermaseptins. The synthetic putative mature peptides, ecPis-2S, ecPis-3S and ecPis-4S, had strong activities against bacterial and fungal species. EcPis-3S exhibited powerful activity against the infective stage of Cryptocaryon irritans, theronts. The full length ecPis-2 and ecPis-4 by removal of signal peptide, ecPis-2L and ecPis-4L respectively, had potency against bacterial, fungal and parasitic species. The peptide ecPis-2S was proved to exist in spleen of orange-spotted grouper by HPLC followed by ESI-LCMS analysis. Basal transcriptions of ecPis-2, ecPis-3 and ecPis-4 were detected not only in the potential sites of pathogen entry such as gills, skin and intestine, but also in tissues such as head kidney, trunk kidney, blood cells, and spleen with highly abundant immune cells, however different paralogues expressed constitutively with different levels in the tissues. In addition, the expression of ecPis-2, ecPis-3 and ecPis-4 was upregulated in orange-spotted grouper challenged by Vibrio Parahaemolyticus, in different tissues at different time point after bacteria injection. These results support ecPis-2, ecPis-3 and ecPis-4 being the important immune-related genes in orange-spotted grouper innate immune system and playing multifunctional and complementary roles following their structural and functional diversification, and expression pattern difference. Finally, this study facilitates the evaluation of ecPis-2S, 2L, ecPis-3S, and ecPis-4S, -4L as potential templates of therapeutic agents against pathogens.

Feeding of nano scale oats β-glucan enhances the host resistance against Edwardsiella tarda and protective immune modulation in zebrafish larvae

In this study, we prepared and characterized the oats origin of nano scale β-glucan (NBG) and investigated the immunomodulatory properties in zebrafish larvae. Newly prepared NBG (average particle size of 465 nm) was fully soluble in water. Zebrafish larvae survival rate was increased against pathogenic bacteria Edwardsiella tarda, when NBG was added to the water (500 μg/mL) compared to NBG non-exposed controls. Moreover, quantitative real time PCR (qRT-PCR) results showed up-regulation of immune functional genes including TNF-α, IL-1β, β-defensin, lysozyme, IL 10, IL 12 and C-Rel indicating higher survival rate could be due to stronger immunomodulatory function of NBG (500 μg/mL). Thus, non-toxic, water soluble and biodegradable NBG from oats could be considered as the potential immunostimulant for larval aquaculture.

An oral chitosan DNA vaccine against nodavirus improves transcription of cell-mediated cytotoxicity and interferon genes in the European sea bass juveniles gut and survival upon infection

Vaccines for fish need to be improved for the aquaculture sector, with DNA vaccines and the oral administration route providing the most promising improvements. In this study, we have created an oral chitosan-encapsulated DNA vaccine (CP-pNNV) for the nodavirus (NNV) in order to protect the very susceptible European sea bass (Dicentrarchus labrax). Our data show that the oral CP-pNNV vaccine failed to induce serum circulating or neutralizing specific antibodies (immunoglobulin M) or to up-regulate their gene expression in the posterior gut. However, the vaccine up-regulated the expression of genes related to the cell-mediated cytotoxicity (CMC; tcrb and cd8a) and the interferon pathway (IFN; ifn, mx and ifng). In addition, 3 months after vaccination, challenged fish showed a retarded onset of fish death and lower cumulative mortality with a relative survival of 45%. Thus, we created a chitosan-encapsulated DNA vaccine against NNV that is partly protective to European sea bass juveniles and up-regulates the transcription of genes related to CMC and IFN. However, further studies are needed to improve the anti-NNV vaccine and to understand its mechanisms.

Oral vaccination of fish: Lessons from humans and veterinary species

The limited number of oral vaccines currently approved for use in humans and veterinary species clearly illustrates that development of efficacious and safe oral vaccines has been a challenge not only for fish immunologists. The insufficient efficacy of oral vaccines is partly due to antigen breakdown in the harsh gastric environment, but also to the high tolerogenic gut environment and to inadequate vaccine design. In this review we discuss current approaches used to develop oral vaccines for mass vaccination of farmed fish species. Furthermore, using various examples from the human and veterinary vaccine development, we propose additional approaches to fish vaccine design also considering recent advances in fish mucosal immunology and novel molecular tools. Finally, we discuss the pros and cons of using the zebrafish as a pre-screening animal model to potentially speed up vaccine design and testing for aquaculture fish species.

Two isoforms of piscidin from Malabar grouper, Epinephelus malabaricus: Expression and functional characterization

Two isoforms of piscidin from Malabar grouper (Epinephelus malabaricus), EmPis-1 and EmPis-2, were cloned and studied. EmPis-1 and EmPis-2 showed the different in the 3'UTR features of mRNA and gene expression patterns. AUUUA-motif-containing ARE was found in mRNA of EmPis-1, but not in that of EmPis-2. EmPis-1 and EmPis-2 expressed not only in the potential sites of pathogen entry, but also in grouper's immune-related tissues such as head kidney (HD), peripheral blood leukocytes (PBL) and spleen. The expression level of EmPis-1 was higher than that of EmPis-2 in most fish tissues. Expression of both EmPis-1 and EmPis-2 were upregulated by V. parahaemolyticus significantly in the PBL, HD and spleen. Besides, expression of EmPis-1 was upregulated in gills. The putative mature peptides of EmPis-1 and EmPis-2, which were predicted to adopt an amphipathic α-helical conformation, posessed excellent microbicidal activities against both gram-negative and -positive bacteria. The hemolytic activity of the putative mature peptides of EmPis-1 and EmPis-2 increased in a dose-dependent manner to both grouper erythrocytes and rabbit erythrocytes. Interestingly, grouper erythrocytes were less vulnerable than rabbit erythrocytes to the peptides. Grouper piscidins excluded the signal peptide were not the inactive precursors but possessed high microbicidal activity evidenced by minimum bactericidal concentration (MBC) assay and by the scanning electron microscope (SEM) observation. The present phylogenetic analysis did not support the suggestion that piscidins are ancient AMPs widespread across invertebrate and vertebrate taxa, and that piscidins are included in the cecropin superfamily. Collectively, the present data improve our understanding of the piscidin family, and give greater insights into EmPis-1 and EmPis-2 of the grouper immune system.

Probiotics, immunostimulants, plant products and oral vaccines, and their role as feed supplements in the control of bacterial fish diseases

There is a rapidly increasing literature pointing to the success of probiotics, immunostimulants, plant products and oral vaccines in immunomodulation, namely stimulation of the innate, cellular and/or humoral immune response, and the control of bacterial fish diseases. Probiotics are regarded as live micro-organisms administered orally and leading to health benefits. However, in contrast with the use in terrestrial animals, a diverse range of micro-organisms have been evaluated in aquaculture with the mode of action often reflecting immunomodulation. Moreover, the need for living cells has been questioned. Also, key subcellular components, including lipopolysaccharides, have been attributed to the beneficial effect in fish. Here, there is a link with immunostimulants, which may also be administered orally. Furthermore, numerous plant products have been reported to have health benefits, namely protection against disease for which stimulation of some immune parameters has been reported. Oral vaccines confer protection against some diseases, although the mode of action is usually linked to humoral rather than the innate and cellular immune responses. This review explores the relationship between probiotics, immunostimulants, plant products and oral vaccines.

Oral Vaccination of Fish - Antigen Preparations, Uptake, and Immune Induction

The oral route offers the most attractive approach of immunization of fish for a number of reasons: the ease of administration of antigens, it is less stressful than parenteral delivery and in principle, it is applicable to small and large sized fish; it also provides a procedure for oral boosting during grow-out periods in cages or ponds. There are, however, not many commercial vaccines available at the moment due to lack of efficacy and challenges associated with production of large quantities of antigens. These are required to stimulate an effective immune response locally and systemically, and need to be protected against degradation before they reach the sites where immune induction occurs. The hostile stomach environment is believed to be particularly important with regard to degradation of antigens in certain species. There is also a poor understanding about the requirements for proper immune induction following oral administration on one side, and the potential for induction of tolerance on the other. To what extent primary immunization via the oral route will elicit both local and systemic responses is not understood in detail. Furthermore, to what extent parenteral delivery will protect mucosal/gut surfaces and vice-versa is also not fully understood. We review the work that has been done on the subject and discuss it in light of recent advances that include mass production of antigens, including the use of plant systems. Different encapsulation techniques that have been developed in the quest to protect antigens against digestive degradation, as well as to target them for appropriate immune induction are also highlighted.

Nanodelivery Systems as New Tools for Immunostimulant or Vaccine Administration: Targeting the Fish Immune System

Fish disease treatments have progressed significantly over the last few years and have moved from the massive use of antibiotics to the development of vaccines mainly based on inactivated bacteria. Today, the incorporation of immunostimulants and antigens into nanomaterials provide us with new tools to enhance the performance of immunostimulation. Nanoparticles are dispersions or solid particles designed with specific physical properties (size, surface charge, or loading capacity), which allow controlled delivery and therefore improved targeting and stimulation of the immune system. The use of these nanodelivery platforms in fish is in the initial steps of development. Here we review the advances in the application of nanoparticles to fish disease prevention including: the type of biomaterial, the type of immunostimulant or vaccine loaded into the nanoparticles, and how they target the fish immune system.

Protein transduction domain of transactivating transcriptional activator fused to outer membrane protein K of Vibrio parahaemolyticus to vaccinate marbled eels (Anguilla marmorata) confers protection against mortality caused by V. parahaemolyticus

Although immersion and oral vaccination are the most practical methods for fish farmers, their applications are very limited due to low immune stimulation effect. We used the protein transduction domain (PTD) of transactivating transcriptional factor (TAT) derived from HIV TAT protein to increase the delivery efficiency of aquatic protein vaccines. Vibrio parahaemolyticus outer membrane protein K (ompK), a reported vaccine candidate for the prevention of V. parahaemolyticus infection, was fused with TAT-PTD expressed in Escherichia coli. We found that PTD-ompK fusion protein effectively penetrated into marbled eel bodies. Analysis of ompK antibody titres demonstrated that immersion vaccination with PTD-ompK was superior to ompK alone and induced robust immune stimulation in marbled eels. Both active and passive protection analyses against immersive challenge with V. parahaemolyticus strains demonstrated that marbled eels immunized with PTD-ompK survived significantly longer than those immunized with ompK alone. Our results indicated that TAT-PTD could be served as is an efficient delivery system for aquatic immersion vaccinations against various infectious diseases commonly seen in aquatic farm industry.

Polymer nanotechnology based approaches in mucosal vaccine delivery: challenges and opportunities

Mucosal sites serve as the main portal for the entry of pathogens and thus immunization through mucosal routes can greatly improve the immunity. Researchers are continuously exploring the vaccination strategies to engender protective mucosal immune responses. Unearthing of mucosal adjuvants, that are safe and effective, is enhancing the magnitude and quality of the protective immune response. Use of nanotechnology based polymeric nanocarrier systems which encapsulate vaccine components for protection of sensitive payload, incorporate mucosal adjuvants to maximize the immune responses and target the mucosal immune system is a key strategy to improve the effectiveness of mucosal vaccines. These advances promise to accelerate the development and testing of new mucosal vaccines against many human diseases. This review focuses on the need for the development of nanocarrier based mucosal vaccines with emphases on the polymeric nanoparticles, their clinical status and future perspectives. This review focuses on the need and new insights for the development of nanoarchitecture governed mucosal vaccination with emphases on the various polymeric nanoparticles, their clinical status and future perspectives.

Prevention of bacterial foodborne disease using nanobiotechnology

Foodborne disease is an important source of expense, morbidity, and mortality for society. Detection and control constitute significant components of the overall management of foodborne bacterial pathogens, and this review focuses on the use of nanosized biological entities and molecules to achieve these goals. There is an emphasis on the use of organisms called bacteriophages (phages: viruses that infect bacteria), which are increasingly being used in pathogen detection and biocontrol applications. Detection of pathogens in foods by conventional techniques is time-consuming and expensive, although it can also be sensitive and accurate. Nanobiotechnology is being used to decrease detection times and cost through the development of biosensors, exploiting specific cell-recognition properties of antibodies and phage proteins. Although sensitivity per test can be excellent (eg, the detection of one cell), the very small volumes tested mean that sensitivity per sample is less compelling. An ideal detection method needs to be inexpensive, sensitive, and accurate, but no approach yet achieves all three. For nanobiotechnology to displace existing methods (culture-based, antibody-based rapid methods, or those that detect amplified nucleic acid) it will need to focus on improving sensitivity. Although manufactured nonbiological nanoparticles have been used to kill bacterial cells, nanosized organisms called phages are increasingly finding favor in food safety applications. Phages are amenable to protein and nucleic acid labeling, and can be very specific, and the typical large "burst size" resulting from phage amplification can be harnessed to produce a rapid increase in signal to facilitate detection. There are now several commercially available phages for pathogen control, and many reports in the literature demonstrate efficacy against a number of foodborne pathogens on diverse foods. As a method for control of pathogens, nanobiotechnology is therefore flourishing.